DT125R FORUM

Power on this run was 16.98 bhp.
On other runs it was 17.58. Without any mods.

@jonne123
My stock 2002 DT125R does a genuine, GPS verified 82mph. The speedo needle actually goes all the way to the edge of the clock, on a good day.
The only mod is moving, NOT cutting the "Reed switch" that plugs into the back of the speedo.
It appears to detect (by magnetism) when the speedo passes 65mph and retards the ignition. Move it out of the way, and voilà! No longer restricted!

Use super unleaded and always warm the engine up before thrashing.


Hi mate.
I'm a biker for over 35 years, I've owned a 2002 UK spec DT125R since 2004 (I love it more than my Suzuki GSX-R 750K2 and my Kawasaki KH 250 with a 350cc cylinder swap).

My bike is absolutely stock, two owners from new, low mileage. And it derestricted itself.... with a bit of help.

I've actually had it on a dyno and at the back wheel it's producing 17.25 bhp.
It revs out in top, and the speedo needle hits the stop at 80mph. I didn't trust the speedo so I used a GPS app to verify the top speed. Turns out it was a genuine 82mph.
Which is fast enough.

The dyno people checked the emissions, because I wasn't sure how safe it was to frap it, and on a standard airbox/carb/exhaust set up, it's safely rich, so you don't need to worry.

All that I've done is

1. Use fully synthetic Castrol two stroke oil
2. Warm engine well before thrashing
3. Move the reed switch (and wrap in a little plastic bag to protect it). DO NOT CUT THE WIRES!!
4. Shook the expansion chamber part of the exhaust, and sure enough I heard the rattle of a detached restrictor washer... I didn't have to cut it open or anything.

That's it.
No DEP, no high flow filter (apparently the airbox is identical to the 200cc version so it's plenty big enough for your 125), no rejetting.

I've read in Practical Classics that a well set up Zeeltronic system will get you safely up to 19.5bhp... but finding a place that sells it, and booking dyno time is a pain.

Just for your information. On standard gearing, each 1,000 rpm equals a genuine 8mph in 6th.
So despite what your speedo may say, 8K rpm is a genuine 64mph.

Good luck.