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Message started by Old Guy on 05/23/17 at 12:51:49

Title: Exhaust pipe and tuning
Post by Old Guy on 05/23/17 at 12:51:49

Hi all,

I have a Ryca high pipe on my Street Tracker. The length of the pipe is 45 inches from the head to the end of the pipe. It has a Supertrapp on the end which is another 8 inches long. Running 12 discs. The diameter of the pipe is 1 3/4 inches.

As you can guess, the bike runs like crap. It starts right up but just doesn't rev up at all. The idle air/fuel adjustment is completely ineffective. Compression is good at 135 psi, ignition timing must be right (since it is not adjustable), valves adjusted correctly. Cam chain tensioner is well within extension specs. In other words it needs some fuel/air tuning. Spark plug is black.

Any suggestions where to start?

Thanks,

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by batman on 05/23/17 at 14:45:04

Ryca has never been known to show much common sense in the design of exhaust systems for there kits,the exception being the café which uses the stock header pipe.It has to due with wave tuning ,without getting into that subject to deeply ,I'll just say, If you have the stock header and you have room to put the supertrapp,muffler on the end ,it would go a long ways toward getting your bike to run normally.You would still have to do some carb tuning .Header length for our 650 should fall between 30 to 34 inches stock header is 32 ,yours is 45 and being larger 1 3/4 inch in dia. makes it even worse,the header on the bobber (Ryca) is to short and also poorly designed.

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/23/17 at 16:10:56

This is a one piece pipe, goes up the side. Nice chrome, looked pretty good before I started the bike. Now the front half is dark...

Their (Ryca's) solution for the air intake system seems suspect, also. A right angle radiator hose topped off with a small cone filter to avoid the stock battery mounted right behind the engine. If you look at the Ryca website at the Tracker and Scrambler photos you will see what I'm talking about.

I have a large K & N filter connected directly to the carb, lots of airflow, low restriction. I changed to a small battery and moved it down so there is lots of room for the filter. The big filter makes mine look more like a flat track bike; the Ryca setup is rather foo foo.

Given that I am NOT going to change the pipe or intake or tear the motor apart for cam or piston replacement, is this a tunable combination?

I have a Mikuni VM36 on order as I understand how to tune those puppies. Lancer sent me some jets for the stock carb but this is way out of any stock headpipe/intake range.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by batman on 05/23/17 at 17:32:25

It is hard to judge if your running to lean or to rich as both will blue the pipe, the best way to check is to pull the sparkplug ,if the plug is covered with soot your very rich ,if it's bright white your lean. but the best way is to use a new plug ,run the bike at moderate high speed ,shut it of and then check the plug.I would guess due to the filter,intake, and the larger header pipe that you are running lean. Have you changed to larger jets or is your carb stock? I'm guessing your idle jet is ok(maybe) ,but when you open the throttle your going very lean .you have the jet set from Lancer you need to use it,you might need to use a main jet in the 150 to 155 range and the spacer mod would also help.

Title: Re: Exhaust pipe and tuning
Post by Ruttly on 05/23/17 at 22:03:34

John , Where in California are you located ? I have only seen pics of 2 other RYCA Trackers and they both looked like crap. Somewhere down the road they will be rare , I didn't say valuable I said rare. When I got mine Ryan told me it was the seventeenth tracker kit , that was 3 1/2 years ago and I'm getting near to finishing it. But I have been riding/tuning it since April 2016 , what a fun bike to ride , turns heads where ever I go !

Title: Re: Exhaust pipe and tuning
Post by ohiomoto on 05/24/17 at 03:09:07

You are probably way lean, but just to be clear, did the bike run properly before the conversion? And are you using the stock petcock?

Title: Re: Exhaust pipe and tuning
Post by Dave on 05/24/17 at 04:48:45

Chrome will blue even if the bike is running well - but the pipe will blue (or turn yellow/blue/purple/black) faster if the mixture is not correct. Harley uses a chrome shield to hide the hot pipes, and the Savage has an inner pipe to help keep the outer pipe cooler in hopes they blue will not occur.

Letting the bike idle excessively, riding in stop and go traffic, and local humidity can also affect how fast the pipe blues.

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/24/17 at 17:08:49

No, I did not run the bike when I got it, except to start it up and verify that it ran. I did the cosmetic work, checked the inside of the motor for cam chain problems, etc. but did no mods to the motor. I have a Raptor petcock.

I am in the San Fernando Valley. I made mine to look like a converted dirt track machine. At the Nostalgia Drag Races last weekend many thought it WAS a race bike. Asked if I had raced it. I think the alloy rims, Universal tires, exposed filters and Supertrapp helped with the image.

I just couldn't get past the Ryca gas tank with the hole in the middle, or the fact that it had rear sets. Proper dirt bikes have the foot pegs under the motor, not behind it.

I see the reasoning behind their offerings and it might be a successful marketing venture. I think mine is truer to the street tracker concept. The obviously home made metal brackets also make it look like a non factory creation.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by justin_o_guy2 on 05/24/17 at 19:44:45

What's that thing weigh?

