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2010 KlX 250S TM33/34 pumper problem

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Hello

First post and very new to this site.

I recently purchased a bill blue tm33 pumper carb and I am having issues

Bogging out whenever the pumper is used. I can slowly advance the throttle and everything seems to work okay. When I give it a full throttle she blogs, hesitates and eventually stalls.

Bill set it up with a 140 main and a

40 pilot. The fuel screw is 1.5 turns out. My elevation is 650 feet and I am currently running a power core 4 exhaust with a power bomb header.

Do you see anything I could change to help improve the proformance?

I have called bill several times and I think I am starting to become a thorn in his side. I figured I would try this route before I bother him again.

Thank you for you time :)

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That's a pretty common carb upgrade on that bike, there should be a lot of jetting advice on here for your setup.

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Sorry to hear you are having problems getting advice from Bill. I have had good luck getting information out of him. What advice has he given you to correct the problem ? 

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I have nothing against bill. He is a great guy. I do not have much mechanical experience and I don't want to be a bother.

I was missing a spring behind the Excelerator pump piston. I was told to use a spring from a ball point pen.

It fit well but I was not getting very much fuel out of the pump. Turns out

The spring I had in there was blocking the fuel.

I called bill again and he said to go to a 42 pilot and a 142.5 main.

The local shop didn't have a 42 pilot so I tried a 45 and still got the bog. I went to the shop again and this time got a 35 pilot. I have not tried it yet...that is tomorrow's task.

I pulled the spark plug and it looked pretty good.

Would the bog be from to much fuel or not enough? I'm stumped.

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I put the 35 pilot in and got the same bog. I opened the old CV carb out of curiosity and found that the old carb has a 122.5 an a 35 pilot.

Could this be the problem? And if so where should I start? The tm33 currently has a 140 main

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What I would do is get the carb fixed and jetted as per recommendation. Get the right spring on the pumper assembly and make sure it is in good working order. You cannot really diagnose issues until you have established a baseline from which to work. I think your problem is in the pumper adjustment. It has to deliver the right amount of fuel at the right time in the throttle twist, and for the proper duration.  Do not get hung up on the fact that one carb has different size main jets vs. another for the same application. You are comparing apples and oranges. Once you get it all set up per recommendation, ride it. I am going to guess it will probably still bog. Because I do not have a dyno  in my garage I would take the pumper circuit out of the mix and make sure that the idle mixture, the needle setting, and the main jet are right.  Look at your plug and when you get a nice light tan insulator those jets circuits are right. Did this make a difference in how the pumper portion of the fuel circuit functioned ? I do not know how Mikuni carbs are adjusted for timing duration and flow. I am assuming you do since you have one in your hand and have made some attempts to do so. Hopefully this gets you started and keep the posts coming as to your progress.

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