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CB400f - carb Air Screw query. Two screws different appearance ?
400 Cafe Racer:
Hi Guys,
Just getting down to adjusting the carbs after the engine, strip, inspection, rebuild. I have noticed that 3 carbs, 1,3 and 4 have a black largish air screw that will only rotate 270 degrees before it meets a "stop" on the carb casting. (Picture 1)
Carb 2 has a smaller diameter screw with a spring which looks like a conventional type that will screw all the way in or out over several turns.
(Picture 2)
Have you come across this ?
Nurse Julie:
Photo No. 1 is a home made bodge. All 4 should be the same as your photo No. 2
K2-K6:
That type (black plastic with limit stop) is used on small garden machine carburettor and possibly some other application too.
It's ordinarily a cap with limit stop incorporated that is pushed on to a brass airscrew with serated top. They'd be installed and adjusted to specification in "turns out" then the cap put on top to just allow limited adjustments in the field.
Wondering whether it's come from something like that.
400 Cafe Racer:
Hi Julie,
Thanks for your reply.
Having blown up the photo 1 on the black screw I wondered if this was some sort of plasitc capping fitted to limit the amount of adjustment that most owners would make, ie only 3/4 of a turn from each end of the stop. They seem softish as you will see from the screwdriver markings on the slot.
They look well made and mate exactly with the protruding stop which is cast into the casing.
I thought I may have read somewhere on a thread that Plastic cappings were fitted, but many haven't survived after 40+ years.
Maybe someone will be able to comment on this. ?
Regards
Dennis
McCabe-Thiele (Ted):
When I strpped my carbs down three had the plastic stop - one did not - it looked as thought the plastic cover had just come off - this stop if I remeber right limited the number of turns you could rotate the screw.
I found a used replacement on e-bay.
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