Engine has a mind of it's own.

[jdm9123]

Hey fellas. I have had my bike up and running now for about 2 weeks now and have put 200 miles on her since she sat for a while. I am having just a few issues that I want to have a second opinion on. The bike starts up very well after installing the pamco high output ignition. I am getting a backfire on the left cylinder on decel but only when i ease it back. If I close the throttle completely she usually wont backfire. Seems to me that if i hold the throttle at a certain position she will backfire...possibly a jet issue?(mind you I have adjusted the air/fuel screws) Second whenever i use the choke it sets the idle at about 4K which is a bit much. Is there a way to adjust the choke so it idles a bit lower? Third, the engine burns oil but only at certain times. Obviously this could be a piston ring issue but I also feel as if oil is seeping its way down to the combustion chamber from the valves after I let it sit. It's very weird that she only burns oil at random times and then other times she doesn't at all. Lastly is the exhaust leaks. I have replaced both exhaust gaskets and she still leaks at the heads. Is there a possibility the pipes are just wrong for the bike and they are not seating properly? It's driving me crazy.

One other weird thing. On the right carb the air/fuel screw is working properly to there if i screw it all the way in the engine will shut off and when I screw it out she richens up but the left carb screw wont change a thing when i screw it all the way in and back out. I have cleaned the passageway as well. Thanks fellas.

 

[retiredgentleman]

If the carb butterflys have been removed at some time and re-installed, its possible that the butterflys are not centered correctly in the carb bores. Both butterflys must be able to close 100 %. If one or both of the butterflys is not centered, then it is unable to close fully.

On the bench,the butterfly screws should be left loose, while the throttle is allowed to close under spring tension a few times. This centers the butterflys. Then tighten the screws (with blue locktite). Use a strip of paper as a feeler gauge, and adjust the sync screw for equal drag under each butterfly. That's a rough sync check but is very close.
Once installed on bike, run engine and use a manometer to do a final sync.

Use the "Dead Cylinder" method to adjust the mixture screws.

Have you read the "Carb Guide" in the Tech section?

 

[grizld1]

Nonresponse to the fuel screw is usually an indication of float system defect--leaking float, leaking valve (needle and seat), or incorrect float level. The oil burning may be due to an internal head gasket seep.

 

[jdm9123]

@ retired gentleman - I have synced the carbs once before and I believe they are both out of sorts again because the idle is choppy again. Is this a symptom of the problem you are referring to with the butterfly valves? Is the dead cylinder method in the carb guide?

@grizld1 - I have never heard of a head gasket seap before but i have noticed that the head gasket is wet from oil. Not much but maybe this is due to what you're referring to?

 

[jayel]

Hey fellas. I have had my bike up and running now for about 2 weeks now and have put 200 miles on her since she sat for a while. I am having just a few issues that I want to have a second opinion on. The bike starts up very well after installing the pamco high output ignition. I am getting a backfire on the left cylinder on decel but only when i ease it back. If I close the throttle completely she usually wont backfire. Seems to me that if i hold the throttle at a certain position she will backfire...possibly a jet issue?(mind you I have adjusted the air/fuel screws) Second whenever i use the choke it sets the idle at about 4K which is a bit much. Is there a way to adjust the choke so it idles a bit lower? Third, the engine burns oil but only at certain times. Obviously this could be a piston ring issue but I also feel as if oil is seeping its way down to the combustion chamber from the valves after I let it sit. It's very weird that she only burns oil at random times and then other times she doesn't at all. Lastly is the exhaust leaks. I have replaced both exhaust gaskets and she still leaks at the heads. Is there a possibility the pipes are just wrong for the bike and they are not seating properly? It's driving me crazy.

One other weird thing. On the right carb the air/fuel screw is working properly to there if i screw it all the way in the engine will shut off and when I screw it out she richens up but the left carb screw wont change a thing when i screw it all the way in and back out. I have cleaned the passageway as well. Thanks fellas.

the double wall stock pipes can crack internally and will puff out the condensation holes, if single wall after market pipes maybe partial old exhaust gaskets, pipes not seating correctly, check diameter of exhaust gasket and diameter of exhaust pipe

 

[retiredgentleman]

Yes, the "Dead Cylinder" method is in the Carb Guide.

Have you done a compression test?

Do you have the correct jets in the carbs?

You need to read all the information you can find about how these carbs operate. Have you read the Carb Guide fully?

Is the timing set correctly using a timing light, and does the advance unit advance the timing?

 

[jdm9123]

@retired gentleman - yes, I have a timing light and have set it to spec. I have done a compression test and I have 110psi on the right and 115psi on the left. Explain the the advanced unit timing as I am unfamiliar.

 

[retiredgentleman]

@retired gentleman - yes, I have a timing light and have set it to spec. I have done a compression test and I have 110psi on the right and 115psi on the left. Explain the the advanced unit timing as I am unfamiliar.

When you rev the engine up to 3500 rpm, do you see the timing advance to the fully advanced mark and then fall back as the engine comes back to idle?

 

[jdm9123]

so, I just checked the advance on the bike and it did advance properly at 3500. But as I have said before the left cylinder backfires terribly around 3-4k. When i put my inductive pickup on the left spark plug wire at idle it flashed correctly but as i reved it the flashes went haywire and inconsistent. I proceeded then to put the pickup on the other spark plug wire and the flashes were consistent all the way thru the rev(the right side does not backfire). Did I just find a symptom for my backfiring?