Hey all, I just picked up a 1993 Yamaha Big Bear 350 that had been sitting for a while. I'm a first time ATV owner and am having trouble getting it to idle and run smoothly.

I won the machine in a government surplus auction back in November and it has very few hours on it for it's age. I was only able to pick it up last weekend and I think it had been sitting for quite a while before it went up for auction.

The fuel that was in it was very stale, so we drained the tank and ran some Seafoam fuel treatment through the carb. We've checked the air filter, which was soaked in old gas and I have a new filter for it. The carb has been taken apart and cleaned out.

The problem is it will only run with full choke, and even then it runs very rough and bogs and stalls when you give it throttle. If you can get it revved up it runs and drives but it's still very rough.

So what should my next trouble shooting steps be?

 

I would recommend buying a carb rebuild kit, pull the carb off, and rebuild it. This is very common to carbs that have sat for a long time. The fact that it runs a little better when you choke it out tells me further that the carb needs to be rebuilt. If you do this, most likely you'll be amazed at how well it runs after you do this. I've done this many, many times on everything from quads to jetskis.

 

Thanks, I will give that a shot

 

Always instal a carb/rebuild kit on any machine that's been sitting up.. Not worth just trying to clean one and having to go back in later on. Carb kits are cheap.Here's just one example,may find some even cheaper.http://www.ebay.com/itm/Yamaha-Big-Bear-350-YFM350FW-Carburetor-89-97-Carb-Rebuild-Kit-Repair-YFM350-FW-/171375802307?pt=Motors_ATV_Parts_Accessories&hash=item27e6cb37c3&vxp=mtr

 

Not sure if you've rebuilt a carb before or not so sorry if you already know this. Take the carb apart and use carb cleaner on all the little holes, ports, etc. Scrape all corrosion off as well. You want that thing clean clean clean. It takes time to do that but it's worth it in the end when you know that carb is clean and not contributing to the problem (if any problem still exists after rebuilding).

I always use the stock metal parts that come in the carb and just clean them. I replace all rubber though with the new stuff.

Hope this helps,

-Alli

 

Really if you're looking for a product specifically for cleaning the fuel system you want to use Chevron Techron. Just be wary of any product that makes a laundry list of claims. In general, if a product makes lots of claims, they rarely perform any one of those claims well.

This was out of your control obviously since you purchased an ATV that was already sitting, but moving forward make sure to use a high quality fuel stabilizer/ethanol treatment. I would be happy to send out a couple samples of our STA-BILŽ 360° Powersports product for you to try.

Please let me know if you have any further questions/comments.

Have a great day!