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Decompression lever free play for 250R

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My new-to-me '02 250 won't kick start anymore. Roll starting works but I'm getting some sputtering & backfiring... but only when I let off the throttle. Runs fine as long as I'm on the gas. Idle is finicky & the motor dies unless I set the idle higher than it needs to be. Spark plug looks good, although possibly indicates a slightly lean condition. Carb, jets & air filter are clean.

I figured I'd better check & adjust the valves, since I hadn't done that since I bought it, so I did. The exhaust valves in particular seemed to be the most out of spec. Manual states I need to adjust the free play for the decomp lever 3/16 to 5/16". I pull the lever & I see motion where it connects to the motor no matter how I adjust the nuts. Am I wrong to compare this to the "free play" I might notice in my clutch lever? I'm confused. :)

I want to make sure I get the decomp right before I kick her over since I've read I can screw up the valves if it isn't correct.

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It's 3/16 to 5/16 at TDC; there's no way to get a meaningful adjustment otherwise. I recommend checking it at full right and full left turns too. That cable has a complex routing.

I would be looking at the pilot jet for the idle issue.

If the pilot is clogged it will start on full choke and rev, but not idle without the choke, and even then it won't really idle. In other words, the choke is supplying the only fuel instead of the pilot. I know you said your carb is clean, but all it takes is a insect part in the pilot.

You could certainly back the mixture screw out a bit (to richen) if lean is suspected.

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It's 3/16 to 5/16 at TDC; there's no way to get a meaningful adjustment otherwise. I recommend checking it at full right and full left turns too. That cable has a complex routing.

I would be looking at the pilot jet for the idle issue.

If the pilot is clogged it will start on full choke and rev, but not idle without the choke, and even then it won't really idle. In other words, the choke is supplying the only fuel instead of the pilot. I know you said your carb is clean, but all it takes is a insect part in the pilot.

You could certainly back the mixture screw out a bit (to richen) if lean is suspected.

Thanks for the advice. I'll check everything you suggested today.

About the freeplay in the decomp lever... can I measure that by watching for contact in the RH exhaust valve port?

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It's measured at the tip of the lever on the handlebar. There may be other effective ways, but this is the "official" procedure.

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It's measured at the tip of the lever on the handlebar.

Yes, but the lever pressure feels constant right from the word go. Watching the mechanism make contact in the RH exhaust port, I then measured how far the lever travelled when released & adjusted from there. I'm fairly certain I have it correct now.

Turns out my main problem was the plastic baffle that goes over the main jet. I had to lay the bike on it's side today to get the baffle to stay where it's supposed to go & then put the float bowl on. Is the baffle supposed to be so loose that it won't stay put with the bike upright?

Anyway, my XR kickstarts & runs like it should now. I couldn't be happier. :)

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