dynojet size conversion

[rap169]

i have a dynojet kit for my 400ex carb. No with my motor mods, i ned a larger jet than the dynojet 170.
I want to buy a keinin (however its spelled) jet pack. It includes five main jets. I just dont know what size since they are different than dynojets. can anybody tell me what a dynojet 170 is equivalent to? Thanks

[cals400ex]

i hear a 170 dg is bigger than a 170 keihin. i don't know what bike this is going on, but a 170 is too big for a 400ex unless it is heavily built.

[northeast400]

I ran a 165 dynojet on my 426 and it was too big. If it is stock try a 146 dynojet and go down from there until lightly lean, then go up one mainjet size

[nastynotchback1]

i am running a 175 dynojet at 300ft above sea and before the cam it didnt crank well and seemed to be rich.installed the cam and it cranks alot better and the jetting is fine know.

[rap169]

well its the 400 carb on my 250x. The motor is modded with a wb head pipe and silencer, no air box lid, wb race cam, weisco psiton, head has been ported and polished wiht oversize valves. I had a 165 in it before the head work and i was a tad rich. But with the head work, it seems really lean. I started form the piolot and then the needle and they both seem good. I then did a plug chop test for the main and it was grayish, not brown yet. It also seems to flatten out at on the top end at wide ope throttle.

[mustang93]

I think your way too rich.:confused: :huh

[DantheEXman]

Im having the same problem... I have a 170 main in it now and its running way lean. Plug has white on the tip. I think its the degree key.

[cals400ex]

it could be just the brand of fuel or too low octane fuel. also, are you doing a proper plug chop?

[camsdad]

i'm at sea level and around 145 seems to do the trick...

[DantheEXman]

cals you were right. I didnt have high enough octane fuel. 93 seems to keep the 11:1 compression happy. It seems to run rich now. Which is much better than lean. Now I just have to fine tune it.