Stumped, Need Help...Sportster Running Rough!

[vcataldo]

I'm running a complete HD stock ignition and coil set up with stock ignition factory curve.
Petcock doesn't have a leak, I pulled the vacuum line and there is no gas in the line. Crank sensor has been changed, coil has been changed. The bike doesn't have VOES it has ECM and it was changed also. I live in South Florida, no icing on the carb - even though we've had some exceptionally cooler weather, it is now back up to high 70's and it's still doing the same thing. Air filter has been cleaned, then changed for a new one. Runs on both cylinders.

 

[karlsbike]

To me it sounds like you've done most logical checks and I am starting to understand your frustration.

My vote now goes to an electrical fault; is it running rich&rough continuously after some minutes of running, or is it intermittent?

Since you have replaced the coil, it leaves the ignition itself/plug wires/plugs
Where is the ignition unit located (there was earlier issues with nose cone mounted ignitions malfunctioning when heated...)

This is getting out of my league, but Hoople might have some (more) ideas?

 

[Hoople]

At this point I would port my own calibrated vacuum leak (below the butter fly or slide) into the intake manifold in order to be able to inject a little bit of air when the idle is rough. When you inject air below the throttle plate, if it is a mixture problem (very high %CO), the idle will smooth out and rise a bit. It it is something other than A/F ratio such as mechanical or an electrical issue, the idle will get worse and maybe even stall the engine.

Therefore, if it is a mixture/carb issue (just too much fuel), the vacuum leak will give rise to the RPM and clear up the roughness. If it is ignition, electrical or some other mechanical issue, the engine will run worse when you inject a small amount of air.

I know you said you don't have VOE's on your bike but if the carb has a blocked off voes port, that would be a perfect place to position your calibrated vacuum leak. You can get a Fish tank manifold valve at an Aquarium shop to dial in your vacuum leak. They work great to adjust or bleed in a small amount of air and they are dirt cheap. The key is not to dump too much air in at one time or else you will/can get misleading results.

I know you said you replaced the carb but I am still not convinced. See if you can inject a small amount of calibrated air and get a rise in RPM and smoothness. Then lower the RPM by the mechanical carb stop and see if you can get a smooth curb idle speed. If you can, then you know what the problem is. If you can not, at least you can move on to the next test.

 

[Bodeen]

At this point I would port my own calibrated vacuum leak (below the butter fly or slide) into the intake manifold in order to be able to inject a little bit of air when the idle is rough. When you inject air below the throttle plate, if it is a mixture problem (very high %CO), the idle will smooth out and rise a bit. It it is something other than A/F ratio such as mechanical or an electrical issue, the idle will get worse and maybe even stall the engine.

Therefore, if it is a mixture/carb issue (just too much fuel), the vacuum leak will give rise to the RPM and clear up the roughness. If it is ignition, electrical or some other mechanical issue, the engine will run worse when you inject a small amount of air.

I know you said you don't have VOE's on your bike but if the carb has a blocked off voes port, that would be a perfect place to position your calibrated vacuum leak. You can get a Fish tank manifold valve at an Aquarium shop to dial in your vacuum leak. They work great to adjust or bleed in a small amount of air and they are dirt cheap. The key is not to dump too much air in at one time or else you will/can get misleading results.

I know you said you replaced the carb but I am still not convinced. See if you can inject a small amount of calibrated air and get a rise in RPM and smoothness. Then lower the RPM by the mechanical carb stop and see if you can get a smooth curb idle speed. If you can, then you know what the problem is. If you can not, at least you can move on to the next test.

Brilliant idea Hoop!

Bodeen

 

[BUBBIE]

Even though you used a replacement carb. Did you USE the same choke/enricher????

Could it be the enricher sticking OPEN causing Gas to be TOO plentyful???:newsmile063:

signed....BUBBIE

 

[BUBBIE]

Anybody ask about the air-filter ?, If the same used or is it off and running RICH with out it?

signed....BUBBIE

 

[fin_676]

Anybody ask about the air-filter ?, If the same used or is it off and running RICH with out it?

signed....BUBBIE

Post number 21 says air filter cleaned then replaced
working on running rich must be either too much fuel or not enough air and the carb and air filter both being replaced
try no air filter or cover

Brian

 

[Dr.Evil]

If I remember my old hand pump vacuum tester, it had a gauge and a bleed screw. This would allow you to read and adjust the vacuum leak.

 

[vcataldo]

FINALLY...took your advice Hoople (thank you very much) and went to my local aquarium shop and got a fish tank manifold valve and started adjusting the air...found the leak and got the idle smoothed out, opened up the throttle and it was real responsive with no sputtering and NO more fouling plugs because its running rich...

Sometimes I wanna pull my hair out with these sportster!

Thanks everyone for your suggestions and input...very much appreciated!

 

[2000classic]

FINALLY...took your advice Hoople (thank you very much) and went to my local aquarium shop and got a fish tank manifold valve and started adjusting the air...found the leak and got the idle smoothed out, opened up the throttle and it was real responsive with no sputtering and NO more fouling plugs because its running rich...

Sometimes I wanna pull my hair out with these sportster!

Thanks everyone for your suggestions and input...very much appreciated!

Where was the leak?