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TM31 on KLX250s

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I have scoured GOOGLE and SEARCHED through threads. Will a TM31 (DR250 "dirt model pumper") fit on a 2007 KLX250s? When I mean fit, I mean "run proper or correctly".

The most info I have found,so far,was that it's actually a 31.8x almost a 32 basically. Could it sent it off to be made into a 32plus?

I am looking to keep the stock 250 jug on there for the time being and do the sproket,intake and exhaust mods.The bike will be mostly ridden on trails and around town. Probably no serious highway use for the time being. (being a 250)

The carb is going to be coming with the throttle,cables,intake boots etc...from the 90' DR250.

Looking for "snap" throttle throughout the powerband,250 wise.

The carb was a good deal considering what I would of spent on jet kit etc..

Thoughts, concerns, considerations?


EDIT: Elevation..ahhh forgot, I Live in Denver,~MILE HIGH~ because the air is thinner up here what would be the effects on running a smaller carb?

Less air = less fuel to be run in a carb.Meaning to me,No need for a TM33 at this alti to get the same effect as needing a bigger carb down south. OR, does this mean I am needing a BIGGER carb to make up for the lose of air.

again,not looking for great gains,just "snap" in throttle response,considering the stock CVK uses vacuum,air,for accelleration,correct?

dumb dumb..

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You would loose about 14% air flow with the TM31. At higher altitudes, you want to get as much air as possible through the carb to compensate for the thinner air. As a rough estimate, you loose 10% of your power for each 3,000 ft of elevation increase.

For better throttle response why not install a Dynojet carb kit? That and opening the intake and exhaust should give positive results. The jetting issues have already been worked out for the stock CVK and 33 and 36mm Mikunis.

Ride on


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Thanks for the response. I should of known better and had it "reversed" in my mind for some reason. Perhaps it was because I thought since it came off of a 250 and is a pumper it would fit perfect on this 250. It has been a Loooong time since I have had a bike, let alone, Do any sort of MODS. This bike is just lacking a little in the power dept,for me. As far as throttle response and a wee bit down on the power side. Coming from an R1, Banshee and 660 Raptor, years ago, I never reallty felt the need to change from stock. (They were ALL carb'd) The last high performance vech. I owned was a 600hp Subaru Sti. The forced induction was explained and researched by me. A boosted motor pulls in air but in this alti,it still actually runs around ( + - )2lbs less on the boost because of the thin air,even though the engine management doesn't really detect it, it therefore runs a little on the rich side and less likely of the accurance of running into detonation.

I will try the rejet first then,maybe I will like that enough. If not,then I will hunt around for a TM36 or FCR35, that way, down the road If I want to go BIG BORE, I will be on the right track.

I REALLY like the fact this bike is pretty "flickable" in the dirt :thumbsup:


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