That's interesting. I you're having a problen with a one main jet being too lean while the next step-up is too rich, you can go down or up in partial increments by changing the MAJ (main air jet). A smaller MAJ will richen the mixture while the larger sizes will make it more lean. My TMR-MJN34 came with two additional MAJsizes for that very purpose.

That would be something to look into ifdfferent sizes MAJ's are readily availablefor the TM-33. One size up and one size down from what you have installed would be a good place to start. If thatdoesn't fix it,I guess that means thatthe 34mm barrel isn't the right sizeto accomodate theintake pulsecreated bya 331 or 340cc jug.

 

Hey Tremor, where were you 2 weeks ago? What was weird was that a richer main jet only made a bog at 3/4 throttle - ride through that and all was well. I went as rich as a 147.5 main jet before the top-end started to drop off, but I just couldn't take that bog. I'm thinking thatproblem was with the needle taper,because the bog came in right at the transition from the needle to the main jet. Unfortunately, I couldn't find a different needle for the TM-33.

Mooredan, the TM-36 is working well so far. I got my baseline jetting from the web, where those guys were using the carb on XR400's. It turned out to be a shade rich for my 340. Oddly enough, the stock jetting of the carb is right on at my elevation. I'm now running a 130 main jet, 12.5 pilot jet, clip on the needle in the 3rd slot from the top.

Right now, the bottom endsnap is a little soft compared to the TM-33, but midrange and top-end power are excellent. The accelerator pump doesn't come in until nearly 1/4 throttle, but it's starting and ending points are adjustable (just by turning a screw). So next I'll be adjusting it to come in earlier. So far though, the TM-36 is a dream to work on and I'm very satisfied with it.

 

Ill bet this can be made to work well with our stock bikes. All the higher performance 250s use at least a 37 mm carb, and the Honda uses a 40 (although it is universally accepted that this is WAY too big, and causes some off idle to midrange flatspots). I know they use more airflow by slightly larger/more valves, and much larger cams, but in the big picture, the 36 with a good exhaust, filter, and proper jetting should be perfect. Im going to buy it this winter, and see how it goes.Spring will see!!

 

A while back someone posted a pic of a D-Tracker and it was running an FCR39 in it.

 

The KX250F has a FCR37 on it

 

Oh, I see. I misinterpreted the condition as a WOT problem. I have heard of people going to a different needle on the TM-33 to remedy the lack of top-end pull, but I'm not sure if it was for the specific problem you are having.

Glad to hear the 36 is working for you. I don't think you'll completely recoup your low-end from listening to others who own it, but I think you will like it better over-all.

 

Here's a tuning update. On Saturday, I installed a new plug to do a plug check with my current jetting: 130 main jet, 12.5 pilot jet, clip on needle in 3rd slot, air/fuel screw 2 turns out, airbox lid off.I didn't do a plug chop, but I put about 10 miles on in a variety of conditions. The plug was a light to medium brown - good enough for me. I wasn't experiencing any jetting issues (except for some minor decel popping), but the bottom-end felt sort of soft compared to the TM33. The bike was a rocket in the midrange and top-end though.

The Mikuni tuning manual for the carb says that the accelerator pump should come in at about 1/4 throttle and shut off at 2/3 throttle. The accelerator pump on the TM33 came in right off idle, so I setthis oneto start there as well. I idled around in 2nd gear and then whacked the throttle open - a huge bog followed by a 2-stroke-like hit! That was fun, but not what I wanted. I started backing off the accelerator pump 1 turn at a time, to make it come it later. Each turn, the bog got less and the bottom-end power felt stronger. I eliminated the bog with the accelerator pump coming in at about 1/8 throttle.Once the bog was gone, bottom-end felt just as strong as the TM-33 (at least to my untrained butt). The difference is that midrange ismuch stronger now, so the bike just flat-out pulls! Next, I played with when the accelerator pump shuts off. Best throttle response was acheived when the accelerator pump stopped pumping at 3/4 throttle. Any later than that caused a rich condition.

So there you have it. I've got the carb jetted right now, and the bike runs better than ever. Time to put some miles on...

 

Good post, before I had my tank snafu thats just about what mine was doing, when I get my new tank that's where all start.

Kevin

 

Remember that the throttle wheel of the TM-36 will hit the Clarke tank. You have to do a bit of grinding off the top of the wheel to get it to clear. I ground mine down to 1/16"above the throttle spring pegs. You don't use the top part of the throttle wheel anyway (except to anchor the throttle spring), so it's not a big deal. The stock throttle wheel is available separately (I checked before I started grinding ), so if you do mess it up, all is not lost.

 

Found some info on the TM36-68 here:
http://www.motorcyclecarbs.com/Mikun...30223185115991