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Complete rebuild or not

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My son has a 2002 Yz125 that he got about 2 years ago, supposedly "rebuilt" just before he got it. 

Its always started and ran good until 2 weeks ago when it lost compression wile riding, anyway took jug off

and found the piston ring broke and some decent wear in exhaust port area. While I'm sure I can get away

doing the top end my is should I just go through the whole engine. Lower rod bearing seems good

and don't feel any crank (I know, you don't really know until its opened up) We are stripping the bike 

down since its late in the season and going to send frame out for powder coating, new rims, bearings and giving the bike a true 

go through. My first thought is a complete engine tear down since we are going this far, or am I over thing it ?

Any thoughts as to which crank kit if I go that way ? I've used a Hot Rods crank kit on his KX65 years ago but 

sold it shortly after so have no idea how well it held up. 

Wear on the piston (obviously) exhaust port area. Thanks in advance

YZ125 piston.jpg

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If you are going that far, yes!!!

Do this to it:

IMG_5898.JPG.55d1d240ce36c0aecbbad4e8f4316902.JPGIMG_5902.JPG.b51a2e07603ee933c08a5de4f1b06b14.JPG

2002 YZ125, Polisprort upgraded 2015 /\ plastics w/airbox kit, light speed fork guards w/CR style brake routing, Light speed carbon fiber frame guards, PC black hubs/rims, Etc. etc. etc.

But, who am I to purswade you to do it. This bike was such a virgin in only needed a top end. But I do all seals OEM, gaskets ProX. Show this picture to your boy, let him decide how to spend your money. :goofy:

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P84, he has no problem figuring out how to spend my money just like most kids :rolleyes: What's this air box kit ? Does it serve any purpose besides cosmetic ?

CR style brake routing ?? Never heard of these.  Nice looking bike BTW

I have a feeling he's going to pick some off the wall powder coat color but oh well

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5 minutes ago, copenrc said:

P84, he has no problem figuring out how to spend my money just like most kids :rolleyes: What's this air box kit ? Does it serve any purpose besides cosmetic ?

CR style brake routing ?? Never heard of these.  Nice looking bike BTW

I have a feeling he's going to pick some off the wall powder coat color but oh well

It's the upgraded air box installed on the 2015 up bikes. (cosmetic) Complete plastics kit with it OEM or aftermarket from Polisports. You need to have a rivet gun for three rivets on the little mud flap in front, and change the boot out. 

http://www.ebay.com/itm/POLISPORT-RESTYLE-PLASTIC-KIT-YAMAHA-YZ250-YZ125-2002-2014-UPGRADE-TO-THE-2017-/282452288250?epid=823555936&hash=item41c377e2fa:g:Mk8AAOSwjL5ZA~wd&vxp=mtr

Comes in OEM, black, white, and now yellow.

Honda had the patent to run the brake line inside the fork, down to the caliper up to 2004. It's cleaner, and cosmetic as well. 

Color is as close to OEM as poss. And don't worry, all colors look pretty sweet. 

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For the crankshaft, I would send out the current one, if it is OEM, to be rebuilt with a Pro-X rod and balanced. Some people have bad luck with aftermarket crankshafts, and you can't go wrong with OEM generally.

If you are thinking about the restyle kit, you can find white, black, and blue on ebay for around $130 or $140 with free shipping. The fluorescent yellow kit costs $170, still cheap.

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8 hours ago, P84ONE said:

It's the upgraded air box installed on the 2015 up bikes. (cosmetic) Complete plastics kit with it OEM or aftermarket from Polisports. You need to have a rivet gun for three rivets on the little mud flap in front, and change the boot out. 

http://www.ebay.com/itm/POLISPORT-RESTYLE-PLASTIC-KIT-YAMAHA-YZ250-YZ125-2002-2014-UPGRADE-TO-THE-2017-/282452288250?epid=823555936&hash=item41c377e2fa:g:Mk8AAOSwjL5ZA~wd&vxp=mtr

Comes in OEM, black, white, and now yellow.

Honda had the patent to run the brake line inside the fork, down to the caliper up to 2004. It's cleaner, and cosmetic as well. 

Color is as close to OEM as poss. And don't worry, all colors look pretty sweet. 

Yes Yamaha breaks much better after then lol so were everyone else's tho . I need that kit for my 00' . Brake sucks on that bike reminds me of my Kawasaki spongy brake days. All cause of the routing I believe.  That bike is sweet Doc :thumbsup:

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Just now, Motox367 said:

Yes Yamaha breaks much better after then lol so were everyone else's tho . I need that kit for my 00' . Brake sucks on that bike reminds me of my Kawasaki spongy brake days. All cause of the routing I believe.  That bike is sweet Doc :thumbsup:

Thanks, she was a looker. All that matter was it caught the eye of a 13yo and dad had to pay for it.

Hey, you want me to mail you a set of Light Speeds? Bet my shipping is cheaper than theirs, and I can just walk into the shop and pick them up.  

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3 minutes ago, P84ONE said:

Thanks, she was a looker. All that matter was it caught the eye of a 13yo and dad had to pay for it.

Hey, you want me to mail you a set of Light Speeds? Bet my shipping is cheaper than theirs, and I can just walk into the shop and pick them up.  

Honestly I don't ride that bike enough not really worried about it but man thanks for the offer appreciate that :thumbsup::thumbsup: if I decide to race it tho I did think about it other day when had out. I'll be taken you up I that most definitely buddy. Again thanks 

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Maybe,
Is there a easy way to tell if the current crank is stock or aftermarket. It sounds like a crap shoot getting a good aftermarket crank kit from what I've heard and read

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