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Message started by DragBikeMike on 04/04/19 at 00:16:53

Title: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:16:53

In late January I posted a report on a cylinder head I was testing. I refer to it as the HammerHead. It was the victim of a valve/piston collision that beat the ever lovin daylites out of the thing. I salvaged the head for testing, and then did flow comparisons between the HammerHead and a good used head. The heads flowed almost the same, so I deemed the HammerHead a valid test mule for trying various porting techniques. Since January, I have done extensive testing on the heads. Now it’s time to share some of that hard-earned information.

I will start with a correction. In January, I stated that I would be using 10” H2O as my test pressure for all the tests. I would either test at 10”, or test at the highest pressure I could achieve with my little bench, then convert the results to 10” using the DTec conversion tables. After running numerous tests, and starting modifications on the intake port, it became apparent that 10” wasn’t gonna cut it. I needed more oomph. Also, I kept seeing results that led me to believe that at some point above 10” the forces acting on the air were causing it to naturally pull away from the bottom of the port and run along the top. Apparently, that’s a well-known phenomenon and to be expected. I needed to up the ante, so I switched to a double vacuum cleaner setup. As it turns out, that still wasn’t enough juice, so I added in a third vacuum cleaner. Now I was cookin.

This is the three-vacuum setup for intake tests.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:17:51

This is the three-vacuum setup for exhaust testing.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:19:25

The three-vacuum setup allowed me to test the intake at 15” H2O all the way up to .400” lift, and it allowed me to test the exhaust at 28” H2O all the way up to .400” lift. I could get some serious test data now.

I knew all my test data on the intake would be taken at a maximum test pressure of 15” H2O; the rig didn’t have enough reserve to test the intake at higher pressures. I also knew I had 28” H2O available to test the exhaust, but also had the option to test the exhaust at 15”. I could test the exhaust at the higher pressure to evaluate changes, and then test again at 15” to compare the two ports at the same test pressure. Sweet! To provide a little reassurance, I tested the stock exhaust port at both pressures, converted the 28” data to 15”, and it came out essentially the same as the data I actually recorded at 15”. That’s gonna work.

I was able to make big improvements to both ports, but the exhaust port really responded well. The intake flow was improved by 17.5%, from a maximum 167.6 CFM to a maximum 196.9 CFM. The exhaust was improved by 43.1%, from a maximum of 114.2 CFM to a maximum of 163.4 CFM. The flow bias is now 83%. The final numbers are actual 15” flow values (no data was converted).

I took flow readings at .025” lift increments (16 readings). So, a more realistic way to look at the data is to add up the flow readings and divide by 16. That gives you an average flow for the configuration. If you use average flow to evaluate the modifications, the intake has improved about 15% (121 stock vs 139 ported), and the exhaust has improved about 34% (90 stock vs 121 ported). I believe this is a more realistic way to view the results.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:20:13

Here’s a look at the intake graph for 15” H2O test pressure.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:20:55

Here’s a look at the exhaust graph for 15” H2O test pressure.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:21:40

These flow improvements were achieved without increasing port volume. In fact, the intake port volume was decreased by 2cc, from 112 to 110, and the exhaust port volume was decreased by 1cc, from 66 to 65. I think that’s a big plus. These should not be lazy ports.

Except for flush exhaust valve guides, every modification I list results in a measurable gain in flow.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:23:09

Modifications to the intake port included:

A general clean-up of the port by removing rough cast areas, blending the valve seats into the aluminum port wall, and attempting to blend and increase the short side radius.

Back-cutting the valves 30°.

Replacing the stock 33mm valves with Kibblewhite 34mm valves. The Kibblewhite valves have undercut stems that increase the port cross section slightly and reduce weight. They are 1mm larger than stock, but are 3 grams lighter.

Raising the bottom of the intake port to increase to the short side radius.

Widening the individual port runners by .050”.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:27:41

Let’s look at the various modifications to the intake and discuss the pros & cons.

The general clean-up of the port provides about a 1.5% increase in flow. It is straight-forward and relatively low risk. Pretty much anyone with a Dremel tool and steady hand can pull it off. Be careful around those valve seats.

Back-cutting the intake valves 30° provides about 1.0% increase in flow. Gains are realized for lifts up to about .250”. If you have the tools, it’s easy to do and seems low risk. You will need a lathe or Neway Gizmatic to do it. If you don’t have the tools, a trip to your local engine rebuilder and a few bucks should get it done.

Replacing the 33mm valves with 34mm valves requires a higher level of skill and tools. The seat inserts must be enlarged by cutting the throats with 60° and 75° cutters. The valve seating surface must be re-established with a 46° cutter, and the new seat must be blended to the combustion chamber with a 31° cutter.

You will need all the various cutters, and of course the valves (about $120). The valve seats are hard as diamonds. It takes a while. You can expect about 3.5% improvement in flow. Also, the valves I have procured are for a 1972 Honda CB350. They are not an “exact” replacement. I still have a bit of work in front of me to make those valves work in the LS650.

You can order custom valves that will fit exactly, but it will cost more. I don’t know what that additional cost is. More to come as I start doing the official mods to my good head.

Another option is a junk Honda CB350 engine. If it suffered infant mortality, you might be able to score pristine valves and the associated spring retainers and cotters.

Raising the bottom of the intake port is inexpensive and highly effective. My early declining pressure tests show that the raised floor with increased radius is good for a whopping 6.6% increase. That’s with stock valves. With the 34mm Kibblewhites, the raised floor provided a phenomenal 11.6% increase in flow. Both these tests used back-cut valves.

