weird throttle problem

[infect]

hey now,
i got an xj 550 which i just got up and running, however it has this weird quirk to it. If i set the idle speed high enough to keep it from stalling, say 1200rpm, it will idle fine but when i rev the engine the rpm will climb to 4-6k and stay there even when the throttle is released, the only way to get the engine to come back down is to back out the idle adjuster and this causes the engine to eventually stall. I want to think this is a throttle linkage problem, but ive adjusted the linkage to the point where it is quite slack at idle position and while the cable was slack, i operated the throttle by hand and the same problem occured. help!

[newmaac]

Infect, sounds like it's not the throttle but the condition of the carbs themselves.
If the carbs are not "in sync" you will not get decent throttle response. Also check for vacuum leaks.

Take a look at the tech tips pages. There are several posts that refer to doing an in-depth cleaning of the carbs, then you follow-up with syncronizing and colortuning. (adjusting the air/fuel mixture)
The XJ 550 might use Hitachi carbs though. The links that I referred to are for the Mikuni carbs that are on the XS.
Check it out. If the info in "our" tech tips don't help, there is an XJ owners group online that sells a CD that has all the info that you will need.

[newmaac]

I think that you can subscribe at :
xj-owners@micapeak.com

Good luck. Keep us posted