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High RPM XJ650 UNCOMMON PROBLEM

3.9K views 1 reply 2 participants last post by  tylernt  
#1 ·
Hi everybody! I recently bought a yamaha XJ650 1983. Everything works fine.
It idles normally at 1050rpm when its warmed up. But when I open throttle a bit after the bike is thoroughly warmed up the idle hangs at around 3-4k.
I've checked and its not a vacuum leak, its not the throttle cable binding.
Thing is, if I downshift correctly itll bring idle back down to normal, but as seen as i open throttle again itll start idling high again. Strange thing ive noticed which is definitely linked is that when I ride with no throttle on it keeps going. Kind of like a cruise control....


The only way I found to evade this problem is that sometimes giving a quick jerk to the throttle brings it back down to normal, until i open it back up obviously. and downshifting it till i hit idle rpm again.

So I'm getting it's fuel continuously being fed to the engine. Ive heard about the carburator slides sticking. But have NO IDEA how to fix this problem.

well anyway, here are some pics of the bike and the carbs (still on the bike)

s655.photobucket.com/albums/uu273/weissmikael/

any help to fix this problem would be greatly appreciated, thank you!
 
#2 ·
When this happens on my XS400 it means I have the idle screw set too high. Back it off and that should cure the 3-4K hangup, but your idle speed may then be too low. That means it's time to clean the carbs, as you probably have some clogged idle jets.