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Mikuni TM40 questions

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03 xr400 - 130/15 jetting, mixture screw was 3 turns out and popping on decel after removing snorkel and installing Uni filter. CHM exhaust. Went to 3.5 turns out and it burbles mildly on decel, but no popping or backfire.

I ordered 132.5 and 135 main jets.

Leave it alone or would it be better with a bigger jet and less turns out on the mix screw?

2) 'choke' stays when pulled all the way out (cold start), but when I try to move it in to 1/2 way closed or less the plunger gets sucked down to the carb and I have to manually hold it out or the bike will die. ?????

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Do they not have motorcycle dealers in Indiana? Any dealer should have Mikuni jets without you having to special order them.

Try a 17.5 pilot and retune the fuel screw.

Why did you order the larger mains?

What's your elevation?

As far as I know, there are not 2 positions on the choke plunger. Choke is either on or off.

Edited by Trailryder42

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Do they not have motorcycle dealers in Indiana? Any dealer should have Mikuni jets without you having to special order them.

Try a 17.5 pilot and retune the fuel screw.

Why did you order the larger mains?

What's your elevation?

As far as I know, there are not 2 positions on the choke plunger. Choke is either on or off.

Guess again. Dealers do not stock those, nor many jets at all. wasn't special order. I always mail order over local stealer.

Elevation is 700'

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