Cr125 im looking to buy

[Spdfrk1990]

Im going to look at a 2000 cr125 tonight that supposedly was ran with straight gas which caused it to over heat. Owner says he has the top end apart and he took it to honda who said it just needs a piston, rings, and a hone. When I go to look at it is there anything else I can check while the top end is off. Im worried maybe something in the bottom end got messed up but other then visually looking for bends in the rod im not sure what to check. Im excited to get it and work on it but want to make sure I dont have to put too much money in it. How much does a top end rebuild usually cost? Ide like to get it running for no more then 300.

 

[julien_d]

If hes telling the truth, you could get it running for 300. It's pretty hard to see the condition of the crank bearings without splitting the case though, and it is quite possible for them to overheat quickly on straight gas.

As for the top end, you can't really hone a plated cylinder. My guess would be piston/rings/re-plate and possibly bottom end work. I'd allow myself 5-600 for repairs, and if it comes out cheaper than that, great.

 

[Spdfrk1990]

So would you put the top end together first and see how it runs?

 

[julien_d]

Nope. I'd check the cylinder to make sure it's in spec before putting anything together. If it's not, send it off for re-plate.

 

[Spdfrk1990]

Nope. I'd check the cylinder to make sure it's in spec before putting anything together. If it's not, send it off for re-plate.

Ok thanks. Wheres a good place to send it?

 

[Spdfrk1990]

Im just hoping once I get that all redone and put it together the crank is ok is what I mean. Would have to take the case apart to check that I guess.

 

[julien_d]

Not exactly. Once you have the top end off you can get a pretty good idea. By turning the crank over and holding the rod, you'll be able to feel any notchy spots in the crank bearings. There should be NO straight up and down play in the crank/rod assy, although the rod will move from side to side a good bit. You can also pull the stator cover and check for play up and down or side to side by pushing and pulling on the flywheel. I'd say if the crank and rod don't look like they got really really hot around the bearing area's, you'll probably be ok.

Post up a pic of the cylinder when/if you get the bike and just about anyone with experience can tell you wether the plating is obviously shot. Any grooves or scratches that you can feel with your finger and it needs a replate. OEM plating is thin, and traditional hones just won't cut it. There isn't enough plating to hone out a scratch even if they would. They are more likely to catch on port openings and rip plating off than do any good. You can however deglaze the cylinder with a ball hone, and that will remove any deposits left over from a scuffed up piston. This can also be done a few other ways. Scotchbrite pad or some very careful appliation of muriatic acid to the plating only.

 

[_JOE_]

You DO NOT want to reassemble it with 400 bucks worth of piston and new plating only to find out the crank bearings are junk. They can come apart and ruin all that stuff you just spent 400 dollars on. I wouldn't ever trust a bearing that was run without lubrication. A few seconds could be enough to ruin them. A complete top and bottom end kit is 360 bucks, plating about 200. Peice of mind is priceless.....

That being said, I hope the bike is less than 500 bucks.

 

[julien_d]

Yep, I will completely agree with Joe on the best course of action here. However, if it were me, I'd check them before replacing. If I can't find anything that seems iffy I'd probably stitch it up and run it. Unfortunately if I don't do things that way I'd never get to ride.

I also agree on the price. 500 - 600 bucks unless he wants to have the engine rebuilt before you buy it.