17-09-2020, 04:08 PM
Hi,
I have a 1 1/4" SU Carb on my Ulsteroid and have never had a problem with the idle speed although it was a pain to start which I put down to the very small head of fuel caused by the scuttle tank being only just above the carb. (It's mounted on an an angled adapter atop a downdraft manifold).
Recently I've had the Carb off and also fitted an electric fuel pump which has significantly improved starting.
Anyway since doing this the tickover is now a bit on the high side even with the adjusting screw wound right back. I have also checked the screw which slightly opens the throttle when the choke is operated and it's clear of the cam.
I believe leaks in the intake can have this effect but I only removed the Carb from the adapter it all looks OK.
Before I strip it down would a high fuel level in the float chamber have this effect as with the electric pump there's obviously much greater pressure in the fuel line which I guess could affect the level.
Any suggestions would be appreciated.
John.
I have a 1 1/4" SU Carb on my Ulsteroid and have never had a problem with the idle speed although it was a pain to start which I put down to the very small head of fuel caused by the scuttle tank being only just above the carb. (It's mounted on an an angled adapter atop a downdraft manifold).
Recently I've had the Carb off and also fitted an electric fuel pump which has significantly improved starting.
Anyway since doing this the tickover is now a bit on the high side even with the adjusting screw wound right back. I have also checked the screw which slightly opens the throttle when the choke is operated and it's clear of the cam.
I believe leaks in the intake can have this effect but I only removed the Carb from the adapter it all looks OK.
Before I strip it down would a high fuel level in the float chamber have this effect as with the electric pump there's obviously much greater pressure in the fuel line which I guess could affect the level.
Any suggestions would be appreciated.
John.