A NightMare!! 2002 RM 125 or Not?

so much to go wrong there ..

BUT.. go to CMSNL.com and check part numbers.. it might be the plates for the head changed.

Dont know the bike but we did an 89 , the parts from that go through to 92 i think. and they changed less from 2000 on too

RM125's made some pretty big changes at 04. The trans is different. Plus, the power valves and cylinder have a different setup. I think that you are ok mating the 04 cylinder to that set of 06 cases. The head should be checked for squish clearance and proper squish angle. The part that I don't have a clue about is the ignition. 04 on have a different crank at least according to aftermarket part numbers. If the key way is in the same spot and jives with the timing on the 06 motor, you should be good.

I too had similar issues with my 04 rm125 build.

I bought the bike off a dude who had it posted on LetGo (go figure) as a 2002 Rm125 with a seized up motor for 300 dollars.

So taking his word for it, I immediately bought all the internals and parts for an 02. When the parts came in I started rebuilding and of course, everything fit and went together. It fired up, idled, and would click through the gears... The only issue was the bike wasn't making hardly any compression. It would rev up to a certain point in the rev range where the powervalve should open, and then fall on it's face.

So being the rookie newb motor builder I was I troubleshooted all sorts of motor-external problems that did nothing to fix the problem until I finally checked part numbers and found out the bike was an 04.... not to mention after that I actually checked and looked at the title, thinking maybe it just had an 04 motor... Nope. It was, in fact a 2004 Suzuki RM125. HA!

So in the end I ended up getting the parts for an 04, put it back together and now it runs amazing.

Now, with my little story being told, during this experience I learned a few things that might help you out..
1. The reason the motor wouldn't run right is because the difference in the rod lengths between the 02 and the 04 is that the 04 is significantly longer than the 02. I'm talking probably about 20mm.
2. The 02 came with the same size bore, but a dome top piston. When installed on to an 04 crank, it's too tall and will hit the cylinder head, not allowing it to get quite to TDC. The 04 piston is a flat top style.
3. The cylinders are also much different in the way that the powervalve is set up, making the cylinder-to-cases gasket is different.
4. The crank fits into the 04 cases perfectly fine. I am just guessing that the cranks are the same, and it's the rods that are different.

Now with these observations being acknowledged, I can safely assume that the cylinder head on the 02 is also drastically shorter than that of the 04, making the motor mounts from the 02 un-useable.

When you search the part numbers for the 04, I believe that they are the same as an 06. So I'm thinking your cylinder/ powervalve set up is fine.

The only problem I see is that you need to get a head from an 04/06 for it to run properly.

You also need to get motor mounts from an 04/06, assuming that the frames are the same.

As far as the electrical stuff goes, I don't think it is any different... but this is coming from the same guy that re-packed the exhaust thinking it would fix my compression issue.

Check the part numbers. LOL

Hope this helps!

You need to get a new cylinder head for the flat top piston.

2005 was the better head design than the 2004.

The stator should be ok since you need to match the carb with the electrics.

It's a miss match, but it should work.

You also need the 2004 head stays since the cylinder was longer.

Good luck

Like I said, total noob here. Before I started the project I had never even cracked the cases on a bike before. I learned a whole lot on this build though, Youtube was my assistant.

Not trying to hijack your thread, but here's some pics from when it was all said and done. Thing rips.






Post some pics of your progress if you get a chance. These RMs are pretty sweet bikes. Hope everything works out!