This raised floor modification really seems to do the trick. It reduces the port volume while increasing flow substantially. Believe me, I spent many hours of testing this. It defies logic. But after testing this configuration over and over, I am convinced it works. Fill in the floor of the port, blend it in just right, Baaaammmm! Instant gratification. I did this like ten times and always got identical results. The trick is the blend into the bowl (the area just above the seat insert) on the lower side of the runner (short side). You really don’t want any filler in that area. You should be able to run your finger over the bottom of the port through the bowl area and feel a nice, generous radius, with no abrupt changes in direction.

How do you raise the bottom of the port? Epoxy. If you fish around on the web, you will see that there are folks using this technique. It’s also discussed in various performance publications. Manley and Goodson both offer epoxy putty specifically intended for intake port modification. I am currently performing some tests to determine what might be the best product and surface prep for me. I really like JB Weld products. Stay tuned for a full report.

Widening the port runners by .050” helps to compensate for the loss in cross section due to the epoxy filler on the bottom. It’s good for about a 1% improvement. It’s simple and low impact. However, when I tried opening it up another .030” I started running out of go power. I was having trouble maintaining 15” H2O. I am not sure what will happen if the runners are widened more that .050”. My flow graph reflects the .050” wider port runners. If you want to go past that, you are on your own.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:31:00

Let’s take a look at some of the intake port mods.

Here is a shot of the general cleanup on the intake.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:32:16

Let’s have a look at the 34mm Kibblewhite next to the stock 33mm valve. Kibblewhite on left.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:33:05

This is what the raised intake port looks like. Note the shape and blending of the epoxy filler.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:33:55

Here is a detailed map of the finished intake port.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:38:12

Modifications to the exhaust port included:

A general clean-up of the port by removing rough cast areas, blending the valve seats into the aluminum port wall, and attempting to blend and increase the short side radius.

Back-cutting the valves 30°.

Cutting back the valve guides until they are flush with the roof of the port.

Filling in the step in the roof of the port to provide a smoother flow path. I refer to the step as the “Dipsy-Doodle” (DD).

Enlarging the port opening (location “D”, see sketch) from 1.3” to 1.5” diameter and blending the adjacent wall to provide as straight a flow path as possible. Material removed from top and sides of port, floor of port left as-is. This is a “D” shaped port.

Note: I used a 1.5” ID test adapter to connect the test bench to the exhaust port. When I tested with adapters smaller than 1.5” ID, flow dropped dramatically.

Let’s look at the various modifications to the exhaust and discuss the pros & cons.

The general clean-up of the port provides about a 1.5% increase in flow. It is straight-forward and relatively low risk. Just like the intake, pretty much anyone with a Dremel tool and steady hand can pull it off. However, the opening is a lot smaller and there are lots of nooks & crannies that are hard to get at. Be careful around those valve seats so you don’t end up with any rat bites in the seating surface.

Back-cutting the exhaust valves 30° provides about 1.0% increase in flow, with gains mostly at lifts up to about .250”. If you have the tools, it’s easy to do and seems low risk. Like the intake valves, you will need a lathe or Neway Gizmatic to do it. If you don’t have the tools, a trip to your local engine rebuilder and a few bucks should get it done.

Cutting back the valve guides until they are flush with the port didn’t seem to improve flow very much. I found that odd. However, with various combinations the flush guides appeared to have a positive effect. Removing the guides, cutting them, and reinstalling is not an option as the interference fit is reduced dramatically when the guides are pushed out. You must install oversize guides. It is possible to grind or machine the guides in-place, but it just doesn’t seem to be worth the effort. I’m gonna leave the exhaust guides alone.

Filling in the Dipsy-Doodle improved flow by 4.5%. It worked well. It should be inexpensive and relatively low risk. In the event of a failure, flow should carry the filler material away from the valves. Fishing chunks of filler material out of the muffler shouldn’t be too hard. The trick will be coming up with a product that can live in the extreme operating environment.

A good anchor profile will have to be cut in the surfaces of the DD. That should be easy with a Dremel along with number 113 & 199 high speed cutters.

JB Weld “Extreme Heat” paste is rated to 2300°F, but it’s single-component water-based. That means it shrinks as it sets up. I currently have a test specimen filled with the product. Stay tuned for the results.

As expected, enlarging the port opening from 1.3” to 1.5” was a grand slam. It resulted in a 25.3% improvement. Except for some minor cleanup, all material was removed from the sides and top of the port. There’s not much flow across the bottom so leave it alone. You end up with a “D” shaped port.

It should be noted that this modification’s effectiveness can only be realized if a proper 1.5” or larger exhaust pipe is used. Using the stock header kills the effectiveness of this modification. More on this later in the report.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:39:25

Let’s look at some of the exhaust port mods.

Here is a shot of the general cleanup on the exhaust. Note the crack. There are two cracks in this port. They run all the way up through the guide boss into the spring seat above. It’s the sort of thing you would expect when an irresistible force meets an immovable object. Snapped the valve off too.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:40:25

Typical backcut valve. I used Honda valves for the testing so as not to risk the stock valves. Backcut Honda on left, stock valve on right.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:41:48

Here we have the filled in Dipsy-Doodle along with the 1.5” D-shaped outlet. The filler material is JB Weld “High Heat” putty just for flow testing. The putty is only rated to 450°F. It won’t hold up in the real world. I will have to find a better filler material. Hopefully the “Extreme Heat” product works out.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:42:44

Here we see the filler blend at the exhaust guide boss.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:43:27

Here is a detailed map of the finished exhaust port.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:44:24

I mentioned that the 1.3” pipe is not going to complement the enlarged port outlet. You need a 1.5” ID or larger pipe to take advantage of the enlarged port. When I tested the enlarged port with a 1.3” adapter, the flow didn’t improve much. I was compelled to switch to a larger adapter. That worked great. This is the enlarged 1.5” ID adapter I used.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:45:15

