Topic: CB750 K8 or F3 Carbs?

[tinyrobot]

When I was working on unsticking my throttle I noticed something odd.  The carbs on my CB750K8 have the throttle return spring coiled on the throttle link set.  I thought that was on the super sport F3 carbs.  I bought the bike with these carbs and 4-2 exhaust instead of the 4-4 stock.  Will the F3 carbs be ready for a 4-1 similar to MAC or Kerker?  Oh yeah so throttle rolls smoothly now, got it started but cyl. 4 would not fire.  So I swapped plugs with 1 and now 1 and 4 will not fire!?!?! 

[scondon]

   K8 and F3 carbs are the same except for jetting as far as I know. K8 carbs came with 110 main jets, F3's had 105 main jets. Might be differences in the air jets but not certain. F3 carbs have PD42A stamped on them. K8 carbs are stamped PD42B. I think either should be fine with 4-1 Mac exhaust without any changes.

  Are you using new plugs?

[tinyrobot]

The plugs are old, I just cleaned and regapped them.  New plugs are first on the to do list.  What about the return spring?

[scondon]

The plugs are old, I just cleaned and regapped them. New plugs are first on the to do list. What about the return spring?

   If I understand your question correctly....... Yes, the big return spring(coiled about ten times)is on the bar between #3 and #4 carbs. One end connects to the idle adjuster screw stop plate and the other connects to the back of #3 carb.

78 carbs are on the right

[Hockers Choppers]

These carbs have a very strong return spring. Lube your cable well,  and it won't seem so bad. OOPS, that sounded bad

[tinyrobot]

Thanks for the help.  I was just confused because the work manual for the K8 showed the return spring attach from the bar to the stay plate.  I guess it doesn't matter as long as they spring back 

[Hockers Choppers]

probably the wrong pic in the manual. The pumper carbs all have the coil spring around the rotating shaft.