2005 Yamaha YZ 125

Spagina767
Profile picture for user Spagina767
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8/27/2013
Location
Fredericksburg, VA US
Spagina767
I picked up this 125 a few weeks ago, in decent shape. I started tearing it apart today, and would like to have it finished by New Years.

A few goals:

2015+ plastic conversion
134cc or 144cc Eric Gorr motor (undecided)
KYB SSS swap, PR2 valving
Blue Excel wheels, billet hubs






I have a pretty good helper on this one!!



Does anyone have info on these burn marks on the crank? My buddy told me that the bearings are likely going bad. It's not a big deal, because while it is apart I plan on replacing the crankcase bearings/ seals, and the water pump bearing & seal anyway.

I'm tossing around the idea of a few options:

134cc kit
144cc kit
134cc kit with a 58mm crank, making it a 144
144cc kit with a 58mm crank, making it a 155

I also plan to have the cases matched, ported, with ceramic bearings.

Anyone have input on these options?

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Banana_oil
Profile picture for user Banana_oil
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Gothenburg SE
Banana_oil 11/6/2016 10:25am
11/6/2016 10:25am
Nice build! The burn marks are from assembly, my YZ125 have had them aswell.
Kx125rider 11/11/2016 4:29pm
11/11/2016 4:29pm
Dont forget to replace the shift stopper with the newer one(09 plus I believe), before then they were known to shatter and grenade the whole motor.
Spagina767
Profile picture for user Spagina767
Posts
912
Joined
8/27/2013
Location
Fredericksburg, VA US
Spagina767 11/14/2016 2:56am
11/14/2016 2:56am
Kx125rider wrote:
Dont forget to replace the shift stopper with the newer one(09 plus I believe), before then they were known to shatter and grenade the whole motor.
Thanks for the reminder! I do have that on my list. I believe 07+ is the new part.

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smashingpumpkins167 11/14/2016 12:00pm
11/14/2016 12:00pm Edited Date/Time 11/14/2016 12:14pm
Looks good. I just put sss forks on my 2002 and it was easy. They were either 2006 or 2007 and the stem in the sss triple clamps had the same measurements as my 02 stem so I used it. The shock was a direct bolt on and definitely would be with yours because it has the aluminum frame.

I went with a 134 from Eric Gorr because it only required sending the top end. He was really nice to work with. 125s are so much fun. Good luck with the build.

I haven't gotten a chance to ride it yet. I'm almost done with final assembly. I also did the 2016 airbox and it was just a direct bolt on. I just had to screw out some rivets and replace them. I bought the parts from partsfish.com and they were reasonable.

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