SuzukiSavage.com - Cylinder Head Porting & Flow Test

DragBikeMike

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Re: Cylinder Head Porting & Flow Test
Reply #75 - 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.

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philthymike

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Re: Cylinder Head Porting & Flow Test
Reply #76 - 07/11/19 at 18:24:34

VortecCPI wrote on 05/31/19 at 04:55:35:

philthymike wrote 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.

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...

Hi Vortec. I was just curious about that aftermarket CDI. Did it come with any kind of technical specs that you could share?
Any idea how it differs from the OEM unit?

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07 S40 (Thumpy): 666cc big bore, stage 2 webcam, dyna muffler, 412 shocks, Barnett clutch, Kawasaki ZL900 FE

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28755 L.A. California Gender:	Re: Cylinder Head Porting & Flow Test Reply #77 - 07/11/19 at 20:03:20 I'm thinking aluminum low temp welding rods. good for about 700°F
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DragBikeMike

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Re: Cylinder Head Porting & Flow Test
Reply #78 - 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.

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28755 L.A. California Gender:	Re: Cylinder Head Porting & Flow Test Reply #79 - 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
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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10596 Oklahoma Gender:	Re: Cylinder Head Porting & Flow Test Reply #80 - 07/12/19 at 03:39:07 Michael, your modification of the port is looking a lot more like the DR exhaust port. 👍
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zevenenergie Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1250 The Netherlands Den Haag	Re: Cylinder Head Porting & Flow Test Reply #81 - 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.
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DragBikeMike Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 4167 Honolulu	Re: Cylinder Head Porting & Flow Test Reply #82 - 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?
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flatout YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 10	Re: Cylinder Head Porting & Flow Test Reply #83 - 11/19/20 at 06:22:15 updates?
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DragBikeMike

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Re: Cylinder Head Porting & Flow Test
Reply #84 - 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.

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