1996 RM125 JETTING: CHECKING YOUR CHOKE SYSTEM
My 1996 RM125 acts funny when I use the choke to start it. It idles really high, like I am holding the throttle 3/4 of the way open, even though I’m not even touching the throttle. When I turn the choke off, the idle drops back down and it idles fine. What’s the problem?
As rule of thumb, bikes always gain rpm when they are first started on the choke circuit. On the other hand, they should not rev wildly. Based on your description, we would guess that the seal on the choke plunger is worn out, causing an air leak when the plunger is pulled out. This also explains why the bike returns to normal when you shut the choke off. You need to tear your carb down and replace anything that looks wore (pay special attention to the slide).
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