2007 CR125 Project and Tear down Thread

Hello all,

I have begun the tear down of my recently purchased 2007 CR125.  It has been ridden once since I purchased it.  The piston is about to go (approx 50 psi on compression test).  I have already submitted a few questions on TT, but thought it would be easier to pull them all into one thread.  Here are the most recent threads about the build and from here on out, I will just post questions and relay my progress here.  

The other day, my son removed the engine as we are going to replace the top end (still stock OEM, engine has never been opened).  Naturally, I have to clean the entire bike now since the engine is out, but that is a bit later.  While I am replacing the top end, I am going to go ahead and replace seals and all gaskets (minus splitting the engine).  As I was starting to tear down the engine to look at the condition, I notice that the fly wheel has some rust on it, which is not good (see pic below).  Question is, should I just try to remove the flywheel, clean it up really good and reinstall or replace it all together?  It seems mostly surface rust.  It looks like maybe some moisture got in through the cracks in the rubber wire cover around the case boot area (see pic).  I need to address that as well, but it appears the only way to fix it is to get an entirely new wiring harness which is $400!!!  Any thoughts and comments would be greatly appreciated.  

Unfortunately, I will be away from the bike for 10 days (Traveling to Ireland), but plan to put together a shopping list from RMATV and/or Partzilla during the long flight over so the parts will be waiting for me when I return.  

More progress to come!!

 

 

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Edited by TPA-MX

was this the one on Craigslist with monster graphics? I remember that was a pretty stock looking bike.

was this the one on Craigslist with monster graphics? I remember that was a pretty stock looking bike.

Yep! In Orlando area. Pure stock.

Bump for input on the flywheel.  I was thinking of just removing it...giving it a slight sanding with super fine sandpaper and reinstalling.  Thoughts?

 

Tear down completed for cleaning, bearing inspection and re-greasing.  Most bearing areas look really clean with some grease still intact.  However, I am going clean and re-grease anyway.  

After I took this pic, I was thinking....should I go Powder coating??  Hmmmmm.....  lol...

 

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Bump for input on the flywheel.  I was thinking of just removing it...giving it a slight sanding with super fine sandpaper and reinstalling.  Thoughts?
 


Yeah I'd run it like you're thinking.
Tear down completed for cleaning, bearing inspection and re-greasing.  Most bearing areas look really clean with some grease still intact.  However, I am going clean and re-grease anyway.  
After I took this pic, I was thinking....should I go Powder coating??  Hmmmmm.....  lol...
 
IMG_0856.jpg.5ae51af3691f8e68648aec530f4a198c.jpg


I wouldn't powder coat but I like the standard look so to each his own.

 

I wouldn't powder coat but I like the standard look so to each his own.

Agree. Going to clean it up this weekend and get some mother’s on it. It should look like a brand new bike!!

Got a 07 on the bench now with tranny problems 

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White diamond polish is the best I've ran across. Used it on some VTX wheels, worked really well

White diamond polish is the best I've ran across. Used it on some VTX wheels, worked really well

I used some Napa aluminum brightener today then went to town with some mothers. Will finish it up tomorrow and post some pics.

 

My son should be completing the top end this weekend as well, then reassembly, cleaning and regressing as I go. More pics to come.

 

 

Ok, we have one cylinder head bolt that is being stubborn. Any tips on how to get it off? I’m afraid that it’s going to strip. It sucks that it is in a spot that a regular socket head will not go, otherwise I would use my air gun.

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26 minutes ago, TPA-MX said:

Ok, we have one cylinder head bolt that is being stubborn. Any tips on how to get it off? I’m afraid that it’s going to strip. It sucks that it is in a spot that a regular socket head will not go, otherwise I would use my air gun.

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12mm box end wrench :thumbsup: 

Thanks! They are holding a set for me at autozone!

12mm box end wrench :thumbsup: 

To confirm, box end wrench is the same as a 6point right?
7 minutes ago, TPA-MX said:

Thanks! They are holding a set for me at autozone!

When you get it off can you post pic of piston please. Currious to see if lube holes are in piston. Honda seems to be the only brand anymore that i have to drill holes myself in  stock pistons 

 

Edited by Motox367
When you get it off can you post pic of piston please. Currious to see if lube holes are in piston. Honda seems to be the only brand anymore that i have to drill holes myself in  stock pistons 
 

Yep, of course. I have the new piston I can post a pic if that will work for you, that would be faster.
8 minutes ago, TPA-MX said:


Yep, of course. I have the new piston I can post a pic if that will work for you, that would be faster.

What brand? 

What brand? 

Oem.

 

Pics of the cylinder coming tomorrow. It’s soaking right now.

 

Here is the original piston from the engine.

 

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So, a quick updater.  the seized bolt had to be chiseled off with a 3/8th chisel and hammer.  It finally broke loose.  The guy at AutoZone had no clue what he was talking about and held a 12 pt. socket set for me....ugggg

None the less, got the cylinder off and replace the piston in a few minutes.  Removed the power valve assemble and soaking the valves and the clyinder overnight for a good cleaning.  Good cross hatching marks on the cylinder with no vertical etches.....feels smooth.  As mentioned, pics will be posted tomorrow.

I finished up polishing the frame...wow that was a hard job.  Anyway, first time working on a frame...but I think it came out pretty nice.  I know it wont stay looking like that for long, but it sure does look pertty today!  

 

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