The CR125 Project: CR125 Top End and Re-Assembly

Sunday, February 3, 2013

CR125 Top End and Re-Assembly

I finally have all the parts assembled to put the top end back together and make this bike look like it belongs in one piece again.

I sent the cylinder out to a company in Texas called Rat Racing and thanks to Tom it came back looking beautiful and ready to go back together. Tom helped me get the right size piston and I wanted to keep it to as close to std bore as possible so he took all the measurements and decided that we could go .5mm over and clean up the cylinder perfectly with that size.

New Base Gasket.

Cylinder on, Piston arrow forward...Ready.

These two strokes go back together pretty easy, especially after you have done a couple four stroke bikes, the only tricky part can be getting the power valve put in correctly and the one on this bike is an easy one so it didn't take long to put it together.

All bolts Torqued down with new gaskets installed, valve linkage installed ready to put the covers back on.

Valve covers on, ATAC chamber installed .

Hoses installed, top motor mounts torqued, ready for exhaust.

Stock Exhaust with a couple little wrinkles, I'm on the lookout for a nice Pro Circuit system for it. Worst part of that is I had one in my dads barn a couple years back I ran across it, now it has gone missing.

Plastics back on, looking good.

Chain and Sprockets ordered today. Have to wait a bit for money to order tires, also need to find the proper prolink decal for the swing arm and a good intake manifold because mine has a crack all the way through and the one that I ordered and got in ups yesterday is not the correct model.

After sitting on that work table for just over a year, the CR has moved to a proper bike stand and is ready for tires.

1 comment:

UnknownMarch 26, 2015 at 2:01 AM
Hi, could you recommend me engine black coat? Thanks
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The Back Story

This bike was originally purchased by a woman and her husband for some recreational trail riding. I have her name because its still on the title. They bought this bike (the 87) along with a 1986 CR125 (that I also bought) at the same time new in 1987. They proceded to ride the bikes for a couple of years as the story goes maybe three or four times a year. Then things between them went bad and they ended up divorcing in the early 90s. She got the bikes in the settlement. In 1995 She has a new boyfriend or husband and they decide to give the trail riding a try, they went out a few times but it turned out that they were over it. The bikes then sat in her garage untill Feb of 2010. Now the next owner comes along with his teen age son to purchase the bikes and use them for trail riding together. Neither of the new owner knew anything about bikes (and from the looks of just a few of the things on them I do mean they knew NOTHING about them) so the son takes off like he is invincable on the 1986 bike and procedes to ruin it from what I believe is running it without the use of pre-mix, ( I have not pulled the top end apart just yet). The son then decides to play mechanic and started pulling things apart without knowing what he is doing, so there are some small parts missing but was stopped before too long by Dad and saying they would have someone take a look at them. The 1987 bike was run some but at a much slower pace but probably still with no Pre-mix (it still has compression). So the bikes sit in a barn for some time waiting for Dad to have them looked at. It never happened, Son moved out Dad needs to move across country. After another year and a half in the barn now December 2011 I find the add on Craigs list and bang like that, I have two lightly used mid 80s CR125s for super cheap.