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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> 2004 Ttr250 cranks, sparks, has gas, won't fire
Post Info TOPIC: 2004 Ttr250 cranks, sparks, has gas, won't fire
7kilps9


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2004 Ttr250 cranks, sparks, has gas, won't fire
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Good morning bois. My son bought and rebuilt a 2004 TTR250. It ran rough and wouldn't shift. He split the case. Put in a transmission. Honed the cylinder, new piston, new rings, new valves lapped in and leak tested. He couldn't get it to start. It's got spark. He claims he cleaned the carb out. Timing should be right. But it won't even fire when we put starting fluid in the cylinder. If we pull the plug out and "clear the flooded cylinder " it blows a good flame back out the plug hole. But won't even cough when it's all together. I'm going to double check the valve clearances, and clean the carb again. But it bothers me that I can't get a fart or even a cough when I prime with starting fluid. HELP



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JOHNYBOY


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recheck valve timing & tappets

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mossproof


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Going back to first principles: Spark, timing, compression and fuel - you have spark, you should have compression if the rehone is right and you are supplying fuel, so that points to timing. BUT, these carbs are notorious for blockages, not just the jets, but all the tiny passages in the carb body. As Johnny suggests, I would recheck the valves and timing, then if that fails give the carb another thorough clean.
Have faith! You know it ran before, so you just have to be methodical to find the problem.
Good luck!

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JOHNYBOY


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im not telling you to do this but in a situation like this i spray brake cleaner in intake if it tries firing its a fuel problem thats what i do NOT TELLING YOU TO DO THIS YOU TO DO THIS AT ALL

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7kilps9


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Left side intake clearance was below tolerances. So I'm waiting for a shim kit. I'm going to reshim this valve, should have better compression. I'm pretty sure he didn't check valve clearance before he stuck it all together


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7kilps9


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Well good news. We reduced the size of shim the valve in question, she's purring like a kitten. We now need to clean the carb. She doesn't quite want to Rev out in on the top end. But running celebrating the victory

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mossproof


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That's a great result. Well done!

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TTRfan


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7kilps9 wrote:

Well good news. We reduced the size of shim the valve in question, she's purring like a kitten. We now need to clean the carb. She doesn't quite want to Rev out in on the top end. But running celebrating the victory

Well done and thanks for feeding back.

PS It's very unlikely but not revving out is a symptom of a timing chain being one tooth out on a camshaft sprocket.



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