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Just got a 93 kdx took it on a a ride out in it wasn't what i expected doesnt have a lot of midrange topend power and doesnt hold wheelies well. Its stock all around with protaper bars only. I want to have it running like my friends cr125 popping Wheelies in every Gear. Need help with upgrades

Wanna trade? Mine has too much

Have you check your power valve? A powervalve(s) broken and stuck closed will eliminate all mid range - top end power

Pipe, Reeds, and Jetting

FmF expansion chambers can be had on ebay in good shape all the time and Boyesen reeds are great and fairly inexpensive and after jetting you'll love the change!

Being an E series, the first thing you should check is the KIPS valves.

Yeah, I'm willing to bet that the KIPS system is barely working at best. Search around on here for more info but it's easy to check by taking off the pipe and looking through the exhaust port while working the KIPS by hand. Once that's sorted out there's a lot of additional power available with the right mods. I think you'll be happy with the KDX once you get it set up.

1) measure your engines squish clearance and lathe down the head to bring the squish velocity within the 10-15 m/s range. Register at the Torqsoft site to use their squish velocity calculator. (http://www.torqsoft.net/register.php)
2) Install an iridium spark plug (NGK BR8EIX) and gap it to .032" (.8mm)
3) remove the sound dampening layer inside the stock pipe or replace it with an aftermarket pipe (I prefer Pro Circuit)
4) make sure you have good compression (and replace the rings if you don't) and then jet your carb to perfection.
5) replace your low performance stock CDI with an adjustable performance CDI.
6) clean out the stock silencer

just slap a 57 teeth rear sprocket on there and call it a day

(though im convinced fixing the powervalve will have the same result

How about all the basics? Top end good, or tired? As mentioned, KIPS working properly? Reeds good? Jetting in the ballpark?

No reason modifying until you are sure you have a good running bike to start from.

Good point. In my experience, most every 2-stroke dirt bike that I've ever bought has needed a new top end right out of the gate. Granted, I usually buy cheap bikes but a fresh top end is always a great thing to have. Modifying a worn out motor in the quest for power wouldn't work out so well.

Definitely make sure all is right before even considering modifications. While the KDX is no powerhouse, it has more than enough for most, and should have no trouble at all keeping up with your average 125. If you're having difficulty getting the front wheel up, something is wrong.

I rode the bike for about 5-6 hrs straight n i ran it hard starts first kick no matter what idles all day its mint i just feel like its not as peppy as a cr/kx i want more throtle response in high gears n i really dont like that my friends.89 Cr125r with pipes kills my 200 2stroke. I want to be ahead of that bike

I agree there is some issues preventing you from realizing the bikes full potential. I have ridden my son's KDX200 in intermediate enduros and hare scrambles with no issues passing 450's. The bike is awesome. It's no MX, but on the trails you (given same ability) should lay waste to 125s.


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roody23 wrote:I rode the bike for about 5-6 hrs straight n i ran it hard starts first kick no matter what idles all day its mint i just feel like its not as peppy as a cr/kx i want more throtle response in high gears n i really dont like that my friends.89 Cr125r with pipes kills my 200 2stroke. I want to be ahead of that bike

have you tried swapping ?

put your buddy on the KDX and have you ride the 125 and see if it is still faster
if it is, look at the bike, if it is not, look at the rider

My 99 kx125 I had would kill my 90 kdx200 the 200 would win off the line no problem but the 125 had so much top end power it would smoke the DX

Probably the 5th time it's been said, check the power valves.

+1. ^