Yz 125

nitrofish

nitrofish

PR Addict
Unless the deal falls through I may be the proud owner of a 05 YZ 125! I know, a 125? It is what I was riding when I retired back in 90. 2 stroke screamer, pinned and clutch like he*#! I have been out of the big bike scene for 20 years, been learnin' the boy and pit biking. Any set-up tips or things to look for on this thing would be appreciated. Thanks in advance. MW
 
Awesome!.....more 125 pilots !!!!!
The YZ's are pretty tough, as long as it doesn't looked beat on you should be good to go.

I LOVE my YZ-144....!
 
Good, solid bike. The 05s were new motor, new frame, and Y nailed it the first time out. About the only issue I have seen is once in a GREAT while the clutch lifter rod (that passes through the mainshaft of the engine) will crack. The culprit is usually traced to the two needle bearings that support the lifter arm in the LH centercase. I't an easy fix.

Stock jetting was really good, too. Make sure the top end, fork seals and air filter are good, then ride it. I am rebuilding a 2003 model. I am looking forward to seeing and hearing more of these little bikes at the races.
 
they are also notorious for cylinder head detination as well. mine runs like a raped date, but had problems with detination cuz of pump fuel. 100 or 110 octane usually takes care of it.
 
You have to replace the stopper lever or some call it the shift stopper that's behind the clutch basket. Those go bad they fixed it in 06 but the things have little bearings on them that come apart. This is a known issue forsure and when you order they new part you automatically get the updated part. You can replace it by just pulling the basket off but it's a pain in the ass and requires some muscling and prying. Or you can take apart that whole side and do it.
 
Just go on thumpertaLk and search "replace your shift stopper" and a giant thread will come up on it with some instruction and pictures
 
Good info! I have done some searching myself. I am curious about upgrading to a 144. Is it best to buy a kit or bore, if you can use stock cylinder. What brands are best? Thanks. Matt.
 
I would get in touch with Eric Gorr at Forward Motion (630-825-5645) and send in the OEM Yamaha stuff.
He will strip the cylinder, increase the bore, re-pate the cylinder, port the cylinder, cut the power valves, re-shape the head, give you a piston, ring, small bearing, and wrist pin. Just bolt it all together and go!
 
baxterj787 said:
Good, solid bike. The 05s were new motor, new frame, and Y nailed it the first time out. About the only issue I have seen is once in a GREAT while the clutch lifter rod (that passes through the mainshaft of the engine) will crack. The culprit is usually traced to the two needle bearings that support the lifter arm in the LH centercase. I't an easy fix.
Click to expand...

This will only temporarily fix that problem. THe real problem is the inner clutch basket and pressure plate have worn past spec. The distance between the actuator rod ( in the LH case ) and the pressure plate has become to short and the excess pressure on that needle bearing causes premature failure. Just an FYI as I have repaired 3 bikes with this same problem.
 
Oh yeah, 125's --- everyone's doing it!!!

Here's my RM125 with 144cc Eric Gorr topend.

MuddyCreek003.jpg
 
After I rode Sharc's bike, and mine went kaboom, I've actually looked around a little for a cheap yz 125. I can't believe I just said that.
 
Nice Rm Pit, 89 RM 125 my last ride 21 years ago. I think this calls for a new thread. Post your glory days pics, 2 stroke in action or on the crate (yeah milk crate, remember when we had to build our stands) My problem is the pics are not digital, I will have to snail mail em. :)
 
Jon16 said:
After I rode Sharc's bike, and mine went kaboom, I've actually looked around a little for a cheap yz 125. I can't believe I just said that.
Click to expand...

I can't believe you said that either based on the last time I saw you on a YZ125.
 
We have a 98 YZ125 in the garage. It has been a fun bike to ride. We need a cylinder for it to get it up and going this year. My son railed on that thing. I would love to get it going.
 
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