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post #1 of (permalink) Old 07-20-2003, 06:49 PM
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jet kit problem, 400ex

i recently bought a 2000 400ex off a buddy of mine, and it has a jet kit. another friend of mine has a 400 that is bone stock, and in a drag race he still beats me. i have 20 inch fast trekkers on mine and he has stock tires, would that have anything to do with it? another thing is the 400 i bought hasnt been ridin in about a year, so could that have anything to do with it being a little bit slower?
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post #2 of (permalink) Old 07-20-2003, 07:51 PM
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Re: jet kit problem, 400ex

well that could be the problem but he also has all stock so his is likely to be fasta what year is yours and his , cuz if yours is a 98 and his is a 02 that could make a difference
post #3 of (permalink) Old 07-20-2003, 07:53 PM
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Re: jet kit problem, 400ex

sorry my bad i furgot u said it wus a 02"
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post #4 of (permalink) Old 07-20-2003, 08:59 PM
 
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Re: jet kit problem, 400ex

it could easily jetted wrong, jetting is a very hard thing to be 100% with, why is there a jet kit in it? filter? pipe? any air flow changes? why would he put a jet kit in if nothing performance wise was done to it...sounds kinda iffy

the tires should have nothing to do with it, your tires are a bit heavier I bet, but there the same size and it wouldnt make a noticable difference

Usage has nothing to do with it, unless it was beat to hell, so from the sounds of it, its either a poorly jetted quad, running rich or lean making it run like crap and fall behind in a race, or this kid you race is just a plain and simply better rider [img]images/graemlins/grin.gif[/img]
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post #5 of (permalink) Old 07-21-2003, 06:46 AM
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Re: jet kit problem, 400ex

I have a 2002 400ex I bought new last year. The 400ex is very hard starting with stock pilot jet. It's too small. I took the advice of YZROOSTINYA and replaced the 38 pilot jet with a 40. I also replaced the stock 148 main jet with a 150. I removed the two screws holding on the choke plate and removed the plate. It gets better flow with it removed and the choke on the 400ex is pretty much worthless. Now the bike starts real easy and it runs better w/o that plate. I then swapped out my 15t front sprocket for a 14t. It accelerates much harder now through the gears. It lost may 3-5mph on the top, but I rarely have it screaming in high gear anyways/ perhaps on the street or in an open trail. Perhaps your buddy dropped a tooth also. ??? My stock 400ex with the mods I did will outrun my buddies 400ex with full pipe and K&N, but he has the stock gearing.

I still have the stock exhaust and air filter/box. The gains from the pipe and K&N I don't think are worth it on the 400ex. Maybe 1 Hp with slip-on and 1-1/2 with full pipe (jetted of course). I like it quiet as it doesn't draw attention. Now if I had a Z400 or YZF, the gains from a pipe, air filter and jetting is a good 5-7 Hp.

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post #6 of (permalink) Old 07-22-2003, 11:56 AM
 
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Re: jet kit problem, 400ex

ya tony, I did the same to my 300, even though it started fine, it started better wioth the 42 pilot jet, I had the main already up a few sizes becasue no air lid, K&N and yoshi, with another turn out on the fuel/air screw I was going strong, took the choke of to, Gives a little bit more throttle response, well worth it sense I didnt even use it
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