i am putting a hotcam stage 1 in my 05 400ex. i have a pipe, jet kit and the whole 9 yards. no racing piston so not quite the WHOLE 9 yards, but anyways. it is jetted spot on right now. will i have to rejet when i put the hot cam in my EX or not? has anyone else put a cam in a stock(piston) 400ex? did you notice a power increase. let me know about the jetting question please.

Travis

 

I had to for my cam but u might not so i dunno just start it up afterward and see

 

seems odd to me to buy a cam and not spend another $150 bucks for a piston, rings and gaskets. Usually most cams are designed to run at least with a one size over piston.

I just put a hotcam stage 1 in my raptor, and it recommended a high-comp piston (which I got from Wiseco) and a good pipe ( I replaced my big gun with an LRD Pro4). I am in the process of rejetting.

I would think you probably have to rejet, as the cam changes the rate at which your exhaust and intake valves open, and your engine will therefore probably draw more fuel. So you might want to up your mains, or at the least adjust your needle.

stage 1 cams are usually low to midrange cams. you will notice an increase, but I'm not sure how much with just a cam and not a piston.

 

the key is the cam....it alone will provide more power increase than most other upgrades new piston or not...but you will not unlock the true potential of it without new intake & exhaust...infact your quad will run like chit unless you allow it to flow better

efi are a little more complicated