KLR250 Misses At All Engine Speeds

This '97 KLR250 will start, has a steady missfire at all engine speeds. It is missing so badly that it can't be ridden. The carb has been apart and carefully cleaned and inspected twice. The CDI box has been replaced with a used unit off a KLX. We have a 2nd used CDI box that has been tested, but made no difference. We checked the valvetrain, compression release arms for free travel, camshaft and set the valves. Plug has been replaced too. The only thing that has not been done is check the stator.

Does anyone have any idea what to check next?

How old is the fuel, and could there be water in it?

That's all I can think of at the moment, but have you considered this post for the general forum? A wider audience could make for more responses and ideas...


The only thing that has not been done is check the stator.

Does anyone have any idea what to check next?

Timing? If it runs, the stator is at least ok, but is it bolted down in the right spot?


We replaced the fuel tank Torch - new fuel. I guess it could be timing, but causing an engine miss? Seems more likely that timing would cause it to be either very sluggish or spark knock heavily. I will post in general tech form as you suggested. Thanks.

Hi Hinterlander does it idle ok but as soon as you try and take off it seem to bog down wildly as if you are in sixth gear...can't get revs up?

No idle at all, must use part throttle just to keep it running. At part throttle, it misses really bad, almost sounds like it is firing every other compression cycle. The bike can't be ridden like this at all. We've gone through everything except for the "exciter" listed in the manual, that's next. I would suspect the carburetor, but my brother is an outboard mechanic and went through it twice setting everything to factory spec from the factory manual.

I'd make sure the carb diaphragm is fully intact, no leaks and fully sealed; be sure the "choke" (starting enrichment system) plunger seats fully; and . . . check to see there's no intermittent sticky valve . . .

Any of these areas could be the source of the symptoms described.

Beyond these areas and those previously mentioned, other than some intermittent electrical breakdown (e.g., arcing, short or open), don't know where I'd turn . . .

Good luck!

If you have a kick stand switch make sure it is disengaging..To check if the switch is faulty trace it back to to the connectors usually under the seat area on the right hand side..Disconnect the switch and join the connectors on the loom side together,they are usually male and female..This basically bypasses the switch...If this circuit is faulty it will electronically disrupt the the engine management so the bike will barely run and will backfire and will not let the engine fire correctly..hope this helps

Sounds electrical - check the integrity of the spark plug lead and boot. and the connections to the CDI. maybe just replace the plug lead wire altogether.

I bought a basket case KLR 250 that I completly rebuilt, the bike was easy to start but missed like crazy and had no power. After going through EVERYTHING I found the timing marks dint quite line up (this was only by a few MMs on the stator), I replaced the cam chain for a new one and all was perfect.

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