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'84 XR250 won't start

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I rode it about 50 miles over the weekend and it ran great. Came home, put in the shed out back. A couple of days later I rode it from the shed out back to the garage and changed the oil in preparation for riding the next day. Next day it refuses to start. Won't even sputter. Tried bump starting with the same result. I can't think of any reason that one day it runs great and the next day it absolutely refuses to even start. I didn't touch anything on it except to change the oil! It has spark (changed plug) and is getting gas. I even tried starting fluid in the air box and cylinder head. Doesn't even cough. I adjusted the valves and that did nothing. The bike had been running great and had no starting issues. Any ideas? It's a very low mileage bike that looks almost new, not a thrasher that's been abused.

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pull the flywheel cover and check the timeing on the points, and clean them... if it still has them, not sure when they got rid of those things. Might be a weak spark or out of timeing, that's my guess... or something out of timeing... also, try your flooded engine drill, just incase.

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I dont think the XR250 ever had a points ignition.

If the spark looks weak start checking ignition components.

First make sure the kill switch isnt stuck.

Then make sure the ground wire under the tank is clean. Then check the resistance between the pulse generator leads. Should be 460-580 ohms.

Next check the ignition coil. Resistance should read 0.1-0.3 ohms on the primary side (between the two terminals) and 7.4k-11k ohms on the secondary (between the plug cap and ground terminal on coil).

Then check the alternator exciter coil. Resistance between the black/red wire from the stator and the frame should read 50-200 ohms.

Remember a frame ground has to be clean and paint free. Also the ground wires on the bike are green.

Let me know what readings you get.

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It's alive! Turns out the decompression system was way out of whack. Must have been even before the valve adjustment since it wouldn't start. Don't know how that could have happened all of a sudden though. :thumbsup:

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