Low power with throttle

[ekabil]

Hey guys,
Carbs were just rebuilt, new o rings and all, and then synced without too much hassle. Bike ran awesome, better than ever, for three riding sessions over the past 2 weeks following that. Then yesterday I start her up and starts up pretty normal, but it's harder to get RPMs up as the bike warms up. If I gave it throttle, the engine would get all muffled sounding and RPMS would decrease. once the bike was running smoothly at idle without choke, I tried to drive around the parking lot. I could putt around at low throttle, but it ran kind of "jerky".. BIP bip bip BIP bip bip... the jerkiness occurred regularly in time with the engine.
sounded pretty normal at idle in neutral, just a little quieter than usual.

Also, I get 12.5 volts at idle (I have a permanent voltmeter hooked up to the battery back from charging system issues) during all this, when I used to get a bit over 13 at idle and 14 at speed. I am not sure what this means.

after syncing 2 weeks ago I noticed that the bike was slow to return to idle, and would climb in RPM as the engine warmed up. to compensate I richened the mixture a 1/4th turn, which made it run perfectly, at least until yesterday.

So what would you recommend as the next step? What are some basic things to rule out, and how should I rule them out?

thanks!!!!!!!!!!

Emmad

[tom203]

that "new o-rings and all" stuff - so you replaced the boot o-rings at cylinder head too?

You sorted out your charging issues, but suddenly you get 12.5 volts at idle- what happens as revs go up?

[chuck hahn]

Go back and check all the connectors under then tank...sounds like maybe you jiggled one loose when removing or installing the tank..Jerkiness may be from coils misfiring from the lowered ignition voltages.

[ekabil]

so you replaced the boot o-rings at cylinder head too?
Negative. I stripped the bolts trying to impact wrench the boots off, was unable to remove the boots. thats the one thing I tried to do but couldnt. I heard you can check for air problems with some starter fluid sprayed around the intake boots. this doesn't completely r/o o ring breakage, although if the test is positive then it definetly means air leakage. ill try this when it quits raining

[tom203]

At a minimum, replace those boot o-rings- this might have caused the creeping idle when warmed up. But this would not cause the jerkiness- which sounds like misfiring like chuck said- maybe loose wires or your charging system ain't producing enough.

[Dave8338]

At a minimum, replace those boot o-rings- this might have caused the creeping idle when warmed up. But this would not cause the jerkiness- which sounds like misfiring like chuck said- maybe loose wires or your charging system ain't producing enough.

I agree.

Also if the screws are stripped, get a needle-nose vice grip and clamp on the heads of the screws that you can reach. Using a hammer, tap on the grips counter clock-wise and those screws will loosen right up.

Once you get one out of each boot, take a small block of wood and tap counter clockwise on the boot itself with the wood and hammer and the other screws will loosen, as well.

Good little trick that has yet to fail me.