I decided that it might be a good idea to do some tests to see how the stock exhaust pipe affected flow. I started this whole project months ago with the intent of coming up with an insert to bridge the diverging/converging void between the 1.30” port outlet and the 1.27” pipe inlet. This photo should give you an idea of what I am talking about.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:46:00

The void is formed by the juncture of the diverging port bevel and the converging pipe inlet. I’m sure you are familiar with the bevel.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:46:46

And the pipe entry looks like this.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:47:34

The intent of the insert is to provides a flow path with a uniform cross section from the 1.3” port outlet to the actual 1.27” pipe inlet. I came up with an insert and my tests show some good results. When used with a stock head and a stock exhaust header pipe, the 1.3” insert increased flow by 4.2 %. I will be doing a separate post with all the details on the insert. Here is a look at what I came up with.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:48:35

I ran some tests on the heads with the stock header installed.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/04/19 at 00:54:55

When the stock header was installed on the stock head, flow was reduced by 10%.

When the stock header was installed on the ported HammerHead, flow fell by 27%.

For these comparisons, I used 28” H2O test pressure.

I don’t think it’s a good approach to run the 1.27” ID header on a souped up head. It will probably work a little better than stock, but there are other ways to get that kind of power aside from porting the head. Porting the head and slapping on the stock header pipe seems to defeat the purpose of the port work. All that port work choked off by that teeny-weeny stock header. My goodness!

I think this test came out well. The flow improvements are substantial, and I think we can all benefit from the results. I will keep you informed regarding my progress on the good head, along with the results of my epoxy and filler putty tests. Of course, the special insert post is forthcoming. I think it's a simple and cheap improvement.

As usual, I invite your comments. What is your real-world experience with porting the Savage head? Anybody out there got any concrete data (like a dyno run, or some technically reasonable performance measurement)? If you performed similar port mods, did you have to make any significant adjustments to carburetion or ignition timing? Any problems with detonation, fuel octane, etc.? How’s the reliability? How’s the clutch holding up?

Once again, I must thank Fast650 for his generous donation (the HammerHead). It has been invaluable. He also played an important role in evaluating my test data and keeping me on track. This has been a very long and difficult project, but well worth the effort.

Knowledge is power.

Best regards, Mike

Title: Re: Cylinder Head Porting & Flow Test
Post by hotrod on 04/04/19 at 06:23:58

DBM: Thank you for all your work. I can't think of attempting any of this without first getting a 1.5" header pipe. Mac has a 2". Who sells a 1.5 ? Thanks again.

Title: Re: Cylinder Head Porting & Flow Test
Post by batman on 04/04/19 at 12:21:41

Mike have you ever considered reducing the DD-2, that exists between point C & D ?

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/05/19 at 00:21:07

That is an excellent observation Batz. You know, when you get an idea and you start plowing ahead with it, you lose sight of other possibilities for improvement. I must admit that I didn't consider the second Dipsy-Doodle. I should have tested that.

Seems to me if I fill that area in, I will have to widen the port outlet to compensate for the loss in cross section. I will end up with an oval port. That's certainly an option. I have seen other oval exhaust ports that reportedly worked well.

Currently, I am set up for intake testing. I have three new carburetors that I'm evaluating. When I reconfigure for exhaust testing, I will apply some modelling clay to the second Dipsey-Doodle and see what shakes out. Maybe there's some more flow there.

Title: Re: Cylinder Head Porting & Flow Test
Post by ohiomoto on 04/05/19 at 07:50:11

I'm not arguing with your results, but could there possibly be a reason for those dipsey-dos??

Could those actually be a feature the enginers put in for some sort of scavaging or back pressure effect??

I'm thinking along the lines of "if it were all about airflow then you could argue that we shouldn't run pipes at all". I believe Suzuki's engineers are probably a pretty smart group and either put those there for a reason or were mad as hell they had to leave them there at all.

Title: Re: Cylinder Head Porting & Flow Test
Post by batman on 04/05/19 at 08:06:19

Mike ,I was thinking the loss in cross section might be the key to a bit better performance ,as it would not allow the gases to expand , and retain it's velocity all the way into the header pipe. You did a fine job with DD1 , while increasing the size adds to performance, I think the largest gain was from the gases not able to expand at that point, when volume increases , velocity decreases, and pressure (dare I call it back pressure ?) increases ,killing flow. Using filler to change the S shape to a gentle curve from the "shelf " to the header may see a further increase in performance. (not sure , but curious )

Title: Re: Cylinder Head Porting & Flow Test
Post by batman on 04/05/19 at 09:09:59

3B3C3D3B393B203B540 wrote:

Ohio, I think any back pressure effect that early in the exhaust path would have only a negative effect . Scavenging occurs when the pressure wave (moving at a speed of nearly Mach 1) returns from the end of the header pipe where it has expanded, to find the exhaust valve before it closes and the intake valve slightly open , the DD's are much to close . The stock cam (and any derived from it -stage 3) has negative overlap which means there's no chance of scavenging in any case, which keeps emissions low on a bike equipped with a carb rather than FI. The bad exhaust channel in the head keeps hp down a factor that seemed right for an entry level bike.

Title: Re: Cylinder Head Porting & Flow Test
Post by Fast 650 on 04/05/19 at 10:39:59

6661606664667D66090 wrote:

I'm thinking along the lines of "if it were all about airflow then you could argue that we shouldn't run pipes at all". I believe Suzuki's engineers are probably a pretty smart group and either put those there for a reason or were mad as hell they had to leave them there at all.

