Honda-SOHC

I had a misfiring problem that wouldnt go away and after cleaning the carbs and replacing the brass, I realised that the needles need to be changed as well as the replacements are subtly different. I went back to my original brass and needles and after all the cleaning and balancing it runs beautifully again.

True, but it “might” be a good? 😌

This set seems too cheap to be any good?!

https://www.ebay.co.uk/itm/195978773341?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=a5qr2fnqtcu&sssrc=4429486&ssuid=wmWanCu3SsS&var=&widget_ver=artemis&media=COPY

All the original cables i saw in the 70's had a black lining on the inner cable and should have had a white inner coating on the outer but you only saw that if the outer was damaged.
I also know for a fact that the taiwanese manufacturers at the time would package anything in the way the buyer asked, i bought many Yamaha FS1E cylinders in packaging identical to original.
Honda cables normaly had the part number in white on the outer sleeve.
I doubt that Honda will do anything as you do not know where it originally came from, that dealer is gone so cannot provide purchase details and finaly time in stock

Yep, you described the way an air screw works.

I wrote to Mark directly, to double check what he had written and he confirmed:
"The idle-air screw in those carbs (all of the 750 roundtop carbs) controls the amount of fuel-air mixture that gets pulled up for each intake stroke. It is already mixed as fuel & air inside the tiny tube on the top of the idle jet, where those holes are, when air from the little brass orifice at the back of the carb's bell met the rising fuel in the jet's metering hole. Then, the position of the screw admits more (or less) of this mixture during the intake suction."


I am testing this now. I had 2 lean plugs and 2 sooty. The lean I opened up 1/8th turn. The sooty, in 1/8th. I have found two of my lean showing plugs are tan and one of my sooty plugs is improved. The other is still sooty, so I am trying a further 1/8th in.

All on non-ethanol fuel, but general riding, not a strict plug chop, as I believe my needles are in the right position, stock jets, airbox, 341 exhaust etc. Points set, timing checked, ditto valve clearances. Carbs are cleaned, synch'd and float levels triple checked. Although I do find float levels a little tricky.

So, not conclusive, but the early signs for me is following this advice has given me a small improvement.

I apologise if this has taken us away from@Pauarc's original problem. It could be relevant. Not difficult to just give it a try, after adjusting the floats to spec. 👍