1978 CB750 F2

[blackeagles]

Most carbs usually have the pilot air screw setting as 'x' turns out +- 'n' but the 'H' Manual and a couple of bits I have seen on the net say the pilot air screw should be 1 3/4 turns out without any +- so is this correct?

I also hate to ask this but is it in for less air and out for more 

[K2-K6]

Understand the confusion as to direction,  no  there as they differ from the older K type which is not always acknowledged.

Generally "idle mix adjust screws" on airbox side of carb venturi are opposite to the same screw when located on the engine side of carb venturi as the F2 is.

At 1 3/4 out,  the screw is at a reasonable start point to run the engine,  then there is a routine in official H manual to fine tune each screw and optimise slow speed running.  It's a very clever little loop that looks insignificant but is how they should be set and allows for differences from one carb to the other in setting equality of combustion so that they match for each cylinder.

Anyway,  it should be OUT for more fuel on these carbs.

[blackeagles]

ok, thanks.

not easy to do no2 is it?, keep burning my hand (boho)

anyway having set and reset the pilots,  it seems to like 2 3/4 turns out which seems rather a lot not it ticks over evenly with hardly any 'hunting/faltering'.  there is very little difference between 2 and 2 1/2 other than the revs dropping a hundred or so.

is 2 1/2 or 2 3/4 too much?

[royhall]

My F2 runs perfect at about 2 1/4 turns out so your in the ballpark.

[K2-K6]

As above by Roy,  it looks like you may be too far out there. It should be going rich at 2 3/4 turns out which is why you get the revs drop.

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From Honda workshop manual including procedure.

Unsure of your knowledge of these carbs? But they set them close to optimum (leaner than non accelerator pumped type) as its supplemented by the pump as you open the throttle,  too rich (or how people generally set non pumped carbs) idle setting can give a flat spot as you start to open the throttle with combined total fuelling going too high.  So they,  in comparison to conventional setting, should sound slightly lean. If that makes sense 

[blackeagles]

hi guys, thanks for the info.

the 2 3/4 turns out is the highest tick over speed I get (I have tried 3 out  but if reduces the revs so too far!), and the revs slightly drop when I back it off to 2 1/2 out so maybe 2 1/2 is ok for this bike - I don't know these carbs (i'm vintage british and harly) but until I get it out on the road (a while yet) I will not know if this setting is ok or not.

thanks again