The engineers are a smart group. The problem is the intended market audience for these bikes, and that the engineers are not at the top of the decision making chain. Someone above them said "Hey, can you keep the cost of production really low so we can sell them cheap and still make a profit?" and we are stuck with their design. The valve spring location kind of mandates that last part of the dipsy with the current design. To correct the port shape would require the head to be taller so that the port could be moved enough to eliminate the dipsydoodles. And a taller head would require frame changes and other engine changes (longer cam chain, different rockers, etc) that would increase the cost. We ended up with the best that they could offer under the circumstances.

Title: Re: Cylinder Head Porting & Flow Test
Post by Armen on 04/06/19 at 06:38:49

Thanks for all your hard work and incredible documentation!
-Armen

Title: Re: Cylinder Head Porting & Flow Test
Post by batman on 04/06/19 at 16:55:28

Yes thanks again Mike ! Always informative !

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/06/19 at 22:28:10

The kudos need to go to Fast650. Filling the Dipsy-Doodle on the exhaust and raising the intake floor with epoxy were Fast650's ideas. He sent me links on the intake epoxy trick and directly suggested the DD fill. Plus, he donated the HammerHead. F-65-0 should get the credit here.

Regarding the additional work on the exhaust port, it's already around 83% flow bias. It was way easier souping up the exhaust than souping up the intake. My limited understanding is that we really want around 70 to 80% flow bias for a naturally aspirated engine. If we were running boost, then we might want more than 80%.

When I get setup for exhaust testing again, I will try to do a proper test on DD-2 using clay, just to see what happens. But I am also a bit skeptical about coming up with a filler that can hold up. The first Dipsey-Doodle is in a fairly tight notch. We have a much better chance of anchoring the filler in that notch. The second Dipsey-Doodle looks a lot more challenging in terms of anchoring the filler material..

My filler material test specimens are all cured and ready to be tortured. Let's see how that shakes out.

Regarding Suzuki engineers incorporating the DD for backpressure: the incredibly small 1.27" ID head pipe gives this system all the backpressure any engineer could ever dream of. If you fiddle around with any of the readilay available formulas for header pipe ID, you will find that this particular setup is most likely intentionally designed for a tractor-pull engine. The teeny-weeny head pipe, zero-overlap cam, undersize carburetor, single-cylinder large-displacement engine, 5+ pound flywheel, all combine for the perfect entry-level motorcycle. Light-weight, loads of low end torque, exilerating (at-first) but not very intimidating acceleration. I think they got exactly what they were looking for.

Our job is to make it intimidating. 8-)

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 04/06/19 at 22:58:02

One additional comment, I am surprised there hasn't been any discussion regarding "raising the floor of the intake with epoxy". It kind of seemed illogical to me. Reduce the cross section to increase flow? IMO, this isn't some sort of velocity trick. It seems more likely that the improved short side radius really does the trick. Also, I found that if you don't do it just right it will choke off the flow. I think that pitfall could be avoided by simply testing the port with a vacuum cleaner and manometer. Take a baseline reading before starting and then make sure your finished port pulls significantly less vacuum when you are done. Very easy to do and requires almost zero cash outlay.

Title: Re: Cylinder Head Porting & Flow Test
Post by Fast 650 on 04/07/19 at 08:14:26

26202F53515652620 wrote:

Now we just need a cam with a bit of overlap and a piston that is tall enough to correct the deck height but with enough of a dish to keep the compression ratio reasonable. :)

Title: Re: Cylinder Head Porting & Flow Test
Post by batman on 04/07/19 at 12:11:49

Fast650 thank you also!!! I really have no idea , but what about removing the dome from a DR piston, I don't know if it would retain it's strength? due to the wrist pin location the piston , it sits higher in the cylinder at TDC ,which would raise compression.( don't know how much ( 9-9.5?)
the DR cam does have 6 degrees of overlap @ .050

Title: Re: Cylinder Head Porting & Flow Test
Post by Fast 650 on 04/07/19 at 23:30:12

You are close to what I was thinking. What I meant would require a new casting to be custom made. Easiest way to visualize it would be to imagine a stock LS piston, then imagine a 1/8" thick ring about 1/2" wide that sits on top of the piston. That would remedy the deck height problem, give it a quench area, and the dish would be enough to keep the CR down enough to not be detonation prone..

As for the valve overlap, a little more overlap would allow for better scavenging from pipe tuning. The current overlap isn't enough for it to have much of an effect.

Title: Re: Cylinder Head Porting & Flow Test
Post by Iceman4193 on 05/05/19 at 17:50:12

I am wanting to open the exhaust up to a 1.5" but I am not clear on just what material you are removing? Do you use the existing header bolt on piece and just open it up a bit or is there a different way of mounting the larger header onto the head?

Title: Re: Cylinder Head Porting & Flow Test
Post by VortecCPI on 05/06/19 at 15:23:43

6661606664667D66090 wrote:

No pipe at all means 14.7 PSIA acting directly on the exhaust valve. Not good... At low engine speeds the ambient pressure would push spent exhaust gas right back into the combustion chamber. This not only dilutes the fresh incoming intake charge but also kills VE by reducing cylinder pressure. The result is a big lack of power due to crappy efficiency.

A properly-tuned exhaust system can actually create positive pressure (a sort of super-charging) and increase VE and cylinder pressure over small operating ranges. A good reverse-cone megaphone system can achieve such an effect, as can a properly-tuned intake runner. ALL modern auto and boat engines have tuned intakes today...

Good read here: http://victorylibrary.com/brit/mega-c.htm

And here: https://www.allpar.com/racing/ramchargers.html

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 05/06/19 at 23:21:37

Iceman, it's a bit unclear to me what exactly you are asking. Are you interested in how to determine where to removal material from the cylinder head exhaust port? If so, then I hope this helps.

