2008 rmz 250 stumbling at the bottom end

Hello, I have an 08 rmz 250. Im having a problem with a lowend, there's a good hesitation when a just barely open the throttle, if I hold it in this position it does not clear up and sometime it will stall. if I stay out of this erea it runs good everywhere else except for the rmz's fading top end.

I've cleaned the entire carb and jets, and did the O ring mod, still had the stumble.

The bike is completely stock with stock jetting

mian jet 162

pilot jet 42

leak jet 40

starter jet 75

The fuel screw is at 1 1/2 out

I live and ride at 5000 ft in northeastern Nevada. It's cold rite now, but very dry and hot in the summer. I wanted to ask your advise before messing with things too much when I could get some solid advise first. Thanks for any help

Edited by jeff z

alwsy been this way since new or just started happening?

there was always a hesitation at the bottom and it was a problem sometimes in the corners, but now the temps are in the 45 to 50 range and its much worse. When I first start it with the choke on its not there, if that helps at all. Thanks again

does it get better or worse with heat?

it worked better in the heat

Dude I have a 2008 rmz250 as well and it has gotten colder here. Bike runs like crap below 60 degrees. Popping and hesitation on the lowend and got better as it warmed up, not great though. I went from a 42 to a 45 pilot and it works awesome now. I also just did the o-ring mod and it eliminated some of the bog I had.

You may want to try going out a bit more on the fuel screw first. 1.5 out is stock but you may be able to eliminate the issue with 2 or 2.5 turns out. If it doesn't clear up, go with the 45 pilot.

you sure it came stock with a 40 leak jet?

Yes I brought it new. There's one thing I forgot to mention is that I went with a 2 stroke filter cage and a anti backfire twin air filter. I bought it last year when it was the same temperature and it did not have this problem as bad. that was when it had the backfire screen. Is the leak jet too small?

I took stavendirtbikes advise today and went out a half a turn on the fuel screw, and it took care of about 3/4 of the problem, and when the bikeshop opens I was going to try going up on the pilot. Thanks for the reply Eddie and stavendirtbike for the replies. Any more help Eddie would be great thanks.

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