I have a 2002 Yamaha Kodiak 4x4 400. A few week ago it ran fine, a week or two later went to run it and every time I gave it gas it wanted to stall out. This is what I have done so far. Replaced carb with new, new air filter, new spark plug, pulled shout off valve, checked both filters and tank for junk, nothing found. Also fresh gas. It does the same as the old carb, as soon you give it gas it wants to die. Have no idea what the problem is. Thanks in advance.

 

Sounds to lean, just because carb is new it still needs to be adjusted to match engine. Is airbox stock? Any holes added or airleaks? Any type of air leak in the manifold will cause a lean condition. Use a can of wd40 and spray around intake manifold while running, if speed changes you have a leak. Adding holes to an airbox requires changes to carb jetting and so does exhaust modifications.

 

Thank you. Air box is stock. There is really no adjustment to carb all jets are in bowl, it is too tight to get in with it on. Have not tried wd40 but sounds good. I haven’t heard anything that could tell me about an air leak, but will try. Thanks again will let you know what happens.

 

Their should be adjustment screws on side of carb both old and new.. If their are no screws then you will never be able to tune it..

 

The only carbs I've seen with no adjustments were on small engines like lawn mowers.

 

Even if there would be no screws there are still slide adjustments, needle adjustments, float adjustments, jet sizes both main and idle, and other things that need to be set to match it to a particular engine.

 

What's the spark plug look like?

 

 

What did the spark plug tip look like? A spark plug can tell a lot about what's going on in an engine. Just saying it looked "fine" tells us nothing.

 

I looked up your carb and it does have a mixture adjustment but if you bought a new carb there is probably a plug covering the mixture screw. If your OE carb has never been rebuilt then it also probably has a plug covering the mixture screw. The mixture screw is on the bottom toward the engine side of the carb. Many ATVs are hard to reach when trying to adjust the mixture. I have a special tool to adjust the carbs on ATVs.

Did you buy an OE carb or did you buy a cheap Chinese carb? The Chinese carbs can work but I always recommend rebuilding the OE carb if at all possible before buying a replacement. From what I saw when I looked it up, the replacement OE carbs should be around $160 or so. A carb kit is usually around $20-30. The Chinese carbs usually give mixed results. Many work fine. Some don't work at all.