400ex gots no high power

[Ebrown]

someone please help me, i recently purchased a 2001 400ex and i love it, but there seemed to be no power at high rpms in the gears, now im a 1sr time 4 stroke owner but long time 2stroke dirtbike rider, doesnt seem right and dont know where to start, i changed the plug and that helped a little...
maybe jets or carb ajustments? any advise is appreciated

[flauge]

A cam will prolly make a good difference on top end, cause from what i hear the stock one is pretty mild. 450r carb is said to help too..:cool:

[Ebrown]

i have a stage 2 hot cam in it now

[CHEVYZ]

What are all of the mods that you are currently running, and what kind of main jet do you have in it now? It is possible that your experiencing these top-end issues because bike is running too lean.

[flauge]

man i was about recomend that.I cant think of anything esle now. The carb would probably help.

[Wheelie]

What mods do you have and what jetting?

[Ebrown]

stage 2 hot cam, full exhaust (header and t4 slip on), k&n filter,
thats it as far as motor performence, maybe im running the wrong plug? its a champion d1007 or something. what is the ngk plug# that its supposed to have..
what size jet should i be running too?

the quad runs great at low rpms in the gears that its like in the top of any gear she bogs down, the throttle response isnt their..
thanks for all you help guys.

[-copyguy-]

pull the carb out, take the jets out and clean everything really well. I just found that I was losing top end because my main jet had a piece of something stuck in it...so instead of a 150 main it was more like a 120 main...

If response is good on the low end, your pilot is fine, but your main has something goin on with it.

[curious george]

ngk d9 somthing for high speed and a d8 for low speed. maybe it is in your gearing?

[awsomeaussies]

Plug is a DPR8Z I believe;)

[curious george]

Originally posted by awsomeaussies
Plug is a DPR8Z I believe;)

thats the one!!

0r you could get a dpr9z for high speed riding. i ran a dpr9z.

[Def-e-nition]

Good luck fnding a Dpr-9z though ...

run a Dpr-9EA . Motor runs cooler , and the plugs are easier to find .

That was a tip from mickey dunlap , and I am runnning that plug , with zero fouling on the plug . (do you know anyone that doesnt run his bike hard some time or another ??!?)

Perhaps you are simply used to 2 stroke power ? Those things generaly experience a peaky torque output , and with 2 strokes if i remember correctly , you normally tend to wind em up to get more power , with a 4 stroke it is not so prominent . stage 2 cam you should be flying out of the blocks pal .

Pm gp racer and ask him for some advice .

[Ebrown]

thanx again everyone, im gonna go buy that dr8 plug and tear into the carb, i didnt want to do the carb because i only have basic knowledge but hopefully its just gummed up or something.

glad to be a part of this forum you guys are a big help

[-copyguy-]

Ebrown, sent you a PM that might help...

[Ebrown]

thanx copyguy:)

[Ebrown]

well turns out im an idiot my quad runs fine, buddy of mine works at a honda dealership, said im stupid, im just so used to my 2-stroke...well thanx for all the help fellas:rolleyes:

[-copyguy-]

throw a nice HMF pipe on that thing...it'll wake it up a bit :D