I purchased a large nylon washer and cut the outside diameter to fit snug in the exhaust socket. Then I cut the inside diameter of the washer to 1.5". I used the washer as a template for enlarging the port opening from 1.3" to 1.5". The template serves as a guide so that your finished opening is centralized. I suggest that you not remove material from the bottom of the port. It should remain flat. You end up with an opening that is sort of like a capital "D" laying on it's side.

Here is a shot of the template.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 05/06/19 at 23:28:55

Use a scribe and trace an outline of the enlarged opening onto the head, then carefully grind and blend until you reach the scribe line, except for the bottom of the port, that should be flat. It should look like this when you are finished. Note the arced scribe line along the bottom of the port. I didn't grind along the bottom so you can still see the scribe line.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 05/06/19 at 23:30:36

Don't fire up your die grinder unless you are sure what you are trying to achieve. If in doubt, ask for more help.

Title: Re: Cylinder Head Porting & Flow Test
Post by Iceman4193 on 05/10/19 at 18:31:01

26202F53515652620 wrote:

Don't fire up your die grinder unless you are sure what you are trying to achieve. If in doubt, ask for more help.

I ah see it now. I am trying to decide between a 95 or a 96mm wiseco piston right now and I am assuming opening up the exhaust a bit to allow for better flow for larger displacement would be good. Any ideas on teh 95 vs the 96?

Title: Re: Cylinder Head Porting & Flow Test
Post by LANCER on 05/11/19 at 04:02:11

Any of the WIseco pistons works just fine. Which one depends on whether you want to bore the cylinder and the added expense of it. The 94mm just requires honing the cylinder, very easy. The benefits of adding a few cc’s to overall cylinder volume is minimal compared to the boost in CR.
They are all the same price, 94-97mm.

Title: Re: Cylinder Head Porting & Flow Test
Post by Dave on 05/11/19 at 04:08:44

363C3A323E316B6E666C5F0 wrote:

[quote author=26202F53515652620 link=1554362214/30#43 date=1557210636]

I ah see it now. I am trying to decide between a 95 or a 96mm wiseco piston right now and I am assuming opening up the exhaust a bit to allow for better flow for larger displacement would be good. Any ideas on the 95 vs the 96?

When I built my engine I chose the 95mm, as it was the smallest Wiseco piston available at the time (Lancer had not had the custom Wiseco in the stock 94mm size being built yet).

The reason I used the smallest piston - is that I seldom need to use "all" the HP that my engine can make, and the majority of my riding is done on twisty county roads between 40-60 mph....and this requires 1/4 - 1/2 throttle. I wanted an engine that was economical, reliable and ran well - I was not after maximum HP. I also wanted to be able to bore the cylinder again if needed - however I now realize that the Savage engine really doesn't have any piston/cylinder issues as long as you keep the oil level up and use a good oil - Youzguyz got 160,000 miles on his bike and was able to re-use the piston and cylinder when he had his engine overhauled.

I think the cylinder head is the big restriction in how much power the engine can produce - and on a dyno the piston size is likely to make a difference on "where" the power is produce - more than on how much power is produced. I believe there is a possibility the larger pistons will reach the airflow limits of the head at a lower rpm than the smaller pistons will. So....I would expect the 94mm piston will have the maximum torque at a bit higher rpm than the 97mm piston will. The bigger pistons will make a bit more torque than the smaller pistons....but they will likely start to run out of air a bit sooner than the smaller pistons will.

So - I believe that if you want maximum bottom end grunt, you should go with the bigger piston.....even as big as the 97mm. If you want a good running engine that makes more HP because of the higher compression ratio.......but do not use full throttle often.....go with a 94mm piston and save the cost of the cylinder boring if your cylinder is in good shape.

I am well satisfied with how my 95mm Wiseco engine runs.....it is a joy to ride. Maybe someday I will build a 97mm engine and see if I am missing anything.

So

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 05/11/19 at 10:13:09

I put the very last 666cc kit on my bike and the two most noticeable things was the increase in torque and the improvement in gas mileage due to higher CR. However I put the stage 2 cam in at the same time so I don’t know what had the most influence on the overall power spread, the big bore or the cam. But with the combo my engine makes much more torque in mid and upper range than before. Low RPM torque can nearly get the front wheel off the ground and probably would if the clutch wasn’t slipping. This clutch slipping started after the engine work and has been getting worse the past two years. None of the common remedies has helped so I’m saving up for a Barnett clutch kit. Hopefully that will be the solution.

Title: Re: Cylinder Head Porting & Flow Test
Post by badwolf on 05/11/19 at 10:23:39

philthymike, You say you say better mileage with the big kit, with the h/c piston do you run hitest? Is the better mileage enough to make up for the increase in cost for hitest?

Title: Re: Cylinder Head Porting & Flow Test
Post by badwolf on 05/11/19 at 10:26:53

Riding in the mountains a couple years ago, Dave, MMRanch, and I would all use about the same amount of gas per fill-up, but Dave always paid more for hitest.

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 05/11/19 at 13:12:58

2321322C323028212932400 wrote:

philthymike, You say you say better mileage with the big kit, with the h/c piston do you run hitest? Is the better mileage enough to make up for the increase in cost for hitest?

Yeah I’ve got to run super now but the engine runs more efficiently with higher CR and takes alot less throttle than before. Up on the interstate I used to have to keep the throttle nearly pegged to keep up with 70 mph traffic. Now it’s quite alot less throttle for the same speed. To be perfectly honest I haven’t pegged the throttle at all since the upgrade. Once I get the bike up to 85 the light weight starts freaking me out on the rutted washboard mess PA calls a highway. But I’ve hit 90 and still had a bit of throttle left.

