Jeff Gilbert

N. Texas SP
Oct 20, 2000
I tossed a ring in my 125sx @ DW this year, bike just didn't seem to run as strong as it used to. Because of all the mud and muck and lack of water to clean the bike before taking the motor apart all I did was toss in the ring and put it back together. I did notice the exhaust port had a lot of carbon build up but I figured it'd be good enough to get me through the week. The bike ran a lot better but I did notice it was running real good one day, real bad the next and real good the day after. This week I desided I'd tear it down and do a complete top end so I did. I have never taken the power valve all the way apart but it was so nasty I figured I really had no choice but to do so. I spent the evening scraping and cleaning untill it was all shiney, lubricated it and reassembled in the cyclinder after I removed it from the dishwasher. I didn't see the little marks when I took it apart so I had to get a 2nd opinion that I put it back together correctly, thankfully I had. I've only ran the bike through one heat cycle so far but I already notice a huge difference in performance.

I do have a tuning question though. My bike, though is jetted what I figure to be pretty good, has always been a little bit of a dog off the bottom. I took some advice from another KTM owner and moved the timing just a tad to the other "little" mark, adanced if I remember right. Evenn before the topend I noticed an improvement. Are there any other tricks I can do by simple adjustments to improve throttle response? I rode a YZ167 a while back and a KX125 just the other day and both bikes had quicker rev than mine did. I won't know if that's still the case since the topend but if not, what can I do to fix the slow off the bottom revving? (I'm referring to sitting in neutral)
ps hope I'm not rambling :think:
Last edited:


Apprentice Goon
Mar 16, 2001
Charlestown, IN
The only thing I did to my '00 was to open up some plastic under the seat for more air intake. I also probably run more oil than most (20-26:1)
Running lots of oil takes a bit of patience jetting wise, but works nicely everywhere when set up right. (when not on the pipe it will spooge even if set right, jet for ride and not spooge)

My bike has always had a great throttle response at idle. It varies slightly with the fuel I use. But never has been a problem unless I try Avgas or have the jetting wrong for the day. I've had good luck with pump gas but I have ran oxygenated fuel for a year now and really like how it responds to tuning.
I can't say I can justify the price difference though. It costs more to run trick fuel than what performance I can obtain from it. If I were a better rider I might be able to justify it.
Make certain you start with your airscrew on all changes.

ps....take out your reeds and give em a good look-see.
Top Bottom