I recently acquired a beat ‘94 CR125. It’ll be my son’s first run at a full rebuild, and I know it makes zero financial sense. However, the ‘94 was my first dream bike as a kid.
I got the cases split and blasted, and I need to probably send the cylinder off. The piston was seized and the bore looks a little rough, but not as bad as I expected. After a light cleaning with muriatic acid, I’m getting an bore ID of 53.87mm, but the standard for an “A” cylinder is 53.976-53.983mm. Is it typical for a used cylinder to measure smaller than spec? Maybe there’s a thin layer of aluminum on the walls?
Either way, who are some good shops to use for boring, sleeving, or Nikasil? It’s been a long time, so I forget what the options are on a rebuild.








https://millennium-technologies.com/
Great work so far.
If you're considering port work also, I would highly recommend Tom Morgan Racing. He can also have your cylinder plated at Millenium Technologies after his work. If no porting, then maybe straight to them. But would be sure to confirm if they need the piston you plan to use before plating.
Yes, I was going to ask about the piston. In a perfect world, I’d like the shop to provide a piston to match the bore, otherwise I would just buy their recommended size after the work is done.
I tried my hand at boring out an old junked XR cylinder with poor results. I’ll leave the precision work to my betters.
TMR for anything engine related….. note: I learned while performing a top end on my 93 CR125, the B pistons of this era measure smaller than the A pistons….this is opposite of what most is common….My 93 has a B piston and cylinder Stock, all after market pistons that I could find were A pistons…IE..slightly larger. I actually bought a ProX A piston and it was too tight in the cylinder…so I have to use stock Honda B pistons until my cylinder wears or I have it machined for aftermarket A pistons….confused yet?
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If you want to send it to millennium technology you can send it out to them and I can get you a 15% off any labor.
They can repair and replate it l, cut and set the head for it. You can even have them port it. I believe alot of their specs were set up by Eric gore and tom morgan.
I will say if I was building a 90's Cr 125. 93-97 especially it would be Bills pipes. They worked alot with HRC and team honda.
Thanks, but it’s probably too late. I just sent it off to them this morning.
I agree. I’m on the hunt for a Bill’s set, but I don’t think they make them anymore. PC and FMF still do, but all you can get new are nickel plated. PC has the works on back order, but I’ve also had a pipe for my RM on back order for a year now.
Give bills a call or message them on IG they still have stuff for those bikes. They will also make your silencer with a stinger if you want.
If you sent it in with the paperwork maybe. If you wanna DM me ur contact info I can call them and ask. Never hurts to try. Up to you.
Bill built me a pipe & silencer for my 04 cr125 a few weeks ago. It only took aprox 2 weeks. Milenium plating & repair is the best but pricey now. Get plating done 1st then porting. Because plating process puts a shade of color ovr the porting. Milenium talked me into using wossenger pistons. They a high quality plating will match the piston perfectly, also hv numerous piston sizes. Work them for a 5 piston deal , aprox 500 bucks with an extra ring. 94 TMR cr125 test on yt thst bike was a ripper . Close to a mod 2025 bike. Very competitive bike yet . Race the 12+ age group 125 class , you,ll hv a blast.
Not sure what you’re laying down in all of that bro….l
When @profeshenal125 speaks, sit up, take a sip of coffee, and take notes. The man doesn’t have time to waste.
There are multiple builds on YouTube of early 90s CR125s featuring Millenium plating and Tom Morgan porting. I had no idea.
That’s cool, but they told me they don’t have the jig for the 94 anymore. I was about to get a Fresco from Italy, but went with the PC Works instead. The PC Works has been on backorder for a long time and it showed in stock when I randomly checked last night. Fate.
I did get a call from Millennium. They are able to repair the minor damage to the head. I didn’t know about the 5 piston package, but they’re providing a Wossner, and I have a Wossner crank assy.
Thanks!
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