How will the TM36-68 work with the stock 250cc and a big gun Evo R until I go with a big bore? Might just try the pumper first and see if it picks up enough spunk to keep me happy in the trails for awhile longer. I don't want to buy a carb now and then another when I swap the jug

 

To big of a carb for stock bore.

 

You don't think you would find a buyer here for the tm33 when you step up to the tm36-38?

 

I know of a few guys who've put TM-36's on with a stock bore. Some have gotten away with simply slapping the carb on with the stock jetting, while others had to back down the main and pilot jet 1 step. That all depends on your elevation. No matter what though, you'll need a good aftermarket air filter and remove the airbox lid. You've already got a full exhaust, so that should be all you need to do.

As for the TM-36 being too big for the stock bore, it probably is. Your low end power and throttle response will likely suffer due to the lack of vacuum signal. But if all you have is the stock CV carb to compare it to, you'll be happy anyway.

 

It would stay piled up where it was removed. I know my weakness, and selling stuff I am done with is one of them.

 

Well, it's an old thread but I thought I'd post a "log entry" on my efforts to put a TM36 on a stock bore KLX250.

It works like charm. I've had completely re-jetted stock CV, a TM33 and now aTM36. Each carb has been jetted by doing real-world riding testing with an LM-2 A/F meter hooked up.
Of all the carbs (and air box experiments) the TM36 + stock 250 snorkel works the best so far. Not a hint of bad throttle response or any sort of hesitation.

When properly jetted the TM36 is not one darn bit "too big" for stock bore 250.

My jetting at this point:
PJ = 15, stock pilot AJ
9EBY01-50 needle in the middle slot.
P-4 needle jet
118 main jet.
(edit on the MJ size. I have a handful of 118 jets but not a single 116. The stamped numbers are not very clear, what looked like "116" is most likely a 118.)

The bike runs really well but I want to optimize it bit further.

A/F at idle is 13 - 14 when engine is really hot, but with "luke warm" engine the idle A/F is more like 14 - 14.5.
At very small throttle opening (up to less than 1/4) the A/F hovers between 14 -15. That works good and gives very good fuel economy but I'm going to try a one size smaller pilot air jet to richen the idle and "just above idle" a little bit.

At mid throttle I'm around 13 and at WOT & full RPM about 12.

I will at some point try one size smaller MJ to try to bring the WOT A/F to 12 -13.

But the rest of the optimization is just search for perfection. With the current jetting there's no stuttering, no hesitation, solid reliable idle and very nice throttle response. It's just that with the A/F meter one can actually see that I'm still little off from jetting perfection.
Seat-of-the-pants jetting is already as good as one could ever hope for.

--
Mikko

 

Yeah, there's a few guys who've used those carbs on stock bores with no problems. I wish I would have gone with that instead of the TM33 just because it fits better and you can use both cables. If it's a little too much carb, use a UNI air filter, KDX snorkel, and some kind of free-breathening pipe. Ditching the CVK and going to a different carb makes a huge difference on the trail. On the pavement, it's all the same.

 

I agree.... I’m still running stock bore on mine with the TM36-68 and it’s great.... I won’t go back to the CVK.

Wish I had an A/F meter though when I was tuning it in but I am pretty sure my jetting is good....

FlyingFinn... What’s your altitude???? My jetting is quite a bit richer than yours.

 

I'm at sea level. But remember that I have the stock snorkel on, it makes a big difference in the jetting at > 1/2 throttle.

--
Mikko

 

That’s interesting on your jetting.... I am also at sea level and have a completely open air box + FMF pipe and my jetting is much richer....

I have

7 pilot jet, stock pump nozzle
Same needle and needle position as you
P-6 needle jet
130 main

My main might sound a smidge to big but I have tried a 125 and 127.5 and it didn’t pull as well as it does with the 130.

I have been riding with this carb now for about 6 months with no problems.