carburator and throttle

[Guest]

ok the problem im having is that the carburetors are tuned pretty well
but when i bearly crack the throttle open is reves up to around 4k rpm then slowly comes back down
has anyone had this problem and is their a mod i can do or maybe a new throttle spring or am i just stuck with this problem

[MisterCinders]

Throttle sticking or idle hanging?

[Reaper0001]

yes and yes

[BassCliff]

Hi,

What maintenance or adjustments have you done to the carbs? Proper cleaning? Bench sync? Vacuum balance? Has the intake been modified in any way? Airbox or pods?


Thank you for your indulgence,

BassCliff

[Reaper0001]

all has been done sync bench sync vac balance all has been done
it is running smooth but it is sticking or idle stuck

[Nessism]

Did you read though the Newbie Mistakes thread to see if anything applies?

[Reaper0001]

i think a rebuild might be in order
my uncle says he has rebuilt the carburetors if that's the case maybe i need to grease everything!
is their any other advice that y'all might have for me because i have taken cleaned and put back together the top part of the carbs my uncle says he has rebuilt them but i should ask to see if he did!

[BeerHunter]

Have you used a lower tension throttle spring, or modified the spring attachment?

Other possibility could be throttle cables are over tightened. The return cable needs to be very loose. The cables also might be routed improperly. With the idle too high turn the handlebars and see if the RPM changes.

Have you adjusted the pilot screws recently?

[MisterCinders]

An idle that climbs and stays up is either a mechanical problem (the throttle or slides kept open physically) or a mixture issue (too much air in the mixture keeps the rpms up).

To root out sticking throttle issues, try this.

First, check the cable routing for twists and snags. Then open and release the throttle while the bike is off to make sure it snaps back. Do this with the bars straight, full left, and full right. It should snap back with equal vigor at all positions.

Then, as mentioned, turn the bars while the engine is idling to see if that changes the RPMs.

If the cables are snagging, lube them, adjust them at the carb connections, and check the routing.

If the cables check out, then see if the slides are the issue. One way to do this with VMs is to remove the tops and then run the engine at idle. If the idle stays up on a blip, try pressing gently on the slide tops to see if that brings it down. If so, you have a slightly sticking slide. So pull the carbs and clean the slides (and everything else, if you haven't already). Run a bottle brush through the slide chambers and try a little WD-40 or 3-1 oil to make sure the slides move easily.

If your idle is hanging despite free mechanical movement (i.e., cables and slides are good) then you have a lean condition or air-leak that is causing the idle to hang. Cracking a throttle shouldn't leap and stay at 4,000 RPM, even with a bad air leak, so I suspect this is a mechanical problem. That said, it could be a combination of the two.