Title: Re: Exhaust pipe and tuning
Post by Ruttly on 05/24/17 at 19:56:16

John , Very nice , that looks good ! What tank did you use ? How much fuel does it carry ? Sorry for all the questions , but I'm a street tracker nut , ok just a nut !

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/24/17 at 20:51:50

Hi again,

The thing weighs very little; I think 300-350 pounds. There ain’t nuttin’ on it that it don.tt need to run. No mirrors, speedo, fenders, etc. I do have headlight, taillight, working brake light, current registration and insurance.

Tank is from an old GS450, extensively modified. We cut it open in the front and welded in a new deepened tunnel, relocated petcock mounting, lots and lots of filling and sanding. No idea how much gas it holds; I’ve only ridden it around the block.

Once I get it running halfway decent I want to trade it or sell it. I tend to lose interest in a project when it is finished. I have an idea for my next big adventure.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by ohiomoto on 05/25/17 at 06:32:53

I thought you posted bike up before?? Did you change user names?

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/25/17 at 22:41:07

Hi again,

For some reason while I was away from the forum my user name got dropped and I haven't been able to get back. Therefore I had to use a completely new email address and start from scratch. 'Puters aren't my strong point.

I have all the parts now to attempt the tune with the Mikuni VM36. A selection of jets, needles, etc. What I want to use is an air fuel mixture meter and be scientific about it.

I had an Innovate air fuel meter kit laying around, never used. It consists of the meter, a wideband ox sensor and a bung to weld on to the exhaust. The cable supplied is 8 feet long. You are supposed to connect it to the car battery through a switched voltage. I made up my own standalone system by putting the meter in a box with a battery and a switch. I used a 2200mah 3S Lipo from my electric model airplanes. It puts out about 11 volts under load. The cable runs through a grommet on the side of the box to the ox sensor. There is no connection to the car except of course the ox sensor. No worries about grounding, ignition interference, etc. I also have an Innovate exhaust clamp that fits in the tailpipe.

First I calibrated the gauge. It read 22.x in free air, which is correct. I tried the system out on my late model vehicle. The readings were what chemists would call stoichiometric, an ideal 14.7 or close to it. It did not seem to matter if it was idling, steady state or accelerating, nothing much changed. It did go lean when coming down from high speed, which one would expect as the injectors go to a minimal duty cycle when you let off the gas. Then the "duh" Homer Simpson light came on. This was AFTER the catalytic convertor. The truck just passed smog this week so I would expect it to run clean.

Also tested it on my old pre smog car. It worked OK.

Now to put all the bike parts together and see what we find out.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by Dave on 05/26/17 at 04:50:41

John:

I used an oxygen sensor to jet my carb (both the stock carb and the Mikuni), and there was another member named Halvor that did the same thing. I had an older narrow band oxygen sensor that has a single wire to the oxygen sensor. These narrow band sensors are from computers trying to reach that magic 14.7 - and they have a very limited reading range above and below that mark....still it proved to be very useful and taught me a lot.

The reading will jump around a lot as you ride, and only at a steady throttle setting will the display be stable. When you begin to open the throttle the vacuum in the venturi will drop, and it takes a short period of time for the engine and airflow to react - but for that short period of time the mixture will go lean (the lower vacuum in the venturi pulls less fuel though the jets). If you "whack" open the throttle the vacuum drops and the lean condition is worse.....and this is why they put accelerator pumps on carbs to provide more fuel when the throttle is opened quickly. There is no way to jet to eliminate the temporary lean condition on the Mikuni Round slide carb.....the stock CV carb tries to correct for this by having the slide vacuum controlled and never letting the vacuum drop too low. (The Dial A Jet device is supposed to be able to adjust for this lean condition and add more fuel flow when it senses a lean condition).

A lean condition also is created when you let off the throttle and are slowing down or coasting. The higher vacuum pulls a lot of air through the carb - but the slide needle is dropping and will reduce the amount of fuel flow through the jet. This situation is what causes the engine to pop and backfire if you close the throttle completely when slowing down....there just isn't enough fuel flow to provide a mixture that can be ignited in the cylinder by the spark plug.

In both of the above lean conditions that occur during sudden throttle opening or sudden closing - the secret is to roll the throttle ON/OFF more slowly and never throw the engine into an excessively lean condition.

But back to the jetting - the oxygen sensor does a very good job of showing the steady state conditions at all throttle settings, and it is a very useful tool. I jetted my bike so it was just a bit richer than "stoich" The 14.7 is the best ratio for economy, and around 12.5 for power.....I am somewhere between those numbers.

When you weld in your oxygen sensor bung - I believe you should be up in the flat area between the curve at the head and the curve down by your footpegs. Most factories put the oxygen sensor in the exhaust pipe very close to the outlet of the exhaust manifold - and some systems have a second sensor located after the catalytic converter.

I have a pipe with the sensor bung already welded in - you are welcome to use it if you pay shipping both ways (but you are on the opposite side of the country from me, and it likely is easier for you to get your own pipe made). I had to drill a large hole in the outside pipe and a smaller hole on the inside pipe - and the bung is only welded onto the outside pipe.

