2000 Yamaha Bear Tracker 250 Won't Run WoT
 

Hopefully this is the right forum...
I just bought a Bear Tracker 250 that looks like it led a hard life.
When I first tried to start it, it would only run with the choke on, and bog/stutter at WoT. I took apart the carb (34 Mikuni, vacuum) and cleaned everything and put it back together and back on the ATV.

Now it runs great at idle.

Now when I try to accelerate in gear, it just bogs back to idle and seems to shutter like it is fuel starving or something.

When I was in the carb, both diaphrams looked good and I didn't see much varnishing. The pilot jet was partially blocked and I cleaned that with a wire.
I have checked the spark plug (gap .025) and the air filter (now removed) and not sure where else to look.

Any help would be appreciated.

Thanks,
Joe

2000 Yamaha Bear Tracker 250 Won't Run WoT
 

where you running it without the air filter.......if not check for vacum leaks

2000 Yamaha Bear Tracker 250 Won't Run WoT
 

I ran it with a very dirty filter/pre-filter and without.
It ran the same both ways.
The vacuum operated slide seem to operate fine as I looked at in (in neutral).
It is at a bike shop now.
I guess it will run right in a few days...

Thanks,
Joe

2000 Yamaha Bear Tracker 250 Won't Run WoT
 

After 40 days in the shop, still won't run WoT. The tech told me he went throught the carb, fuel delivery, new air filter, plug, etc. But didn't have a like atv to swap parts with.
While moving it out of my garage to the shed, I forgot the choke on and it ran great up and down the street. It just wouldn't idle.
I pushed the choke in and it idled great, just falls on its face at WoT.
Any ideas would be great.
Thanks,
Joe

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I Have the same machine with the exact same problem, I have noticed weak spark is yours? Mine is still not running, Idles fine if you gap it it bogs down and coughs.... let off runns fine.

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No, I haven't noticed a weak spark. Did you try to run yours with the choke on, after it is warmed up? If your spark is weak, it may be the ignition.
Since mine runs great (warmed up) with the choke on, I'm guessing my ignition is ok.
Thanks,
Joe

try running it at wot when it dies shut fuel off at the tank then open the screw on the botem of the bowel of carb if it dont leak fuel then it is your float or needel and seat mine did the same thing and i overlooked the neadelseat i removed it and it had a screan above it that was partly cloged cleaned out the fuel port and it runs great