Inconsistent Idling

Hey guys,

I have an 86 VFR 750FG and it's great and everything except that the idling seems to be problematic. Starting the bike, RPM's reach 1,500 and then it gradually goes to 800-1000 in a few seconds. Reving the engine is the same, when I blip the throttle and let go, RPM's go to 1,500 and go back down to 800-1000. When the engine's cold, it goes lower and sometimes stalls.

Anyone else experiencing this? I'm going to take the bike for a tune-up but it'd be great if I could point the mechanic to the right direction to begin with.

Any input is greatly appreciated.

thanks!

lorsban

 

Tightening the manifold boot clamps should be done. Most likely a very small vac leek. Carbs may need to be sync'd, pilot screws may need adjusting. Just a couple of things to check.

 

Thanks, I'll have those things looked at. I knew there was something with the carbs but I never thought of a leak causing that.

 

Sure that the throttle snaps back cleanly and that you have some freeplay at the grip ???

Possibly sticky throttle cables, but Grey's ^^^ suggestions need checking too.

 

If the bike has been standing still for a long time the idle circuits could be plugged by the green gooey stuff which used to be fuel....

Then you might have adjusted the idle speed high enough for the carbs actually fuelling thru the pilot circuits (on idle) and all weird things start to happen.

Took a while for me to figure this out even though I cleaned the carbs a few times...

Happy Easter !

Tapani
Finland

 

Fuel feeding through the pilot jet? I guess that's possible since I did increase the idling speed quite a bit to compensate for the stalling.

I'll check it out. Thanks for the tip!

 

If you haven't put many miles on it since the winter, do that. Run a couple tanks of fuel through it, then see how it does. I always have to set the idle up a bit after the bike has sat for a while, then after riding for a a tank or so of fuel, it settles in and runs better. This is on the VF500, and the Ninja 250 that I have.