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View Full Version : Big Bear running like crap, help please?



RedRider_AK
11-13-2007, 06:24 PM
It's wintertime now, and I've been using my Big Bear recently. I think the jetting is messed up on it, or something, because suddenly she doesn't like to idle very much. By which I mean at all.

Anyway, here's the rundown on what the machine looks like and how it acts.

- This summer, took out stock main jet and replaced it with the "modified intake and exhaust" jet from my Dynojet kit, to richen it up a tad. You know, just for protection. I heard stock and DJ numbers are different, so numbers probably won't help much, but I think stock was a 92.5 and the Dynojet I put in was a 96 or so. Anyway, it ran just great all summer, whoop-dee-doo. Didn't want to stall out or anything.

- Now starting a few weeks ago, when temperatures got colder, it all of a sudden dies every damn time I let off the gas! Literally, if I let off the gas to go into a corner, or downshift, or stop at an intersection, it's constantly wanting to die. And when you give it some gas, it'll keep revving for a few seconds after you let off the gas, and then start wanting to die again. It got really bad as I was going through a snowy trail this morning, so I stopped and revved the engine in neutral a little bit. Every time I would let it get close to dying, then revved it up, a cloud of black smoke would come out the exhaust.

- I always thought black smoke was it running too rich, but it's wintertime now... shouldn't it be running leaner? I am very confused. I didn't mess with the pilot jet or the needle clip at all, nor did I fiddle with the air-fuel screw. It just seems to have started dying out of nowhere.

There's always something new going wrong with this pile, and it's barely a year old! I'm seriously considering restoring it to factory condition and selling it, then using the money to build up a NICE TRX250R or something.

Thanks guys!

MTS
11-13-2007, 09:35 PM
Choke Slide isnt hanging up in the carb?? or the cable possibly? for starters. Maby dump some gas line anti-freeze in the tank too...water dose funny things to small motors... when it gets cold

RedRider_AK
11-14-2007, 02:03 AM
Choke Slide isnt hanging up in the carb?? or the cable possibly? for starters. Maby dump some gas line anti-freeze in the tank too...water dose funny things to small motors... when it gets cold

No, the choke works fine. It starts up first pull with half choke, and then idles high with the choke on. Then after idling for a little bit, I turn the choke off and it works normally, but then after it thoroughly heats up (riding for 5 minutes) it doesn't like to idle at all.

I've already done the Iso-Heet stuff, it didn't help or hurt.

I'll try putting on a new air filter (crappy paper :( ) and sticking the old main jet in. Hopefully that'll help.