I don’t sweat about the cost of super with such a small tank. My Ducati averages 49 mpg according to its calculator and i go much much farther on a tank of gas in the Thumper than I can on the Ducati. If I was to guess I’d say I’m in the neighborhood of 56+ mpg. That’s riding heavy handed too.

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 05/11/19 at 13:16:53

Also there’s probably a traction component at work too. I’ve got really stiff shocks on their stiffest setting along with a 140/90 Avon AV72 Cobra tire in back so I get massive traction now. More power to the pavement. Rear wheel slippage became problematic after the upgrade. The back wheel would break free in 3rd gear when I got on it. Powering out of turns turned into barely controlled power slides. It would even happen riding in a straight line.

Title: Re: Cylinder Head Porting & Flow Test
Post by LANCER on 05/12/19 at 17:02:58

My most recent check yielded milage in the low 60’s.
Good efficient performance and milage can co-exist and be fun at the same time.
Besides, REX SOUNDS GREAT when HE is howling !

Title: Re: Cylinder Head Porting & Flow Test
Post by Dave on 05/12/19 at 17:37:27

Since hopping up my engine (cam, Wiseco, porting, Mikuni) I have gotten as high as 62 mpg while riding 40-60 mph around the county roads in my home turf - but I have also gotten down as low as the high 40's if I am chasing folks around in the mountains!

I don't believe the performance cams that are used in the Savage engine are wild enough to be wasteful if you are riding conservatively - but if you decide to use the HP it does take fuel to make power.

Title: Re: Cylinder Head Porting & Flow Test
Post by ohiomoto on 05/12/19 at 19:34:50

60's?! :-? :-?

Crap, I struggle to get 50's out of my cleanly jetted mostly stock bike with my fat ass (6'3" 250 lbs) on it. :'(

Title: Re: Cylinder Head Porting & Flow Test
Post by Iceman4193 on 05/22/19 at 17:26:24

Thanks for the replies guys. So the piston size will more shift the power curve rather than add power. Most of the change will be in head work, carb and a cam.

So I am thinking I will do a 95mm Wiseco, Mikuni carb, do some light porting and polishing, and look into cam options.
Are comp cams still the main option people are going with right now?
What other options are out there that are cost effective?

Title: Re: Cylinder Head Porting & Flow Test
Post by Dave on 05/23/19 at 03:56:55

2822242C202F75707872410 wrote:

Thanks for the replies guys. So the piston size will more shift the power curve rather than add power.
I believe the piston will add power across the entire rpm range.

Are cams still the main option people are going with right now?
Cams are more often done than pistons, as the cam can be replaced with the engine in the frame......or the original cams/rockers may be worn and need to be replaced anyhow.

Title: Re: Cylinder Head Porting & Flow Test
Post by Iceman4193 on 05/25/19 at 19:10:24

003B3621303C27213A323F20530 wrote:

[quote author=2822242C202F75707872410 link=1554362214/45#55 date=1558571184]Thanks for the replies guys. So the piston size will more shift the power curve rather than add power.
I believe the piston will add power across the entire rpm range.

Are cams still the main option people are going with right now?
Cams are more often done than pistons, as the cam can be replaced with the engine in the frame......or the original cams/rockers may be worn and need to be replaced anyhow.

[/quote]

I meant comp cams as in the company who regrinds cams. I was talking with Mike and he said the cam from a DR650 is good to use too. Just the stock one I assume.

Title: Re: Cylinder Head Porting & Flow Test
Post by Dave on 05/26/19 at 03:21:51

I don't know if Comp Cams does Savage Cams.

Web Cam does - but their cam grinds for the Savage aren't much better than stock. The Stage 3 that Lancer sells is his own design, and Web Cam does not offer that grind to the retail market.

The stock DR650 cam has the oil system set up a bit different. The center hole is smaller, and there are no holes at the base of the ramp in the cam like the Savage has. DragBikeMike has been using the DR650 cam successfully without the holes - however we have also found that the holes can be drilled.

Title: Re: Cylinder Head Porting & Flow Test
Post by Iceman4193 on 05/27/19 at 09:32:00

I found the DR650 cam on bike bandit for $250. Is this the best place to pick one up? Any downsides to drilling that oil hole or is the consensus that it is ok without it?

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 05/27/19 at 12:46:56

That price sounds way too high. I bought mine for around $165 from Babbitts. Make sure you are looking at a 1995 or earlier DR650. I believe my post on the DR cam provided the OEM part number. Try and dig that post up to make sure you are buying the correct part.

Title: Re: Cylinder Head Porting & Flow Test
Post by hotrod on 05/27/19 at 14:17:20

I believe that number is 12711-12D00 $165 @ Partzilla

Title: Re: Cylinder Head Porting & Flow Test
Post by Iceman4193 on 05/28/19 at 17:04:24

Awesome, glad I asked lol

Title: Re: Cylinder Head Porting & Flow Test
Post by VortecCPI on 05/31/19 at 04:55:35

594140455D41504440424C290 wrote:

A few years ago I put a Web cam and Wiseco piston in my Honda CRF230F. The Web cam is a very mild grind with a profile for low-mid work. The stock piston was ~9:1 and the Wiseco piston is about ~10:1.

The difference is quite amazing -- More power from idle to top. The engine also has an aftermrket CDI with more lead and faster curve and that also boosted off-idle and low TQ.

I later added a full custom reverse-cone megaphone system from Frank Nye at Engines Only and that added a pretty good amount of extra power from high-mid to the top. It also has a stepped pipe which broadens the TQ curve.

These engines are like the old lazy GM L-48 350 SBC. Add a good cam, raise the CR, and give it a good timing curve and new power is very easy to find. Just a pipe and rejet alone will yield a very real power increase.

