How did it run with the stock pipe on? If you had to re-jet with the FMF pipe, chances are youll have to jet back down.
It shouldnt "ruin" your motor if you dont (The fuel is not the primary lubricant of your motor, but dont totally starve it either!), but if it your 400ex runs like crud, why race at all? I'd say re-jet.

RoostKing...

 

My FMF pipe cracked do to factory defect so i sent it back and they are sending me a new one. Problem is itll take a while and i have a race this weekend. I put my stock pipe back on and my question is am i going to have to go through the hassle of rejetting for the race and then do it again when the pipe comes back or can i run it for a day and not ruin my engine. Thanks


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~~Mike

'99 400EX, FMFpower core IV, WB Triple rate shox, AC Nerfs, K&N Power kit, Renthal Bars, etc...

 

MY FMF PIPE JUST BUSTED, I GOT MINE THROUGH ROCKY MOUNTAIN ATV, SHOULD I CALL THEM OR SHOULD I CALL FMF. MAYBE I SHOULD JUST REWELD IT. WHAT SHOULD I DO
PLEASE HELP!

 

I just put an FMF PowerCore on my 400EX. I plan on using the stock air filter. My question is, what changes do I need to make with the jets. I've heard that the dynojet kit causes some hesitation in throttle response.

Bruce Crowe
99 400EX
99 Wolverine

 

I have a FMF PowerCore IV on my 400EX with a K&N. I also installed the dynojet kit using the main jet and other mods recommended in the kit instructions. I have not noticed any hesitation in throttle response - it rips.

 

are u racing at diamondback

 

I raced at Embarass River. I wont be racing the for a while though, i rolled in 6 times off the double, it sucked. Oh well, lifes a bitch, then you marry one, right?



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~~Mike

'99 400EX, FMFpower core IV, WB Triple rate shox, AC Nerfs, K&N Power kit, Renthal Bars, etc...

 

team400ex,
Running a little rich won't damage any engine, 2 or 4 stroke. The worst thing that can happen is a fouled plug, & that would be more of a possibility on a 2 stroke. Running lean is what causes engine damage.As a temporary fix, drop the needle one notch. It may help in the mid-range area. The various jet settings overlap somewhat, so this may correct any rich mixture. Don't forget to raise the needle again when your pipe is installed again

the Az Hardpacker,
calmiller@kachina.net

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[This message has been edited by hot_shoe_cv (edited 08-31-1999).]

 

LDJ,
I suppose it wouldn't do any harm to call Rocky mtn. altho, I wouldn't hold out much hope as they would assume it was a rider error. I see no reason a good welder could not take care of the problem, assuming the shape or any bends remained the same as before. If he were really skilled, a nice even bead of weld would be hardly noticable.

the Az Hard Packer,
calmiller@kachina.net

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