i have a 2000 400EX with an FMF powercore 4 silencer, stage 1 hotcam, stock gearing, and except for the cam, a stock engine. i'm looking for the best, and cheapest engine mod available. i want power, and speed. i don't want my quad to be fast and not be able to climb hills. i also want to be able to run my quad off of pump gas, right now i use 91 octane. what r my options?

 

get a trx450r or yfz lol....nah go for the big bore with a high compression piston then u will be happier

 

will i still be able to run pump gas? and the only big bore kits i've seen cost like $400+ i can't afford that.

 

sparks flywheel key
remove the choke
rejet

just a note. if you go big bore you will need to change the head bolts to the larger size which is going to cost even more. I think it's about $100 to get them done

 

i've re-jetted, and my choke doesn't work. i have it zip-tied open. what is the point of removing the whole thing? and what's a sparks flywheel key?

 

get it port and polished its a cheap mod. for me it was only like $110 great increase in speed and hp

 

ok, thanx.

 

the choke restricts air flow due to how thick it is. and the key will advance the timing 6 degrees.

 

bigger carb (38-40 mm fcr)

 

ok, i don't want to sound like an idiot, but what's the point of advancing the timing? i'm not completely sure what the timing is in the first place.