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1974 XL 250 after sitting around for any time longer then a few weeks she kills.....

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she kills spark plugs, She wont start no matter how many times I kick it over and I even tryed taking the plug out and burning anygas that happens to be on it, only starts when I put a new one in anyone know what might be the matter?

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When my bike has been setting for as little as a week, I don't even bother trying to start it until I drain/flush the carb float bowl of stale gas FIRST. You should do the same.

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same with my 85 XR100. Valve guides leak and muck up the spark plug. If it has bene sitting for a while I just take out hte plug wire brush it and put it back in. Works great.

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ah the old XL's near and dear to my heart. You may be suffering from the infamous BSPS (Black sooty plug syndrome) this is caused by weak ignition and or over rich carburation. Start by cleaning the carb and making sure the floats are set correctly, too high = rich too low =lean. Next move the needle e-clip to the 2nd or 1st position from the stock 3rd groove, this you will have to experiment with for your altitude and the bike. Lightly bottom the air fuel screw and back it out 1.5 turns. Replace the points and set them at .014, I say replace them because it is simple and a most cost effective way to eliminate poor spark (spark was weak on these even new), set the timing with a strobe light, idle the bike at 1,200 RPM and align the fixed indexer inside the left hand engine side cover dynamo plate with the "F" on the flywheel. If it still runs bad and fouls out (carbon fouled) then replace the coil, try again, if still no joy, check the cam timing by removing the points plate assembly and the cam cover, turn the motor over until the fixed indexer aligns with the "T". the cam sprocket marks should be flush with the head __________0___________ if not you will have to adjust the cam chain until it does. (This is common after someone rebuilds them and gets the cam timing off by a tooth and cause incomplete combustion and fouls out plus, runs like crap and will not idle). IF the cam timing is OK, the the only other thing left to do is check your compression (maybe do that first) if it is low, there is incomplete combustion and the result is carbon / oil fouled plug (s). This can only be fixed by a complete top end job, rings valve guide seals etc.

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the carb bowl holds a very small amount of gas.if your running cheap stuff to start with it will turn on you in as little as 5 days. when you get through riding turn your fuel off and let it run out of fuel. problem solved :thumbsup:

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yes fuel can stale - but the newer fuels are slow to do that. I let my old XL's sit sometimes for weeks at a time and start right up and don't foul out plugs. What the lad is descrbing as his problem has to do with the bike either being in a state of low compression which leads to incomplete combustion, that is a reduction in the ignition of the compressed air fuel mixture, which will carbon foul a plug and or a carburation/ ignition or timing issue.

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Dam Dave I would love to spend a day hanging out with you so i could learn some new stuff!!!!!,and I aint no rookie,but you got it covered bro!!!

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Thanks for the kind words XR Ron. I have been working on these bikes since their inception - when how they ran was "magic" I just knew they ran... LOL then auto hobby shop in HS with the the theory of the four stroke engine set solidly in my mind, well the rest is history. I love working on the old XL's. They are after all what begot the XR's - and the entire line up is legendary in performance and reliability, given they have the frequent oil changes and a clean air filter, they will run practically forever. The new CRF water cooled motors intrigue me too, they are a technological leap in performance and so far reliability too (if maintained right) the XR650R is a prime example.

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