HMF slip on/w 155 main and a black plug!

[muddy400EX]

my 400 used to run good until it got hot out, now its runnin a PITCH BLACK plug!, this is with a 155 in and a kn filter. i think im gonna have to put the stock main jet back in, cuz its black as night:confused: any ideas?

[cals400ex]

when did you check the plug? after starting it? after it was idleing? after a full throttle run?? are you using the dynojet kit or keihin jets? where is the needle clip located? keihin needle or dynojet needle?

[muddy400EX]

Originally posted by cals400ex
when did you check the plug? after starting it? after it was idleing? after a full throttle run?? are you using the dynojet kit or keihin jets? where is the needle clip located? keihin needle or dynojet needle?


all dynojet with the needle 2nd clip from bottom i think. i checked it after a 20-25 min. ride of running it hard. im thinking maybe i need to lean out the needle?:confused: would i need to move the clip up or down to lean it out?

[EvilJester400EX]

When you ran it hard, did you coast to a stop or shut it off immediately? Correct way to plug check is to run it wide open then shut it off, don't coast to a stop. I would go down on your main jet size one or 2 if it's pitch black.

[cals400ex]

i would move the needle clip up one slot. what pilot jet are you running? how many turns out on the fuel screw are you? a 155 may be a tad rich with the air box lid on. this is given your only mod is the hmf.

[plkmonster2]

Run the next lower main in the kit. I believe it is a 146. And move your clip up, to the 3rd from bottom.

[jak1389]

try taking your air box lid off.

[muddy400EX]

Originally posted by jak1389
try taking your air box lid off.


im already runnin it with it off, i moved the clip up one and took it down this little alley behind my house and it seems a little bit more peppy, like its not as rich. ill get to try it better tomorrow at the track. thanks for the help guys:)

[jak1389]

yea, so then maybe just take it one size down for the main jet, and when it gets cooler out put the 155 back in.

[coryatver]

my friend is running a 155 kehien jet with the lid on and it runs awesome. A dynajet 155 is a lot bigger than a kehien 155.

[400ex28]

152 ;)

[400exhauck]

i havea 400ex with an HMF slip-on, K&N, and no lid... im running a 170 main, with the needle on the 3rd clip down from the top... the plug is perfect... i rode it for about 30mins, checked it, then rechecked it after about 5 hours... brought it down to the honda service department and he said its perfect

[400ex28]

wow, a 170? im runnin 152 and its perfect

[400exhauck]

yeah... i brought the plug into service just to make sure and he said its just how it should be... i work down at a honda shop, so i dont think they'd bs me

[Speedy81304]

every engine is diffrent. I'm running a 150 main, 4th clip. and a buddy of mine with a 03 with mostly the same mods is running a 165 main on the 3rd clip. and both of the quads run hard and fast.
and the plugs look light brown. right where you want it. put it this way you could have ten bikes all with the same mods in diffrent parts of the country and they all would have diffrent jetting. dont go by what other poeple are running for your main setup. i would go by other setting as a start. because its a ballpark figure on the correct jetting.

[meanyellow03ex]

It seems that HMF pipes run a larger jet compared to other brand pipes. I've noticed this in magazine tests even on different machines like the Yamahas and such.

[markk]

AIR/FUEL screw!

Screw it all the way in and back it out 2 full turns. Put a new plug in and try it out!, Keep your 155 in matt. If you need some help with it sometime just gime a call, Im actully doing the same thing to my carb tommarow in the morning, (well when i get up, its 4;00am now)