xr 250 mikuni tm 32 jetting?

hey i have 2001 xr 250r with a new mikuni tm 32 from xrs only i ride at around 1500-2000 feet, have a white bros slip-on, grounded out header welds removed snorkel etc. When cold if you dont start it first couple kicks it floods quickly and is impossible to start unless rollstarting. The bike also bogs more on accelaration then stock. any ideas how to solve these problems? jets in the carb at the moment are 195 main and 35 pilot spare jets i have are 200,190 main and 30,40 pilot


What does your plug looks like? I suspect you are too rich, especially on the main jet.

it was quite black when i pulled it out to clean it when it flooded. the bike revs clean from about 1/3 throttle to max rpm, i might try the leaner pilot?

Play with the fuel screw first. Get it started and warmed up as best you can, then turn the screw in. If you can seat it without any change, go to a smaller pilot. Once you can get the idle to change when truning the screw either way, you got the right pilot. Then, turn the screw in until the idle changes and then out til it changes. Count your turns, and whatever you come up with, the middle is about where you need to set your fuel screw at. And check your plug regularly.

For the main, get the pilot dialed in first, then start doing plug tests (use a new plug or a very good cleaned up one). Warm up the bike, then do a hard pull through all the gear, then shut the bike immediately. Check the plug for color. White is lean, black is rich. Try and get the lightly toasted marshmellow color. If you get brown or so, you can play with the needle height by moving the clip. Moving the clip up is leaner, down is richer.

I get what you are saying about the bogging for the first 1/3 of throttle. Mine just sputtered pretty much. I couldn't understand why I was so rich when according to the "average" set up that was sent (jetting and elevation), it seemed if anything I might would have been lean. But, with the black spark plug and running conditions it was too rich. I think realistically it was set up for a big bore. Luckily the smaller jets seem to work for me and the clip is next to last at the top. Plug is a good amber color. Being that I am using the smaller jets at 500' I would think you are going to need smaller than the ones sent to you. I am a rookie so it is just hypothetical. I did some researching on the web and lots on carb tuning info out there. It can be figured out by how the bike runs, what part of the throttle and plug. Best thing I read was, "if you have a choice, it is always good to be a little rich". Which is why I was so cautious to go with the smaller jets, but, they worked.

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