hey fellow cat lovers. I"ve got a 98 454 with enough power to pull down a trailer house, but I seem to be having some trouble you might be able to help me with. Seems like about half throttle she starts banging out. Its definatly electrical and the only thing I"ve diagnosed is that the voltage at the battery is 13.8 at idle and it goes down as you increse throttle. Will a voltage drop cause this problem?

 

A BIG drop in voltage will cause this. What is your voltage dropping to at mid-throttle?

 

all i can get to is mid throttle an the voltageis at 12.6-13.0 when she starts backfireing, right at mid throttle

 

I don't think that is a big enough drop to cause that. You are on the low end but there is still enogh voltage to run. Are you sure you carb is clean? the needle and seat could be clogged/sticking and not allowing enough fuel in the bowl or you could have some trash in a jet.

 

Yes thats what I thought because I've run other four wheelers with the regulator totaly out and just put a car battery on the rack, but this thing is eating my lunch, I've done went through the carb and all jets seem to be clean. With the breather tube off you can see gas spitting back out of the carb when she backfires thats why I thought it was my spark breaking down. The manual says it could be timing or week valve springs also but I just don't see how that could happen over night. Im going to pull the gas tank and check to see if the cut off valve might be restricted but that seems like it would have to little gas insted of to much. I'm ready to ride so if I cant figure this out I'll prabably put the thing back together today and run some seafoam through it to see if I can break something free. Any help is appresiated

 

check for a broke valve spring,