I am new to the group. I have a 2003 yamaha kodaik 400 not 450 4x4 just upgraded to EPI clutch and belt added 27 inch tires . The Bike cranks idles great goes into gear and drives fine, however under load climbing small inclines hills or mud and sand the bike boggs down and sputters. The clutch was added to hoepfully increase low end power and i am sure it does but apparently i have another problem. I checked all the vent hoses all clear, new spark plug. no smoke except under heavy load a bit of smoke. In reverse i know there is limter but not sure why issue in forward. I had the bike completely down to frame changed all the fenders out thats when i checked all the vent lines.
Could this be as simple as a carb problem? I have had the carb off and cleaned. i did have a problem with leaking gas i think it was the float that seems to be o.k. now please advise i will try anything.. i do have a servce manual thanks in advance