GS750 Carb Confusion.

[Redvettenc25]

Alright Bought a 79 GS750 about 2 weeks back. Didn't run when I bought it. The PO evedently lost the air box so now I am running pods.
First thing I did was change oil, sparkplugs, ensure proper timing and fire on all cylinders, check compression (all around 120 psi), dissassemble carburetors cleaned and replaced orings on all jets.
So now I am to the tricky part and am getting frustrated.
I got her running on the stock jets but of course, it was too lean because of the pods.
I used duct tape to restrict air intake from the pods and richen the mixture.
The bike ran fine with the duct tape on the pods. Reved good and whatnot.
So I found some other jets from my old cb750 that were 120's. I have read some of the carb post on here and thats the size jet it says to start at with pods. So I threw them on the carbs.
Now it seems that the bike wont start at all.

What is the difference in the two styles of jets essentially? The cb750 jets are smaller diameter but have larger holes in them and thread in correctly.

Does the needle sit incorrectly in these jets?

And do I need to set the needle down one click like it says in other posts, it seems that setting the needle down one click would lean out the mixture instead of richening it up. Seems like you would raise the needle one click to richen the mix up.

Thanks in advance for the feedback. Seems like I should have stuck with the CB's.

 

[Redvettenc25]

Also I am not using the petcock since I have a new one ordered I am direct feeding the Carbs through a supplement tank.

 

[SVSooke]

No expert here but IIRC Keihin and Mikuni jet have completely different numbering systems.

 

[Redvettenc25]

Yeah thats true. Hmm mabye should get a jet comparison size chart.

 

[Redvettenc25]

Jet Comparison Chart.

Width------Keihin # -- DynoJet # -- 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

 

[Redvettenc25]

So In theory the jet I put in is a 107 so it should still be bigger than the stock 100. Grrrrr.