Verifying Possible Problem

I would like to veryify my thinking. I finished doing some work on my bike which included cleaning the carbs, bench setting the carbs, setting the floats, clunk test, and changing the oil. They bike ran great. Over about two to three weeks this is what happened.

1) Popping came back. Mostly goes away when adding some choke.
2) Really rough at idle.
3) Requires more choke to start.

The cycle has brand new manifolds. No Leaks. These are the causes that I think about.

1) Needs new float needles.
2) Needs mixture adjusted. Tops are stripped therefore, need new screws.
3) Maybe new plugs.
4) Low compression

Any other ideas or thoughts?

 

By the way .. the bike runs awesome above 3000 rpm except for minor popping when letting off on gas. Once again. A little choke gets rid of that.

 

Fit new pilot mixture screws, take note how far they are out now, then you need to be slightly richer, by tiny increments, you are not far off.

 

Any idea why it would take a couple of weeks to show?

 

It's called fine tuning.

 

One more question. Until I buy new ones does it hurt to ride with just a little choke?

 

i would take another look at those pilot jets to ensure they are completely clear, maybe some gunk broke loose and plugged a couple of them up. also check for potential vacuum leaks (intake manifolds, diaphragms, throttle seals, etc.)

cheers,

Trev

 

From the symptoms and how you are using the choke, sounds like your bike is running too lean of a fuel mixture.

One reason it took a while to show could be that blockage has accumulated some more in the carbs making it even more lean.

The choke simply adds more fuel to the mix. Running with choke on makes up for the lean condition. Full choke should make it too rich. A little choke will compensate for being too lean. Running with choke on will not harm anything. But too rich will increase fuel consumption, possibly foul plugs, possibly contaminate the oil with fuel.

You wrote:
‘2) Needs mixture adjusted. Tops are stripped therefore, need new screws’

(Just to pick on you a little) Sounds like you are avoiding the issue. J
I would ask you to measure # of turns from bottom but you can’t turn those screws.

 

Too lean on the pilot screws, which would be why you are expriencing lean conditions below 3000 rpms. Thats the rpm band they cover.

 

If the pilot screws are stripped, how did you remove them to clean the jets?

Your carbs are not completely clean, and the popping does indicate that you are running lean.