...Yup, better than the stock carb, actually. When I put on my 340 kit, I also got a 34mm Mikuni TM33 pumper carb from Bill Blue. I don't know why, but I could never get that carb jetted right with the lid off of my airbox. With the airbox lid on, a 42.5 pilot and a 142.5 main jet, the bike ran great, but there was a noticeable improvement in the bottomto midrangepowerwith the airbox lid off.With the lid off though, the main jet was giving me problems. With the 142.5 main jet, it was way lean above 3/4 throttle, and would surge badly up to 8,000 RPM, where it would sign off altogether. If I bumped up to a larger main jet, I'd get a big bog around 3/4 throttle.

I figured that since I've come this far, there no sense in giving away power now, so I ordered a Mikuni TM36-68 pumper carb from Carb Parts Warehouse. The TM36 doesn't need adapters front or rear to fit the KLX, and it is the same height as the stock carb. It's 1/4" shorter front to rear than the TM34 from Bill Blue, so it literally falls into place, but there's still enough rubber over the spigots to seal up well.



The TM36 is on the left, while the TM34 is on the right. Since the TM36 is an aftermarket-only carb, everything on it is adjustable. You can adjust throttle spring tension, accelerator pump start and stop positions, and the air/fuel mixture screw can be adjusted by finger tip. The big nut on the bottom covers the main jet. You can change main jets simply by rotating the carb in the bike and removing the nut.



Right out of the box, the carb fits well and can be used with the stock tank with no problem (I checked). With the Clarke tank though, the top of the throttle wheel hits the tank. The throttle cable bracket could bebent a little so that the cable flows over the head better, but it will work as-is.




After somegrindingoff the top of the throttle wheel, even the Clarke tank works. Nothing else needs to be modified.




It's actually even easier to get to the idle adjuster too. The TM-36 uses the same style jets as the TM34, but much smaller sizes for some reason. I'm now running a 15 pilot jet, a 130 main jet (compared to a 42.5 and a 142.5), and the clip on the needle in the 3rd slot from the top. Throttle response is crisp, and the bike will rev to redline without any surging or bogging whatsoever (with the airbox lid off). The low-RPM snap isabout the same asthe TM34, butmid-range and top-end power isstronger.

For 250cc's, I'm sure the TM34 would have been perfect, but at 340cc's and no airbox lid, I think I was running out of carb. The TM36 works very well for me now.

Now, my TM34 is up for sale. Before I put it on eBay, I thought I'd see if anybody here wants it. I've put about 650 miles on it, but it's still like new. I paid $342.00 for it, including the T-handle air/fuel screw, but I'll sell it for $300.00 plus shipping. I'll even jet it any way you want it. PM me if anybody is interested.

 

Good report, Mike. I had no idea that a TM 36 would fit the 250. I've seen them on the KLX 300 but there is no electric starter to get in the way. I would think that the 36 would be too much carb for the stock bore 250 though. Anybody have experience with that?

I wonder why the 34 didn't work well on your 340? I have a Bill Blue modded TM 34 and it came jetted almost perfectly, ran great and fit was fantastic? Oh well.

Have you had your 340 on a Dyno yet? I'd be curious to see some fresh numbers on some of the engine mods now that there are more out there.

Bill Dragoo
Norman Oklahoma
06 KLX 331

 

I agree that the TM36 would probably be too much carb for a stock engine. Even with the electric starter though, the carb fits just fine. Yes, it's close to the starter, but it doesn't rub or touch anywhere.

I don't know what the deal with my TM34 is either, but I know that the jets that others were using with their 331's were just too lean for me, even with the airbox lid on. I could get it jettedright with the airbox lid on, but off was a different story. It ended up being that I could have good midrange or good top-end, but not both.

There are no motorcycle dyno's in my area, otherwise I'd love to see what I've got now. I know that for the type of riding I do, the amount of power it puts out is almost perfect.

 

Great write up! I to have a 340 and thought about the 36, now assoon as I'm done writing this I'm going to by that carb. Once again thanks.

 

Thanks for posting just ordered the carb there going to jet it and send it out today. One quick question what pipe are you running, and what your elevation? I just going to copy your jetting and see how I stand. One last thing are you using the stock throttle cable, and if not what did you get?

Kevin

 

I would love to see if this carb could be "jetted down" to fit our bikes (with all the normal mods IE exhaust, filter, crankcase mod, air box lid alterations, etc) and grow with our mods?????? Just too much air, or????

 

Glad I could help! My elevation is 2,400' ASL. I'm running a K&N air filter with the lid off offthe airbox. My exhaust is kind of a one-off, with a custom head pipe and a Supertrapp IDS2 quiet core muffler. I built the head pipe toresemble a Four Stroke Works head pipe, using 1 1/2" stainless tubing. The throttle cable is from Four Stroke Works and it came with my Magura 1/4-turn throttle. The stock cable willwork as well.The difference between the two is on the throttle end, not the carb end.

The TM36-68 comes with a 12.5 pilot and a 130 main jet.I tried a 132.5 main jet and it was too rich for me. I bumped the pilot jet up to a 15, and I have my air/fuel screw at 1 3/4 turns out from closed. I also moved the clip on the needle down 1 notch from stock (3rd slot from the top). One last thing, the TM36 has an adjustable accelerator pump squirter right in the middle of the bore on the airbox side. It's adjustable in that it can be rotated to spray in different directions. Make sure it squirts right downthe center towards the engine and not at the sides. Put some fuel in the carb and open the throttle - you'll easily be able to see it squirt. To rotate the squirter,use a pair a needle-nose pliers and gently twist it - it doesn't take much.

Good luck!

 

My elevation is 650' so i'll try your settings 1st. I remember your pipe. You did a nice job. I'll let you know how it goes.

Kevin

 

Mustang,

I too have similar issues with the TM34 on my 331cc bike. ...just can't get the jetting right for running without the airbox lid and I have a flat spot around 3/4 throttle. Our bikes only have a 9cc difference and it probably doesn't matter, but do you think that this carb might work for me too?

I know it's been just a few days since your post, but how are things working out with the new carb?

 

I've got one to I'll let you know how it goes in a few days.