Performance Mods - RM125 '01

[SurfinAgain]

My son and I just added some bolt-on mods and did a top end rebuild and they have significantly improved the performance of his '01 RM125.

Here's what we did...
* Added Bills Pipe header and silencer
* Added a V-Force Reed Cage
* Top end rebuild using Wiseco GP piston kit

We are running a 450 jet with the needle in the second clip...this could be a little rich based on Bill's Pipes testing.

This set up has significantly improved horsepower throughout the range but mostly up top were it just rips now. The engine is much more responsive as well. In fact, my son has commented that it feels like a whole new bike and that he's going to have to get use to the new power characteristics.

BTW...for you '01 owners a note on the power valve exhaust linkage rod...ours was broken and had dropped down into the case. This rod is held in by plastic retainers on both ends. The '02 version was modified and is now weld attached on the case end. We purchased the '02 version to retrofit ours so this wouldn't happen. You should do the same to avoid an expensive repair. The new version is $35 and the gasket is $8. If your bike has suddenly lost it's top end power this could be the cause.

 

[Jeff Allen]

Nice review Surf, did you do these in stages or all at once? I'm curious as to how much different the V-force is compared to stock.

 

[EricGorr]

I've had good luck with adding two sub-exhaust ports next to the stock exhaust port. It helps overrev but loses a bit out of turns. The last model that sub-exhaust ports were used on an RM125 was 1996. The later model cylinders are all cast to accomodate the extra boost ports, look through the top of the cylinder's water-jacket holes and you can see the bulges in the exhaust port casting. I use a long drill bit (1/4inch) and a 90-degree angled porting tool to make the sub-exhaust boost port.

I've also heard some good reports on Dynatech ignitions.

 

[Esp1]

Great results with the Boyesen RAD Valve on the RM125-02 over here!
Defenetly broader pwr band than the V-Force.
Use the stop-watch when testing and see the difference yourself.
The broad pwr improves lap times right away.

 

[RMtrooprider]

The same thing happened to me with the power valve rod linkage, and I to bought the 02` connecting rod. Does anyone eale`s bike spit oil out the silencer really bad, Its not mixed rich ar anything but it`s always done that. PLEASE HELP ME!!!

 

[Esp1]

The bike does run quite rich. Depending on the kind of riding you do, you would like to go dwn on the mainjet, lower the needle 1 clip and install one size smaller pilot jet.
I'm waiting on some leaner needles to try.

 

[SurfinAgain]

Thanks Eric for the tip...I'll have to look into that...

Jeff...we did all the mods at the same time. Prior to these mods it was pretty stock except for Boyesen reeds. I can't say which had the biggest impact performance as they all work together to open up the intake, get more fuel mixture in the cylinder and free up the exhaust. For you next top end rebuild, I would highly recommend a Wiseco GP piston for this bike as it help get more fuel mixture in the cylinder. Plus, it's not that much more expense than a stock replacement piston kit. The V-force works great too. Even before when we just added the Boyesen reeds we noticed more response and power across the range. So the reeds do make a noticeable difference. Also, if you are going to replace pipe and silencer DEFINITELY go with Bill's Pipes. They do a huge amount of testing with Factory Suzuki and I'm convinced that no one knows the RM125 better then they do. Besides that they are truely one of the most customer oriented companies in this business.

RMtrooprider...my son's '01 did that a lot until we rejetted and moved the clip...we also changed premix and ratio. At the same time he started riding it harder with the revs higher. All of these have helped limit the oil slick to a manageable level.