Title: Re: Exhaust pipe and tuning
Post by VortecCPI on 05/26/17 at 05:54:25

If the idle mixture screw has no impact you may have way too much throttle position and be pulling off the main. If you bottom it out and the bike still idles it is obviously getting plenty of fuel elsewhere. A leaking cutoff/enrichener circuit might also cause such an issue.

Title: Re: Exhaust pipe and tuning
Post by Dave on 05/26/17 at 06:14:22

5E677A7C6D6B4B5841080 wrote:

The pilot circuit has 2 outlets into the carb throat....one is a bypass that allows fuel to flow before the mixture screw, and the other one passes through the adjustment screw. So the screw doesn't control all the fuel at idle.....it controls how much is being added - so a Pilot Jet that is too big can allow enough fuel to flow with the mixture screw being turned all the way in. (If the idle speed is set too high when making the adjustment, it is also possible the fuel is coming from the jet needle and adjustment of the pilot screw will have no noticeable effect).

http://i66.tinypic.com/14tsdpk.jpg

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/29/17 at 20:43:33

That’s a neat diagram and description for the stock carb. I think I will stick to the old round slide carbs as I understand them better.

It’s done! I made up a throttle cable, mounted the carb and started it up. As expected the “stock” jetting from the VM36 was not correct. However the throttle response was much better than with the stock carb. Changed the needle, needle jet, main jet and pilot jet and it started to come in. Did a Goldilocks switchout of pilot jets (too lean, too rich, just right) and we’re set. These round slide carbs are so easy to tune….

Quick trip around the block shows good response at all throttle settings. I was able to get it up to speed and it was still pulling hard in 4th gear till the wind got under my visor and started to pull my open faced dirt bike helmet off.

Will try again tomorrow with a full coverage helmet and get some plug readings. I don’t think the ox sensor will be needed, especially as I would have to remove the muffler to fit the exhaust clamp.

Total cost for the carb conversion including K & N filter, carb adapter, DIY throttle cable, lots of jets, new VM36 carb was about $220. I would suggest anybody wanting to do the carb conversion to get the whole setup from Lancer. He has a turnkey solution. I had to do a lot of fabrication on the throttle cable and lucked out on the carb jets. If you aren’t adept at shade tree mechanics, soldering, etc., and don’t have lots of experience with carb tuning it could be a frustrating experience.

I don’t mind spending the time and effort but then I’m retired and have lots of patience with mechanical things. People, not so much.

Quitting while I am ahead. Now I am ready to sell the bike and start on a new project. I’m too old to go out and play in Southern California traffic on a motorcycle. Anybody want a Tracker Savage? Current registration and insurance.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by Ruttly on 05/29/17 at 21:15:12

Old Guy, Index your throttle housing to 0 , 1/4 , 1/2 , 3/4 , WOT then go ride it start down at idle and watch your throttle while riding , make mental notes of where it's lacking and what it's doing. Your in LA area sea level ? Let me find my note book and I will get you some jetting specs or get a hold of Lancer he's the wizard either way we will get you real close and you can dial it in.

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/30/17 at 10:10:14

Hi All,

Had to order another K & N filter. The RU-1710 fit the stock carb but is too small for the VM36. I will continue with tuning with new filter.. Don't know how much itr will affect carb jetting. I'm close to sea level in the SF Valley.

Might have to find a "less urban" area to do the jetting. Too much traffic here for much steady state running and tuning, unless I do it at night.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by Ruttly on 05/30/17 at 20:04:05

Slide 2.5
Needle clip on middle grove
Pilot 20
Main 190

Mine as it was delivered from Lancer
Spot On just set mixture & idle

Title: Re: Exhaust pipe and tuning
Post by Old Guy on 05/31/17 at 23:20:40

Ruttly,

Those numbers sound about right to me, same as what I came up with on the PJ, slide and needle clip. Haven’t set the main jet yet. Waiting for the new filter to come in the mail.

I took the top off the stock carb and found some blue RTV repair of the diaphragm. I think I did that way back when I first got the bike. It seemed to be OK but I dunno. I feel a lot better now about going to the VM36 and not wasting time with the stock carb.

I tried the air fuel meter today with the sensor stuck up the tailpipe. Too loud even at idle for me. It did not work, just read 22.4. I think there is just not enough consistent gas flow to get a good reading with the tailpipe mounted clamp. Of course, an ox sensor closer to the exhaust port would be better but I'm not going to weld a bung on my expensive pipe. A “test pipe” would not have the same back pressure as the one I have so readings would be relatively useless, except for a ballpark setup. I think I’m pretty close as it is.

Will have to settle for plug reading with a throttle chop. I did some rewiring so that I can kill the motor with the right hand while pulling the clutch with the left. Let you know what I find.

John in Kalifornia

Title: Re: Exhaust pipe and tuning
Post by Ruttly on 06/01/17 at 10:15:27

I'm at 86 ft elevation so those specs should be good depending on your exhaust. But definitely in the ball park range. Let us know your final specs !