what size jet help please

[cc_z400]

a friend of mine has got a 2005 400ex he put a FMF PowerBomb header with a HMF slip on k&n power lid with a k&n filter also a big gun cdi box.it had a 175 jet witch seem to run lean before power bomb header.with the mods done to the 400ex witch jet should he use.please help

[JOEX]

What makes you or him think it's running lean?

[cc_z400]

really cold natured some times falls on its face,sometimes when rideing like yesterday it just died on me three times.he only changed his main jet.sometimes boggey in low rpm,he has never had to change a plug since brand new,not all the time some times the header will glow orange thats why he thinks its running just a little to lean

[CarGuy7a]

it sounds to me the complete opposite. sounds like his main circuit of the carb is too rich and the pilot circuit is too lean. this will cause a bogging sound because at idle to half throttle it's not getting enough fuel from the pilot, then all the sudden when at half throttle it's getting too much from the main jet.

try a 160 main and a 40 pilot at 1 3/4 turns out on the fuel screw.

[cc_z400]

ok thanks carguy i will have him try that but if that does'nt work all help on this matter will be greatly appreciated

[Dill]

I would try a 40 pilot and a 155 or 158 mainjet. 175 is too rich in my opinion.

[CarGuy7a]

sorry i didn't specify my jet brand in my post. the 160 i'm referring to is a 160 dynojet main. which is a different size compared to a keihin jet. i'm not sure what the equivelant is from dynojet to a keihin jet.

the 40 pilot jet is a keihin jet.

[j450rking]

here is a jet sizing chart

jet sizing chart


Width------Keihin # -- 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
0.0630---- 162.5------- 148--------- 138.8
0.0640---- 165--------- 150--------- 140.6
0.0650---- 167.5------- 152--------- 142.5
0.0660---- 170--------- 154--------- 144.4
0.0670---- 172.5------- 156--------- 146.3
0.0680---- 175--------- 158--------- 148.1
0.0690---- 177.5------- 160--------- 150.0
0.0700---- 180--------- 162--------- 151.9
0.0710---- 182.5------- 164--------- 153.8
0.0720---- 185--------- 166--------- 155.6
0.0730---- 187.5------- 168--------- 157.5
0.0740---- 190--------- 170--------- 159.4
0.0750---- 192.5------- 172--------- 161.3
0.0760---- 195--------- 174--------- 163.1
0.0770---- 197.5------- 176--------- 165.0
0.0780---- 200--------- 178--------- 166.9
0.0790---- 202.5------- 180--------- 168.8
0.0800---- 205--------- 182--------- 170.6
0.0810---- 207.5------- 184--------- 172.5
0.0820---- 210--------- 186--------- 174.4
0.0830---- 212.5------- 188--------- 176.3
0.0840---- 215--------- 190--------- 178.1
0.0850---- 217.5------- 192--------- 180.0
0.0860---- 220--------- 194--------- 181.9
0.0870---- 222.5------- 196--------- 183.7
0.0880---- 225--------- 198--------- 185.6
0.0890---- 227.5------- 200--------- 187.5

[hotrodhonda400]

i'm runnig a 165 Kehin with close to the same mods and it runs great

[cc_z400]

ok thanks hotrodhonda he has been working on it all night i will let him know thank you