I picked up a set of old SU HS 6 carbs through a trade on here... Today
I set out to break them down...(The history of these carbs are unknown
to me.) I thought I'd share an observation that could be key to
problems some people have been having with getting a low idle on their
ON both carbs... I could see that the butterflies were not closing
completely. I could see black carbon buildup, around the butterflies,
where they were not closing...and they clearly could not close all the
Just to see if there was a mechanical fault for this... I loosened the
two set screws that hold the butterly... and tried to adjust them...
they immediately fell into the proper position... and now the
butterflies would close properly... and completely. That simple.
This problem has been discussed on FOT by myself and others... I just
thought it would be good to share the experience of finding it on this
old pair of carbs. I'm willing to bet, that these carbs drove the
previous owner crazy...
Food for thought. Make sure your butterflies can close tight!
Otherwise... you'll probably never be able to get a normal idle.