jetting help please

[Selland74]

here's the deal. ive got a 400 with a big gun full system, hotcams stg 1, and K&N. i was running with the airbox lid on but i decided to take it off and jet up. so i took out the main and it was a 146. (i bought it with the pipe on it and the previous owner had done the jetting) i thought this was wierd since stock is a 148 right?

anyways i put in a 158 and it ran about the same. so i decided to change the needle and pilot. i moved the pilot from 3rd to 4th from the top and went from 38 to 48 pilot. while i was in there i removed the choke.

i started it up and it runs like garbage. im thinking the 48 pilot is too big and i need to go down to a 42. its hard to start and doesnt idle very good. In mid throttle range it really sputters and backfires some.

any suggestions. the 146 main really confused me because a lot of people on here say they are running like 160 or 165

thanks

[JOEX]

Originally posted by Selland74
here's the deal. ive got a 400 with a big gun full system, hotcams stg 1, and K&N. i was running with the airbox lid on but i decided to take it off and jet up. so i took out the main and it was a 146. (i bought it with the pipe on it and the previous owner had done the jetting) i thought this was wierd since stock is a 148 right?

anyways i put in a 158 and it ran about the same. so i decided to change the needle and pilot. i moved the pilot from 3rd to 4th from the top and went from 38 to 48 pilot. while i was in there i removed the choke.

i started it up and it runs like garbage. im thinking the 48 pilot is too big and i need to go down to a 42. its hard to start and doesnt idle very good. In mid throttle range it really sputters and backfires some.

any suggestions. the 146 main really confused me because a lot of people on here say they are running like 160 or 165

thanks
Most likely the 146 main jet came from a 'jet kit' which have a different numbering system. Generally the jet numbers on the 'kits' are smaller than stock style jets. 146 is a common size for the 400ex with mods.

Also, I belive the jet kits use an adapter for the main jets.

[CarGuy7a]

Originally posted by JOEX
Most likely the 146 main jet came from a 'jet kit' which have a different numbering system. Generally the jet numbers on the 'kits' are smaller than stock style jets. 146 is a common size for the 400ex with mods.

Also, I belive the jet kits use an adapter for the main jets.

yup. define what type of main jet was in it. a round jet with a hex adapter is from a dynojet kit most likely.

just a plain hex jet is a keihin jet. and yes the sizes are different.

for example a 148 keihin jet is a little bit smaller than a 148 dynojet jet.

[AnDy7]

i had found this on the hmf website , not sure if it would be the same for all exhaust or not though.

Honda 400EX:
1999 - 2003 Slip on:
165/170 Keihin Hex

Honda 400EX:
1999 - 2003 Full System:
180/200 Keihin Hex

Honda 400EX:
2004-> Full System & Slip On:
152 Keihin Hex / 42 Pilot