I have a big bear 400 a 2004 I just put a new carb on it and the old one done it to but I can get it to idle good and then when I put it in gear it will slowly die but if I get it adjusted were it will idle in gear and I put it in neutral give it some throttle it will not idle back down were it need to be is the first prob

2 one is when I'm going down the road and open it wide open seems like it startes lousing power and gain power and bogs but 3/4 is fine and as long as the rooms are low mid rising is fine to just a high rev it has probe

 

Spray some wd40 around the intake manifold,base and head gasket and see if the engine rpms change or if it seems to run right for a bit. If it does,could be an air leak.

 

ok I will try that tomorrow if the idle does change what do I do next

 

Just do one section at a time. Around the intake manifold first and see if any change. If it does,could be needing an new intake manifold or gasket if so equipped. If engine rpms don't change,spray around the base gasket,check,then the head gasket. Plus simple things like making sure valve clearance is set correctly,air filter ok,new plug,fresh fuel. Don't know if it has a fuel pump or gravity,but either way make sure you're getting good fuel flow to the carb. Some of these Chinese after market carbs are hit or miss also,jetting may not be the same as the oem carb. I'd check that also even though you said it ran the same with either carb.

 

 

A lot easier to adjust the old style than the bucket shim system. Have at tdc,check clearance. If they're tight or loose, loosen the 10mm lock nut,turn the adjuster in or out,check clearance again,tighten the lock nut. There are special tools for this but not necessary.Wrench,needle nose pliers to keep the adjuster from moving when you tighten the lock nut. May take a couple tries to get into spec. Several videos on youtube that can help also. Here's one on a later model Big Bear.