Swapping jets on mukuni vm26

[Icculus88]

So I have a 79 gs750 and it had modified air box and 4>1 exhaust. Specs show 100 mains and there are 105s in now. After rebuilding carbs and getting k&n pods she runs rich. With choke engaged she starts up at 4,000rpm compared to a normal 3,000rpm. The plugs are sooty and mileage is at about ~35. She doesnt have the power at say 1/4 throttle she used to and seems to gurgle/bog a bit more. exhaust smells a lot like fuel as well. I just got new mains. I ordered 117.5 and 120.

I'm about to swap the 105s out for 117.5. Any suggestions on tuning?


Thank you very much,

Pat

[Big T]

Everything you've said is backwards

If you've got 105 and it's rich, why would you go to a bigger jet?

Although, from your set up, 117.5 should be about right

Racing idle indicates lean condition

Also, what are the other specs?

Pilot jet
Air screw
Fuel screw

[Icculus88]

How should i go about fixing the richness problem?

[Icculus88]

ok so i am swapping mains to 117.5, checking to see if pilot jet is 15 (I have spare 15'ss), and checking fuel screw and air screw.

Would the pilot jet be responsible for the high idle?

[Agemax]

if it is running rich on 105's then going to 117.5's is going to make it a whole lot richer!

[Icculus88]

ok so air screw was only one turn out. should have been two , im going to go start her up and see what happens

[Icculus88]

ok so adjusted air screws and idle screw. She seems to be running nicely, i didn't go on a long ride just up and down the block. Bottom end seems better. Exhaust definitely doesn't smell like fuel like it did earlier. Idle seems more stable. I will put in 117.5 mains, adjust fuel screw and check pilot jet size tomorrow. Then i will see how she rides all around. Thanks for your input,

-Pat

[coolio]

I have a gs750 1977 with the same carbs and am about to change the main jets to 110. I have pods and a 4 into 1 exhaust.

How did your 117.5 work out?
Dave