- Joined
- Jul 8, 2007
- Messages
- 10
I've searched the forums and the articles, but haven't found this issue addressed. My bike is a 73 850 Roadster, the carb internal parts (inspected and replaced as required) are in good working order, the Boyer timing is 31 by the strobe, 1/8" slack in all throttle/choke cables, the bike starts easily and will idle nicely if I hold the throttle open slightly.
My question is about exactly what controls the actual hands-off throttle-closed idle speed. Getting directly to the point, at idle should the slides be held open by the throttle screws or should the slides be held open by the throttle cables? I'm thinking it should be the throttle screws, and the throttle cables should still have some small amount of slack in them for use in synchronizing.
What I find is that if the throttle screws are backed out until only the o-ring keeps them from falling out on the ground (no threads on the screws engage with the threads in the body), that I can set an acceptable idle speed between 500-1000 rpm. This unfortunately results in no slack in the throttle cable, as I have to screw the cable adjusters in/out to regulate the idle speed plus synchronize the two carbs. I'm confident that this is not the correct approach as the throttle screws are effectively not used at all and there is no slack in the throttle cables.
Alternatively, if I screw in the throttle screws to where the screws engage the threads in the body even by a 1/2 turn (roughly 6 1/2 turns out), although this still leaves me with slack in the throttle cables for synchronizing, the idle speed is not less than 2000 rpm to 2500 rpm. When the throttle screws are turned out until they don't engage the threads in the body, the filter side of the slide (cutaway side) is open about 3/16". When the throttle screws are turned in until the threads *just* engage, this gap is about 5/16" which could explain the higher idle speed.
I'm tempted to conclude that the throttle screws are too long, except they are stock (as are the rest of the carb parts), so clearly I must be doing something wrong.
Any suggestions would be very much appreciated!
Best regards,
Ken
San Jose, California
My question is about exactly what controls the actual hands-off throttle-closed idle speed. Getting directly to the point, at idle should the slides be held open by the throttle screws or should the slides be held open by the throttle cables? I'm thinking it should be the throttle screws, and the throttle cables should still have some small amount of slack in them for use in synchronizing.
What I find is that if the throttle screws are backed out until only the o-ring keeps them from falling out on the ground (no threads on the screws engage with the threads in the body), that I can set an acceptable idle speed between 500-1000 rpm. This unfortunately results in no slack in the throttle cable, as I have to screw the cable adjusters in/out to regulate the idle speed plus synchronize the two carbs. I'm confident that this is not the correct approach as the throttle screws are effectively not used at all and there is no slack in the throttle cables.
Alternatively, if I screw in the throttle screws to where the screws engage the threads in the body even by a 1/2 turn (roughly 6 1/2 turns out), although this still leaves me with slack in the throttle cables for synchronizing, the idle speed is not less than 2000 rpm to 2500 rpm. When the throttle screws are turned out until they don't engage the threads in the body, the filter side of the slide (cutaway side) is open about 3/16". When the throttle screws are turned in until the threads *just* engage, this gap is about 5/16" which could explain the higher idle speed.
I'm tempted to conclude that the throttle screws are too long, except they are stock (as are the rest of the carb parts), so clearly I must be doing something wrong.
Any suggestions would be very much appreciated!
Best regards,
Ken
San Jose, California