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1985 RM250 bogging issues

327 Views 4 Replies 2 Participants Last post by  jaguar
Hello, I'm struggling to find some good help with this old RM250 it's a 1985 we got as a project to restore for my dad.
Currently it has a new top end .030 overbore carb off of a newer rm. Clean new jets 170main 55pilot starts right up first or second kick
It has zero umph on bottom end there is a very gradual grade in our yard and if I try to pull out from bottom of yard it won't pull, I have to keep rpm up and ride the clutch to get it up through the yard.
Once you are able to get it going and rpms get up it runs great and pulls hard but low end is garbage,
I'm at a loss hoping there's some old school gurus that can help
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Usually that problem is leaking left crank seal. On old bikes you also have to inspect the needle jet to make sure it isn't wallowed out due to needle vibration over the years. SUDCO is a good source for a replacement. Their email is [email protected]
Hadn't thought of crank seal guess it makes sense of it's sucking air causing a lean condition, but wouldn't it be lean causing running issues all the way through rpm range? Only weak on bottom end of you can get rpm up it takes of.
@jaguar thanks for the reply by the way
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