i want to know what is the best way to get power on a 400ex i was thinking cams but i am not shur

 

I'm sure a good cam will really make more power cause it lets more air/gas in for every stroke of the piston......almost like a small turbo or somthin'

since I've not done it...I'm only guess'n ...It will prolly rise your compression too....so you may need a higher octane fuel....

 

a cam and piston is a very good setup for starters. you can run around 10.5:1 to 11:1 compression, or less of course, and still run premium pump gas. this will dramatically improve your power output. a nice full exhaust system is very helpfull as well.

 

what about a 440 kit, i dont know how those r with power or whatever.

 

If top speed is not a concern, droping a tooth on the front sprocket is the best bang for the buck!!

 

i was thinking about a 440 kit but i dont know how much i would cost to have my head bored and i alreddy have a 14 tooth sprocket 1 tooth smaller than stock and i dont want to lose much top end

 

ok, the head does not get bored. the head is what holds your valves into place. the cylinder is where your pistons moves in and this is what gets bored out. a 440 kit will require you to get a new sleeve and then get old sleeve pressed out of yoru cylinder. then your cylinder will need bored out and the sleeve will need to be pressed in. if it was me i would go with a smaller bore such as a higher compression stock bore, 406, or 416. this way you do not need to get a new sleeve. with these bores you can just bore out your stock sleeve and be done with it. a local atv shop will be able to do this. the prices vary. around here i usually pay around $75-$100 for the boring. other places will be cheaper. if you do add a piston i would make sure you add a cam. the 400ex cam is mild in the first place so it definatley needs upgraded.

 

sorry about the head cylinder thing i forgot i will have to get a price for the bore and stuff from my local shop he's cheap for around here but i will have to see i'll have to ask him about what bore i should get seeing as he as a 440 kit in his ex and i think i might put some 450r shocks on to i'll post back if i do it