I recently picked up a 2001 Bog Bear 2wd for $400. It has a few issues but basically ran pretty good. The carb had a lot of water in it at one time and I replaced it with a Ebay model for $60. I never ran it that much on the road with working on the brakes and such.


Anyway new carb on fires up runs nice. put on the filter and filter box cover and it misses out when revving it up. Starts missing about mid range through high range. Runs great with the filter on but the filter box cover off.


I'm thinking that is a rich condition but not sure how to fix it. No adjustments on the outside. Only thing to try is to lower the needle. The air intake that slips in near the back of the tank looks smallish but is
oem.


Am I missing something simple?


Thanks,
Rob

 

Check that something hasn't made a nest in the air pipe. We had a Honda that came in running badly and found the entire air box full of nuts. Turned out the bike was parked near the owners bird table and some enterprising rodent had decided to store the contents of the table in the air box. Must have taken several days worth of bird feed, the quantity we got out.
Even in water the alloy body and brass jets survive quite well. I always clean and re-fit the original carb, that way you know the jets are the right size and adjusters are set right. I didn't think you could lower the needle on the big bear carb but, if you can, it may be worth moving it down a notch and seeing how it runs. The colour of the plug nose will tell you if it is running weak or rich.

 

thanks for the reply. the box and intake is clean. on the oem carb it looks like you can adjust the needle a bit. I haven't looked at the new carb. It was only $60 so I figured what the heck. I bought a little 250 Bruin and someone had put a new off brand carb on it and it runs great.


I'll get some time on it tonight and see if I can figure it out.

 

Update the problem was a cheap china $60 carb I bought off ebay. it looked really nice, exact copy. maybe some junk in it, maybe not the exact spec for my atv(I fiddled with the main needle and nothing made a difference).


I found a NIB oem carb for about $160 on ebay and jumped on it. Runs perfect now.


Sometimes that stuff works, sometimes not.