Hey guys just bought a 400ex got some ??'s

[ModManiac]

I just purchased a 2003 400ex, its all stock and Ive had a raptor before so this quad feels a little under powered for me. What is the best exhaust to buy for this thing? I was thinking of going HMF but cant decide between the full header or just the slip on. Also what Jets do I need to use?

[underpowered]

do you plan to other mods later? if you plan on doin other motor mods go witht eh full system, if you just paln on doing the pipe and tahts it athe slip on will be fine. a full system does not give you much more of a gain than just a slip on on a stock bike.

jetting is a science, we can only give you a starting point. you have to fine tune from there. call HMF and see what they recomend for your area and bike. i would guess like a 155 main, a 40 or 42 pilot and about 2 1/2 turns of the air screw.

[ModManiac]

Im located here in Kentucky, I may plan on doing a cam but worried about the difficulty of instalation and if it will really make a difference.

[400exMO]

I agree with underpowered. If you're doing more get the full. But I would have to say if I was getting a full I'd get a sparks.

[GYOGI65]

CAM MADE BIG DIFFRENCE IN POWER BUT DONT GO CHEAP DO CHAIN AND TENSIONER AT LEAST MAYBE GUIDES TO
HEAVY DUTY CHAIN FROM XR 400 I THINK WORKS GOOD
DOUBLE CK EXACT BIKE MEMORY FAILS ME BUT WORKED WELL ON 2000 REBUILT FOR MY SON

[Bigun55]

I agree with both of them

[ModManiac]

I wound up buying a Curtis Sparks full exhaust I think its the X6 series. I may be having a problem with jetting as a 170 is too big and it backfires with a 162, both are Kehin jets and this was the only thing I changed on my carb, stock pilot jets and the needles in the stock location. BTW I live in KY.

[nightmare311]

hd timing chain for a 400ex is a 2002 crf450 timing chain. fits perfect. i got one in the motor im selling.