Choose My Jets (Please!)

[NeonImpact]

I have the HMF slip on right now with NO jets and it seems to be running good.

I just ordered the FMF powerbomb header and are about to put this on.

But before I do, I need to know what Jets will I need?

Will be installing on a 440 big bore kit and closed air box.

I live in Southern Maryland (close to chesapeake bay) so I'm not sure what the sea level is.

Thanks

[NeonImpact]

Please? :ermm:

[RiderTRX400ex]

a lot of the jetting is trial and error, but start out with a 160 main jet, and see how that runs, checking your plug.. you will want your plug a cocoa brownish color, whiteish is lean, and like a soot black is rich. Look into a dynojet jet kit or other jet kits since they come with many different jets, and a new needle.. Im sure others will post some more help too

[NeonImpact]

Thanks for the reply.

I already have these jets, but are unsure if they would even be worth trying.

42 pilot
155,160,165 main

[MX174]

i ran a 440 with a big gun full system and used a 42 pilot and 155 main. I never checked my plug and all but it seemed to run fine, i also used a stock filter and a uncut lid.

[Warnerade]

Originally posted by MX174
i ran a 440 with a big gun full system and used a 42 pilot and 155 main. I never checked my plug and all but it seemed to run fine, i also used a stock filter and a uncut lid. its a bit late for april fools jokes man...

[Kyle_Racer_31]

Originally posted by NacsRacer027
its a bit late for april fools jokes man...

I rode the 400 all the time never cracked, pop, or cut out....Plus U r a lil late on April Fools NAcsRacer

[MX174]

actually I wasnt joking , the damn thing ran fine for the way I rode and had a crapload of power over a stocker, never cracked or popped. Oh well some people just need to try **** sometimes, and see what works for them.

[Kyle_Racer_31]

There is alot of people on this Site that needs to learn to believe other people....

[Warnerade]

kyle...shut up.

and mx17...were you running a dynojet or just a regular jet...becuase i had a 416 national engine with an FMF full exhaust...and i ran anything from a 190 to a 205 at one point or another...i was well over 155 with just an exhaust. if it worked i guess it worked...it just comes across me as odd

[Kyle_Racer_31]

Originally posted by NacsRacer027
kyle...shut up.

and mx17...were you running a dynojet or just a regular jet...becuase i had a 416 national engine with an FMF full exhaust...and i ran anything from a 190 to a 205 at one point or another...i was well over 155 with just an exhaust. if it worked i guess it worked...it just comes across me as odd

Go Suck A Big One

[Warnerade]

Laugh Out Loud, Please Get Back On Topic.

[MX174]

just a regular jet, i was suprised myself that it worked as well as it did espically since i wasnt running any kind of a cut lid or aftermarket filter. Im also from Illinois and i dont know what sea level were at so that might make a difference.

[Warnerade]

i dont think the difference at sea level between us would make a diffeerence of 50 in jet sizes..but o well, i guess some engines act different than others

[cals400ex]

on a stock carb with my built motor i would get up to around a keihin 162 in the coldest of weather here and a modded air box lid.

mx, i ran a keihin 158 with a similar setup as you.

i notice a drastic loss of power in the upper rpms by going larger than a 165.

[NeonImpact]

Well in my case I guess ill just have to run these:

160main
42 pilot

:confused:

[Ocnaj]

Some people have to start to learn that all engines are not exactly the same, there are no 2 engines that are precisely similar inside and out. This has nothing to do with jets but its just my input.

[NeonImpact]

Since ill be going 160 and 42, do you have any tips on the right adjustment?

Thanks all.



The 160 main and 42 pilot should be a decent starting point and the fuel screw at about 2 - 2 1/2 turns out from lightly seated.

Sound Correct?

Needle clip down 1 position?

[cals400ex]

i would probably start with:

158 main
42 pilot
2.5 turns out from lightly seated
needle clip down one position (4th position from the top)