RM125 Enduro Build **Detailed, Text Heavy**

Hey everyone,

I would first like to introduce myself as I am new to the forum. My name is Donato, I live in beautiful Vancouver, Canada. I'm 21 years old and have been riding in the technical BC woods since I was 12. I would consider myself a solid B rider.

On to the meat and potatoes...

So I'm in the process of building up my trusty 2007 RM125. I bought it brand new and seven seasons later I still will ride it over anything else out there. So I decided that I want to overhaul it this year!

Over the years it has gotten the usual upgrades. As of right now it has a new engine, JD jetting kit, FMF SST/Shorty combo, 12/52 gearing, 6 oz flywheel weight, skid plate, bark busters, revalved suspension.

The last couple seasons I've really been able to wring it's neck. Consistently passing guys on 250s and 450s. Only trouble I've been having is getting it back on the pipe quickly.

The 12/52 gearing gets it spinning up fast, but every gear is 1-2 seconds long before I have to shift, before I know it I've hit 6th gear and the 450s are flying by. Also, the flywheel weight definitely helps momentum on hill climbs and overall traction, but the bike won't snap to attention unless I fan the clutch quite heavily. I'm trying to get a balance of traction, speed and snappiness.

Anyone have any gearing recommendations? Should I get rid of the flywheel weight? I have some stock size sprockets on the way for comparison (12/51) and I was going to take off the flywheel weight but after 5 years of having it on it seems to be seized on there and I will have to take it to a shop. I'm not sure if I want to pay someone to take it off if it's going in the wrong direction. Just looking for some input.

Sorry for the long post but I think everything was covered!

- Donato

I think you should keep the flywheel weight. It keeps your revs up when entering corners and if you are making a woods bike, it is a great upgrade. If you find yourself shifting too much, then make your gearing taller

Edited by CR125-TAHOE

That's what I was thinking. Anyone have an RM125 with a good gearing setup? Curious to see what others are running. Gearing is the one thing I haven't messed around other than adding a tooth on the rear. I have a feeling if I jumped to something like a 13/51 it would be too sluggish, but I see YZ and CR125s running that. Those were older 5 speed transmissions though. Decisions!

I have 13/52 on my CR125 and it pulls it fine. If you are running 12/51 now then 13/52-53 would be almost the same. So 13/51 would only be slightly taller. I think you will be fine. That bike could probably pull 13/48 if you wanted to lol.

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