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Top End Rebuild - Bike Won't Start - Sound Familiar?

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Well it happened to me. I replaced the piston and rings and shimmed the valves. I took my time and did everything carefully. I didn't try starting the bike until race day. I wanted to break it in properly by warming it up and cruising the track during practice. Well i kicked it and kicked it and kicked it... and not barely even a pop. I thought I screwed up the timing for sure. I took it home and checked the valve shims and timing... dead on. Tried kicking it and kicking it with no luck. Checked the spark - good. Finally took it to a friend thinking the carb must have got dirt in it. We proceeded to tear the bike down to get that hog of carb out and carefully took it apart and cleaned all parts. Checked the timing and spark again (my buddy didn't believe i did it right), kicked and kicked with no luck. Piston must be in backwards... nooo. Finally out of desperation we put a tow strap on the handlebars and pulled it behind his 450. Started right up!

I think the oil used to rebuild may have helped keep it from starting so easily. I didn't even use that much, just dabs with my finger. Might need to replace my sparkplug.

Moral of the story is to try and bumb start the thing before you tear it down 3 times. Although i am pretty familiar with the engine now. :thumbsup:

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It starts and runs fine now. I think i just needed to be cleaned out.

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we had the same issue with a 2004 CRF240R after rebuild it would not start, checked and rechecked everything... all good still no start...

I pulled it behind my pick up, bump started it, it lit right up and ran 100%

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Rebuilding shouldn't mean expecting it start hard. I've rebuilt and started new w/ like 3 kicks. Just be careful and methodical and find a system that works. If bump starting works, I guess you gots your system. :ride:

For future reference, do start it after a rebuild in your shop, garage, living room, etc. - don't wait 'til race day. :thumbsup:

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My wife doesn't like me racing so i think she put a vodoo curse on it the day of the race.

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Would anyone be willing to explain to me how to bump start a bike?

I've rebuilt my engine with new valves and piston, blah, blah blah, so I'm not a total moron. Ok, maybe about 4% since I don't know how to bump start it if I ever thought I needed too. :thumbsup:

Thanks.

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Would anyone be willing to explain to me how to bump start a bike?

I've rebuilt my engine with new valves and piston, blah, blah blah, so I'm not a total moron. Ok, maybe about 4% since I don't know how to bump start it if I ever thought I needed too. :thumbsup:

Thanks.

Get the bike rolling pretty fast, pull in the clutch and put in gear, let out clutch and at the same time put your weight towards the rear.

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So no need to try and kick start it at the same time, the action of dumping the clutch while the bike is moving will turn the crank?

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So no need to try and kick start it at the same time, the action of dumping the clutch while the bike is moving will turn the crank?

Yes.. Usually easier to do it in 2nd gear as 1st may be too tall and lock up the rear tire (unless you are going fast enough) But I usually do it in 2nd gear with all my bikes (including cars).

If bump starting, DO NOT try to kick start it at the same time.

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