I have a 1988 Warrior with an hmf exhaust, k&n air filter and bored over one. Just purchased a Mikuni carb, not stock, for it that is supposed to fit all years The problem I'am having now is it's just not running right. It has a 240 main jet in it and the needle is set all the way to the lean side and the air screw is out 3 turns. It spits and sputters and backfires and has no power. The spark plug is still a little black and a little smoke out the tail pipe. I've also tried other jets in it all the way down to a 170 and it does the same thing. Can someone help, I'am out of ideas and want to go riding!!!

 

Nobody knows anything about Mikuni carb on this site? I guess everybody is out riding.

 

Are you talking about the 36mm aftermarket replacement roundslide Mikuni? It should have run pretty good right out of the box,if it sputters and runs rich, the float may need to be reset, no matter what jet size you have, if the bowl is too full, you will pull excess gas into the intake and run rich, which causes the sputters. Put it back to the way it came out of the box to start with, make sure the float height is correct, and the needle and seat is sealing up good, so it maintains the bowl at the right level. one way to check with the carb on the motor and full of gas, put a short clear hose on the drain, lift it up along side the carb and open the drain screw. The gas should rise in the tube to the level of the bowl, this will tell you if it is too high or low. If it lines up or goes over the seam where the bowl is fastened to the carb, you are way too high, and will suck gas in, no matte how small of a jet or where your needle is set.

 

this is a dumb question, but in all this rebuilding, did you check your parking brake wire?....if it idles correctly but won't go past idle, maybe thats it?....idk just a thought as they are electronically controlled still....

 

Very good point, you did not mention if it idled good, and lost power and sputtered just off idle, if that is so, then the parking brake switch could be a very good place to start

 

sounds like a fouled plug, or bad valves to me.

 

i know mine was sputtering and loosing power when my parking brake wire was loose and messed up.......soon as i fixed it it ran like "new" again......it did it at idle if the choke was pulled in and it was trying to idle above the electronic management