This is one of the things that make these bikes so much fun...

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 06/01/19 at 21:32:08

I sorta wish I’d done the cam before the big bore just to know what effect it had alone. I’m not an expert but I have ridden bikes with competition cams and this webcam is definitely not that. The engine on mine has the stock carb and filter so it’s probably better that I have a mild grind that doesn’t necessitate increased intake flow.
What I love most is cruising along at 60 and then overtaking someone in front of me. It’s still a surprisingly rapid surge of speed. The bike can really take off at higher RPMs. It’s not shoulder dislocating like it can get on my Ducati but for a thumper it’s very gratifying and smile inducing. Wish I had a tach, it would be interesting to watch the how fast it revs up once that main jet hits. It’s a good strong pull. One of these days I’m going to focus on my intake and maybe put in the Mikuni like others here have suggested. But the bike needs better brakes before I make it any faster.
I didn’t tune the carb so I don’t have any details to share about that except it was done really well. I do know that the main jet is bigger but the rest is a mystery to me.

I agree that this is a very fun bike. And I’ve had alot of satisfaction from modding it. Even little things make a noticeable difference. Just dropping a few pounds from removing my rusted highway bars resulted in a difference I could actually feel.

Title: Re: Cylinder Head Porting & Flow Test
Post by LANCER on 06/02/19 at 05:41:08

Philthymike, I think you might enjoy a ride on a modified Savage.

Try it, you’ll like it.

Title: Re: Cylinder Head Porting & Flow Test
Post by Ruttly on 06/02/19 at 07:42:13

Mikuni VM with a UFO and a Quad flow wing and a Intelajet for that extra shitngit !

Title: Re: Cylinder Head Porting & Flow Test
Post by LANCER on 06/02/19 at 12:27:16

0F28292931245D0 wrote:

Mikuni VM with a UFO and a Quad flow Torque wing and a Dial/Intel-a-jet for that extra shitngit !

And it does, quite handily.
Great milage to boot too.

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 06/02/19 at 13:41:20

48454A4741561613240 wrote:

Philthymike, I think you might enjoy a ride on a modified Savage.

Try it, you’ll like it.

But I do this every day 8-)

Title: Re: Cylinder Head Porting & Flow Test
Post by verslagen1 on 07/10/19 at 08:31:41

I was staring at this ugly hole the other day thinking about your "flow bridge" and wondered why do we have a 1 1/2" pipe in a 2" shell?

If we drop the pipe to the bottom of the exhaust port, filled in the difference, would that improve flow?

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 07/10/19 at 14:58:13

Regarding the 1.27" pipe in a 2" shell, only da shadow knows. Who knows what the factory had in mind? Here's my guess.

A 1.27" ID pipe is gonna have about a 1.30" OD (or somewhere around 1-5/16"). I personally think that would be ugly. You gots this GREAT BIG cylinder with this puny little pipe sticking out. Since it's a cruzer bike, it gots to have the cool factor, so along with those way cool phony chrome valve covers, the design team decides its gotta have a way cool phony BIG exhaust pipe. It wont have the tractor torque they are lookin for with a 2" pipe so they do the double wall thing. To make things sweeter, the double wall is gonna help keep that outer pipe cool and the chrome will stay shiny longer.

SO, IMO the double wall thing is intended for cosmetics. It looks really cool with the BIG pipe.

Regarding lowering the pipe. I'm not sure I understand what you have in mind. Can you do a sketch, scan it as a jpeg, and post it?

I can tell you that the MAC pipe I am currently running with my modified stock muffler is running way sweet. I'm likin it. 8-)

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 07/10/19 at 15:34:46

While you're talking headers what is the deal with those powerbomb headers for dirtbikes. The ones with the lump in the middle like a snake swallowing a rat. Is that a gimmick?

I don't get where an expansion chamber type deal makes sense if it's not a 2 stroke.

Title: Re: Cylinder Head Porting & Flow Test
Post by Dave on 07/10/19 at 19:11:50

2F3736332B37263236343A5F0 wrote:

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 07/10/19 at 19:38:25

152E2334252932342F272A35460 wrote:

[quote author=2F3736332B37263236343A5F0 link=1554362214/60#71 date=1562798086]While you're talking headers what is the deal with those powerbomb headers for dirtbikes. The ones with the lump in the middle like a snake swallowing a rat. Is that a gimmick?

I don't get where an expansion chamber type deal makes sense if it's not a 2 stroke.

I am not sure exactly what is in that lump.......it has always "wondered me"?

I also don't know how those pipe work that are parallel and connected to the header pipe by a short stub pipe.....I suppose it does some kind of damping of pressure pulses.
[/quote]
Regarding the parallel pipes, could it be some sort acoustic thing? Like using phase shifting to boost or attenuate harmonic bands? Makes me think of an eqhalizer or tone control. Basically parallel tuned circuits which when recombined can cause phase cancellations.

Title: Re: Cylinder Head Porting & Flow Test
Post by verslagen1 on 07/10/19 at 20:39:03

5D5B54282A2D29190 wrote:

Regarding lowering the pipe. I'm not sure I understand what you have in mind. Can you do a sketch, scan it as a jpeg, and post it?

Top is the stock pipe with the ego shell.
Bottom is the modified pipe. Still shows the ego shell, but the pipe is lowered and you fill and trim the port to match.
http://www.savageriders.com/verslagen/images/Headermusing.jpg

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 07/11/19 at 16:14:21

I think it looks difficult to do if you use a double wall pipe. If you use a single wall pipe I believe it would be much easier.

