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new member, motor questions on a 86 xr250r.

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Hello, I am a new member to this site, but I have visited it before. I recently purchased and completely went through a 1986 xr250r, and had a few questions about the motor. Whoever worked on it before left the balancer shaft out and installed the cam sprocket backwards,plus put on a carberator from a xl250 (has an accel. pump) I bought a bottom end off of ebay and used the balancer and crank assembly (the teeth were chewed on my crank). The crank I put in has a little play in the rod bearing(enough to make noise) and I was wondering how long this thing will run without failure with the rod making noise. I was also wondering if leaving the balancer out was a mod instead of a goof, because if it is, I'll have my crank rebuilt and put that in later without the balancer(chewed teeth). I'm just getting to the point of messing with the carb, I cleaned it, it is in excellent condition, but didn't want to waste my time if I should get an xr carb. I know it's a lot of questions, but this is the only place I've seen that looked like I could get real answers from. Any help would be greatly appreciated!

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The removal of the counterbalance is in an effort to make it rev quicker - yes to some a mod.

best to find a old original carb on ebay and discard the one that was not made for your XR.

No telling how long the rod will last, depends on how bad it is, as you know it won't get better. In the meantime frequent oil changes will help and use a 20-50W.

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I would run the old crank until you can get the new crank rebuild, then you will have the option of using the counter balance shaft.

IMO if you can hear rod noise the grenade is about to go off, and that could break your cases.

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The rod that's in it now is much quieter than the one that was in it, and I am running the balance shaft now.I have seen a couple other xr's around and they made the same noise, so I was wondering if it was something I could leave alone for long enough to do it right. It runs pretty well with the carb thats on it, I figure it mostly would slow me down on top, but I don't rev it to hard anyway. I had heard that leaving out the balancer would cause early wear on the engine,is the gear replaceable on the crank? Thanks for the replies so far.

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