whats the deal with my quad.

[ranger400ex1994]

well i just sold my 406 motor to my buddy and he traded me the same year 2002 stock 400ex motor for my 406 motor plus some money to boot. now i put my fmf full system back on and now when i sit and rev it up the headder pipe will start to glow red. my jetting is 40plot and 155 main jet. is that to lean. thats the same jetting i had with my 406 and it did the same thing with the headder pipe. and i have a k$n air filter with some holes drilled in the air box and thats it. the headder pipe bolts are tight what else could be the problem.

[Old Head]

I run a 170 main jet with a slip on k/n without airbox lid. I have no troubles at all. not sure what the needle is cause its the one that came with the dyno jet kit. and the screw on the bottom of the carb is 3 1/2 turns out can't remeber what its called , having brain farts atm.

[cals400ex]

mainjet is just fine. if it glows at idle, turn the fuel screw out a little bit. if it glows when giving it a bit of gas, lower the needle clip one position. the glowing headers is especially bad on stainless steel headers too. lowering the clip should take care of most of the glowing though. i can't believe you got rid of your 406. :eek2:

[44oEX]

did anybody ever think that if you just sit there and rev the motor the pipe will get hot and glow red:huh . if you just rev it up and no air is cooling it down it will get hot. and when metal gets to hot it glows red.