It seems to violate one of the cardinal rules of porting, "improve the short-side radius". That being said, I personally believe that rule is more applicable to the intake, where there is only about 15 psi differential across the port. That small differential along with inertia is all you've got going for you on the intake. On the exhaust, there's upwards of 100 psi across the port, and that rising piston ain't gonna take "no" for an answer. The spent gas is goin out one way or another. So I'm not so sure the short side radius is a big deal on the exhaust.

Looks to me what you are trying to do is get rid of the dipsy-doodle while at the same time increasing or maintaining the cross section. Do I have that right?

How are you planning to fill in the dipsy-doodle? I have not yet found a suitable filler. I tested a JB Weld product but I have no confidence in it for this particular application.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1557210973

I was able to realize significant improvement in exhaust flow simply by doing the D-shaped port, enlarging the outlet to 1.5", and blending the new outlet into the runner.

I also was able to get a pretty good improvement by filling in the first dipsy with epoxy. But epoxy isn't going to hold up. I used it just to test the concept. The first dipsy lends itself more readily to anchoring a filler material. It has a tighter notch than the doodle.

At the suggestion of Batman, I tried filling in the 2nd doodle with clay and testing it. I couldn't get the clay to hold. The air flow would just pull it out and jam everything up. While the clay held tight in the first dipsy during my initial tests, I couldn't get it to hold in the 2nd doodle. I believe that the contour is more gradual and allows the clay to pull loose.

I guess I could bust out the HammerHead and set the bench up. Fill in the HammerHead 2nd doodle with epoxy instead of clay. Then see what sort of improvement I get. But the improvement I got from simply working the port as described in this post was more than satisfying, and it was real easy to do.

I'm in the middle of trying to set up a system to measure performance, so my plate is full right now. My dyno source is having problems. They installed new software and the rig isn't working right (at least not for me). I had a go at it a few weeks ago and it showed my beast making 71 ft-lbs at 2190. Somehow that doesn't instill confidence in the accuracy of the contraption. I guess it's conceivable if I was runnin a 50 shot of squeeze, but my little Savage is all naturally aspirated.

The next time I bust out the flow bench and put a head on it, I will try to test the 2nd doodle again, but I will use epoxy as a filler. I will then post what I find out.

If you have a suitable way to fill in the DD, share it with us.

Title: Re: Cylinder Head Porting & Flow Test
Post by philthymike on 07/11/19 at 18:24:34

122B3630212707140D440 wrote:

[quote author=594140455D41504440424C290 link=1554362214/45#47 date=1557594789]I put the very last 666cc kit on my bike and the two most noticeable things was the increase in torque and the improvement in gas mileage due to higher CR. However I put the stage 2 cam in at the same time so I don’t know what had the most influence on the overall power spread, the big bore or the cam. But with the combo my engine makes much more torque in mid and upper range than before. Low RPM torque can nearly get the front wheel off the ground and probably would if the clutch wasn’t slipping. This clutch slipping started after the engine work and has been getting worse the past two years. None of the common remedies has helped so I’m saving up for a Barnett clutch kit. Hopefully that will be the solution.

Title: Re: Cylinder Head Porting & Flow Test
Post by verslagen1 on 07/11/19 at 20:03:20

I'm thinking aluminum low temp welding rods.
good for about 700°F

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 07/11/19 at 21:55:24

Like "Alumaloy"? Very interesting indeed.

Have you used the stuff before? Have you been practicing with the rods? Do you have some sort of process in mind?

The head has quite a bit of mass. You might consider pre-heating it in an oven.

I am very much interested in anything you learn about the rods. I imagine it will take a good deal of practice and skill. Please keep us posted.

Title: Re: Cylinder Head Porting & Flow Test
Post by verslagen1 on 07/11/19 at 22:31:03

Nope, haven't used it. But it's worth a try. Might put a patch in the dipsy doodle and see if it survives.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1554878768

https://www.alumiweld.com/h2uaw.html

Title: Re: Cylinder Head Porting & Flow Test
Post by LANCER on 07/12/19 at 03:39:07

Michael, your modification of the port is looking a lot more like the DR exhaust port. [ch128077]

Title: Re: Cylinder Head Porting & Flow Test
Post by zevenenergie on 08/31/19 at 11:17:08

I used Durafix a lot, to solder aluminum. My experience is that it adheres less well to cast aluminum than to rolled aluminium types.
If you want to use it on old cast aluminum, you have to remove at least 1 mm from the surface, to get rid of dirt and grease.

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 08/31/19 at 13:34:20

Zevenenergie, what is the largest workpiece you used the Durafix on? Did you have to preheat the piece?

Title: Re: Cylinder Head Porting & Flow Test
Post by flatout on 11/19/20 at 06:22:15

updates?

Title: Re: Cylinder Head Porting & Flow Test
Post by DragBikeMike on 11/19/20 at 13:24:14

"updates?"

The Stage II head has been running great. I am currently running the original Stage II on my 94mm engine. The epoxy is holding up well, even survived a piston meltdown. I probably have logged about 5 or 6 thousand miles on the modified head.

Since my last post on this thread, I installed a Web 340b cam. That required some mods to the guides, a set of valve springs & retainers, and DR650 valves. The gory details are here.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1576548823

Then I did a Stage III head for a 97mm engine. That head had a 1.79" exhaust port and 34mm intake valves. Both intake and exhaust flowed significantly more than the Stage II. The 97mm engine is sitting on my workbench waiting to be installed and tested to see if I solved an oil leak problem. The gory details are here.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1595224521/0

Repeated flow tests confirm that altering the floor of the intake port with epoxy, if done correctly, does a good job of amping up the flow. And opening up the exhaust port all the way to 1.79" had no adverse effects. Of course there is no point in opening the exhaust larger than the header pipe you intend to use.