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Motorcycle Repair/1985 Honda Rebel 250cc (idle adjustment)


Hello,and thank you sincerely for taking the time to view the question that I have regarding my 1985 Honda Rebel 250cc.The question that I have is as follows : When the idle adjuster (by turning black knob) clockwise until gently seated is reached,how many turns would you recommend counterclockwise(outward again)until it is an adequate idle setting and close to the original factory setting?Thank you again and look forward to your advice.Dale L.Meisner

Dale, do not do that!  Turning the idle speed screw just pushes the throttle open... in this case you will have a 5,000+ rpm idle speed.

You have to back the idle screw adjuster all the way off, until it loses contact with the throttle shaft arm, then turn it in about 1/2 turn or so, just enough to keep it idling until it warms up.

If you drill out the cap over the idle mixture screw, you can then back the screw out about 1/4 to 1/2 turn to improve idle mixture at idle and the part-throttle response.

I think you were confusing the idle mixture screws with the idle speed screws. Mixture screws are turned in gently to stop, then backed out a certain number of turns. The speed screw just raises the idle speed by opening the throttle plate further and further.

Once the bike is fully warmed up... like a 15 minute test drive, you can fine tune the idle speed and mixture, then you are good to go.

Bill Silver

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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