jetting help

[gnccguy]

I am running a K & N filter, and the airbox is open with an HMF slipon. What number main jet would be close? I have a Dynojet kit and the largest jet in the kit is a 140. The kit calls for a 128 for my elevation and an exhaust. My elevation is under 3000 feet. I noticed where HMF says it should be around 165. Any help would be appreciated. Im wanting to rejet because i adjusted the valves and took it 4 a ride at night and it turned the header orange. perfectly in time and valves r perfect.

Thanks, Brad

[matt76]

I have an 07 450 with the HMF slip on with open airbox and uni filter. I too started around the 170 main and it would run fine but when I looked at the spark plug the thing was very dark. Ended up going to a 160 main, 45 pilot and 3 clip from top on HMF needle. Pulled plug after riding and its just right hope this helps.

[gnccguy]

how close do u think a 140 would get me because that is the bigest in my kit and the kit only calls for a 128 stage 2 for a exhaust and my elevation

[matt76]

Here is a comparison Kehein which I used on the main versus the dynojets. As you can see your 140 is equal to a 152 main in the kehein so you will be close..odd are you are going to run your needle higher up. Try it and if it bogs down at wide open you know your gonna have to go bigger on the main.




Width------Kehein # -- DynoJets # -- Mikuni #
0,0350---- 92,5--------- 92----------- 86,3
0,0360---- 95----------- 94----------- 88,1
0,0370---- 97,5--------- 96----------- 90,0
0,0380---- 100---------- 98----------- 91,9
0,0390---- 102,5------- 100---------- 93,8
0,0400---- 105--------- 102---------- 95,6
0,0410---- 107,5------- 104---------- 97,5
0,0420---- 110--------- 106---------- 99,4
0,0430---- 112,5------- 108--------- 101,3
0,0440---- 115--------- 110--------- 103,1
0,0450---- 117,5------- 112--------- 105,0
0,0460---- 120--------- 114--------- 106,9
0,0470---- 122,5------- 116--------- 108,8
0,0480---- 125--------- 118--------- 110,6
0,0490---- 127,5------- 120--------- 112,5
0,0500---- 130--------- 122--------- 114,4
0,0510---- 132,5------- 124--------- 116,3
0,0520---- 135--------- 126--------- 118,1
0,0530---- 137,5------- 128--------- 120,0
0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9

[gnccguy]

awesome man useful real useful

[gnccguy]

i cut a hole in my air box lid same size as the 1 where the factory snorkel went in. and it runs awesome with that 140 main jet. i run xc so i kinda like to have some air box coverage anyhow.

[feelthisroost11]

i opened my air lid and dropped a 170 in it. runs great