Start Up Problems With 99 YZ125

Joined
Jul 16, 2007
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#1
My dad has recently give me his 1999 Yamaha YZ125, which has been stood for about 3yrs. We have tried starting it but there is no compression in the kick atall, i can push it down with my hand with no effort. The bike will bump start and after about 10mins running it rides 'okay'. My dads mate seems to think that it is the piston. I just fort id ask on here before i start spending money on a new piston kit. Any help thanks
 

IndyMX

Crash Test Dummy
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Jul 18, 2006
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#2
No compression means you need to look at a new top end.

Tear it down and measure everything, make sure the cylinder is within spec, and check
the rod bearings.
 
Joined
Jul 16, 2007
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#3
haha i dont think ill be doin it im 16 dont touch engines haha. how much do u reakon it will cost? cheers mate
 
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#4
D4nny_mufc said:
haha i dont think ill be doin it im 16 dont touch engines haha. how much do u reakon it will cost? cheers mate
When I was 14, I was fixing lawnmower engines for $$$. Get a manual, some wrenches, and get to work. It's not that hard.

It'll cost about $125 for parts and maybe 3 hours of time, or you can pay the shop $300-500 to do the work and forever be at their mercy.
 
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#9
you should be able to do the top end yourself, just make sure you follow the directions in the manual. I did a top end rebuild on my rm 125 when I was 15. heres a great place to get the piston/rings etc.. This site has them for the lowest price I can find anywhere

http://www.funkmotorsports.com/wiseco/
 
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#11
Look at it this way. For the price a shop will charge to fix your bike, you can do it twice :)


Even if you mess up the first time you're still ok.