Idle Speed Increase

[Wayne11]

My 79 Special runs very well except for one problem. As the engine comes up to operating temperature the idle speed also comes up and will peak at about 2400 RPM. When cruising the engine runs and pulls nicely in the entire RPM range.

Any suggestions would be greatly appreciated!

Thanks
Wayne11

[Ken Talbot]

Generally, you would set the idle speed when the engine is warm, then use choke on setting one or two as needed to keep the engine alive until it is warm enough.

[Redbaron]

I had symptoms like this, found my mixture was too lean at idle. Cured this by setting mix screws at 1 1/4 turns out and adjusting 1/4 turn out at a time and riding until I got this dialed in. Try adjusting to hold best idle and then blip throttle, adjust mixture screws so that idle returns to same point all the time. I would suggest going richer, or backing out screws, with adjustments until this goes away. If you back out over four turns then a re-jet may be in order. HTH

[Renegade]

You may want to check the diaphrams for pinholes if the above posts do not fix the problem. The air leaking through the diaphram will mess up the fuel mixture, too.

[RiskyBusiness]

I recommend Barron's solution. I had almost exactly the same solution and idle mixture was the problem.

[scalded dog]

I had the same problem after bench synching the carbs as suggested here in the forum, I had no problem getting the carbs to idle down, with the big idle screw, at the back of the carbs. Later 'Dog