Throttle/idle

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Jun 20, 2007
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#1
I just bought a used cr 125 and the guy I bought it from has the throttle/idle set so that when you let off the throttle the bike dies. He said he did this to keep from fouling out plugs. How can I adjust it back so that it will idle? Any help appreciated.
 
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#2
Quite honestly, that sounds a little shady to me. It shouldn't foul plugs if it's tuned right.

However, if the idle is actually just set too low, the idle adjustment screw can just be turned in (clockwise) a bit. This is the screw on the side of the carb near the slide. Not to be mistaken for the idle mixture screw which should be located near the back of the carb by the intake.

Good luck... :cool:
 
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#3
I have usually had to set my idle faster than normal to not foul plugs. On some bikes, I've set it to not idle for other reasons. I guess his thought is that "If it's not running, it can't be fouling."
Sounds like he was trying to avoid the root cause of the problem.
 

IndyMX

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#4
If you idle a 2 stroke too long you will foul plugs.. Why on earth someone would want to idle a 2 stroke is beyond me.

When I stop long enough to need to idle, I just kill it and restart. If the bike is right, it shouldn't take more than 2 kicks to get it started.

Anyway, on a 97 CR125 the idle screw is on the "choke" knob. twist it counter clockwise to increase the idle speed.

Ideally you should have just a few seconds of idle time, more than this and your throttle response won't be as crisp and you will tend to foul plugs quicker.
 

darringer

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#5
If your jetting is correct, a 2 stroke will idle for extended periods without fouling plugs. An idle is useful for someone learning to ride, and is almost mandatory if the bike is used for tight trails and hillclimbing. Carburetors that bleed raw fuel through the choke instead of having a dedicated idle circuit (Keihin PWK, for example) make it harder to achieve a solid idle.
 
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#6
sweet thanks for all the help. i am new to 2 strokes and well to dirt bikes and am still learning and we do ride alot of trails so the idle is kinda important to me. i'll see what i can do.