Topic: RPM's drop really slowly or not at all

[Saml01]

I have Mikuni VM32's on my CB360 and im having a #$%* of time getting it to run right.

Mainly it behaves like the throttle sticks. I turn the engine off, and the throttle twists completely fine.  Start the engine and the throttle gets heavy. Almost like when the engine is running it doesnt ever return to its closed position. If I rev the engine it just hangs and very slowly comes down, or sometimes not at all.

[mlinder]

Carb boot air leak or sticking throttle cable (or bad carb synch).

[Saml01]

Carb boots new, carbs are synced.

cable sticks when the engine is on but doesnt when engine is off?


P.S. Next bike, digital fuel injection 100% #$%* this noise.

[mlinder]

Boots new doesn't mean boots installed correctly.
If boots are not installed correctly, synch is not correct.
That being said, try rerouting your cables.

[tbpmusic]

I have Mikuni VM32's on my CB360 and im having a #$%* of time getting it to run right.

Mainly it behaves like the throttle sticks. I turn the engine off, and the throttle twists completely fine.  Start the engine and the throttle gets heavy. Almost like when the engine is running it doesnt ever return to its closed position. If I rev the engine it just hangs and very slowly comes down, or sometimes not at all.

360's have a push/pull cable system.
How did you adapt that to Mikunis??
Or did you rig something else??
Maybe the cable doesn't have enough "throw" ??

[Saml01]

I have Mikuni VM32's on my CB360 and im having a #$%* of time getting it to run right.

Mainly it behaves like the throttle sticks. I turn the engine off, and the throttle twists completely fine.  Start the engine and the throttle gets heavy. Almost like when the engine is running it doesnt ever return to its closed position. If I rev the engine it just hangs and very slowly comes down, or sometimes not at all.

360's have a push/pull cable system.
How did you adapt that to Mikunis??
Or did you rig something else??
Maybe the cable doesn't have enough "throw" ??

New cables, and a new throttle tube.

They def have enough throw because I have room to adjust them.

[w1sa]

If all above is satisfied (secure sealed carb boots, throttle cable friction/routing etc) and all other tuning aspects are within spec, I would vacuum sync the carbs again.
Pay attention to individual idle screw and air/mixture settings to try and achieve a final vacuum balance while at the same time achieving a balance of mixture strengths and reasonable idle screw settings which allow the engine to idle steadily at the desired rpm/temperature.

Having said that if the rpm (still) sticks it could also be drag between the slide and the carb bore which might be increased when engine is running due to operating vacuum, return spring strength?...etc.

Are the carbs new/unused?   Are the bores clean and blemish free?   

[Saml01]

If all above is satisfied (secure sealed carb boots, throttle cable friction/routing etc) and all other tuning aspects are within spec, I would vacuum sync the carbs again.
Pay attention to individual idle screw and air/mixture settings to try and achieve a final vacuum balance while at the same time achieving a balance of mixture strengths and reasonable idle screw settings which allow the engine to idle steadily at the desired rpm/temperature.

Having said that if the rpm (still) sticks it could also be drag between the slide and the carb bore which might be increased when engine is running due to operating vacuum, return spring strength?...etc.

Are the carbs new/unused?   Are the bores clean and blemish free?   

You cant vacuum sync mikuni slide carbs, I mean you can but there is no vacuum nipple to tap into.

I did some reading on another site, and it mentions that if engine rpm fails to return at idle its due to an undersized pilot jet.
Once I sort out a bunch of other problems that just came up, and that doesnt resolve the issue I will try a richer jet or the one I had originally.

I will be pulling both carbs and examining them for any sort of damage, maybe something is holding them up.

[crazypj]

you do have some slack in cables?
PJ

[Saml01]

FYI

Lean pilot causes this condition.

Just in case someone asks in the future.