2018 KX250F Top End Rebuild Help

E

ezrath

I just did my first top end rebuild along with changing out a timing chain and a spark plug. I saw 2 or 3 different people post different torque specs for the bolts inside of the engine and now I'm concerned that it will not run properly. I found a owners manual that seems to have all the right torque specs but even the engine mounting torques were different and I'm not sure what to trust. I got it all rebuilt and went to fire it up, it sounded like everything was going good. I had 91 hours on the bike and was able to start it within 2-3 kicks every time. This time I was 10 kicks in and it got backfire and hurt my ankle. I threw on a boot and gave it another kick and even hurt my ankle in the boot. I stopped there and wanted to take a break to look back into it tomorrow and check my timing again but wanted to get other peoples thoughts on what was going on and where I can find a list of torque specs that I can trust.
 
jbird710

jbird710

I personally prefer to have a factory service manual when working on bikes; takes the guesswork out of it. The manual for your bike is $90 on the Kawasaki web site, but it’s cheaper than destroying an engine because you used the wrong torque.
 
2strokesteve89

2strokesteve89

ezrath:
I just did my first top end rebuild along with changing out a timing chain and a spark plug. I saw 2 or 3 different people post different torque specs for the bolts inside of the engine and now I'm concerned that it will not run properly. I found an owners manual that seems to have all the right torque specs but even the engine mounting torques were different and I'm not sure what to trust. I got it all rebuilt and went to fire it up, it sounded like everything was going good. I had 91 hours on the bike and was able to start it within 2-3 kicks every time. This time I was 10 kicks in and it got backfire and hurt my ankle. I threw on a boot and gave it another kick and even hurt my ankle in the boot. I stopped there and wanted to take a break to look back into it tomorrow and check my timing again but wanted to get other peoples thoughts on what was going on and where I can find a list of torque specs that I can trust.
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You don’t want to follow my advice on torquing fasteners. But as far as your starting issue, rechecking the valve timing is a good start, I’d also check the valve clearances. What’s the year and model of your bike?
 
J

Johnburg

ezrath:
I just did my first top end rebuild along with changing out a timing chain and a spark plug. I saw 2 or 3 different people post different torque specs for the bolts inside of the engine and now I'm concerned that it will not run properly. I found a owners manual that seems to have all the right torque specs but even the engine mounting torques were different and I'm not sure what to trust. I got it all rebuilt and went to fire it up, it sounded like everything was going good. I had 91 hours on the bike and was able to start it within 2-3 kicks every time. This time I was 10 kicks in and it got backfire and hurt my ankle. I threw on a boot and gave it another kick and even hurt my ankle in the boot. I stopped there and wanted to take a break to look back into it tomorrow and check my timing again but wanted to get other peoples thoughts on what was going on and where I can find a list of torque specs that I can trust.
Click to expand...
Hey, you're the best bike mechanic ever; congrats on the timing chain change and top-end repair! I understand that the torque requirements maze can be confusing, but you're doing a great job.
Follow the torque specifications in your owner's manual like a gold miner would a treasure map. Your 91-hour bike ride is evidence of your prowess, and the start time is in 2-3 kicks. Impressive!
 
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