Now that I have your attention here's the story. I'm not bashing, I actually want help with my buddys 400ex. I have a 2002 Scrambler 400 with a pipe and silencer, clutch kit, K&N, and rejetted. My buddy has a 2000 400ex with cut front fenders, a White bros e series, 12 tooth front, rev box, K&N, and rejetted. Two weeks ago we went to Glamis and raced up Olds and on the road to Boardmanville, in each race he would jump out in front about 4 bike lengths and thats where he would stay, I couldnt catch him and he couldnt pull away. Since then he got a 6 degree timing key and when we went to Glamis this past weekend and raced up Olds and to Boardmanville I pulled out front and ended up about 4 bike lenghts ahead. Whats the deal? Does he have to rejet? We rechecked the instructions and he did put the red mark out. Could it be over advancing now? I dont know what brand of rev box he has.
Any help would be appreciated because he doesnt want to ride anymore until he gets a big bore kit[img]i/expressions/face-icon-small-happy.gif[/img]

 

I think degree keys are mostly for internally modded quads, like strokers and big bores, with ported heads and such. For "fine-tuning", so to speak. I don't think bolt-ons would give the need to change the ignition timing, although I could be wrong...

 

just adding a part doesn't always make a quad faster, as your friend found out.

 

sparks actually doesn't recommend the keys for high compression motors due to the extra heat produced.

he needs to take that 12 tooth sprocket off and put on a 14 at smallest. he would actually have best gains running the stock 15/38 in my opinion.

 

its still the same old crappy 400ex..lmao

 

it could be altitude too. we're told here at 4000' alt to not buy those things.
Ive always been skeptical about those.. on a truck it would fry valves and maybe hole a piston. I'd take the thing back out.
there is no magic solution, its a combination of parts properly balanced. this apparently aint one of em hehe. have him remove it before he does some expensive internal damage. he can sell it on like ex riders ...someone will want it.
JMHO [img]i/expressions/face-icon-small-smile.gif[/img]

 

i'm actually supised the 400 ex won at all some of those scramblers are reasonably fast.

 

12 tooth front? i can see that on a flat drag...

 

That was my mistake, its actually a 14 tooth front.

 

that sounds a little better