Motorcycle Repair/1983 Honda Magna v45 750
Just had my bike at the Honda shop here where I live.Had carbs replaced,rebuilt,and sync.Bike runs fine,with the exception of,when you throttle up, in gear or in neutral,it doesn't throttle back down to proper idol position.You can pull in the clutch lever and it goes right to proper idol.The shop here says they don't know why its doing this.Any ideas? Thanks
The clutch is likely just creating some drag on the engine
so it settles down to idle.
The cause is one of the following:
Choke hanging up or misadjusted.
Air leaks around the intake rubber boots between the carbs and engine. Check with starting fluid, wd40 or carb cleaner spray.
If the engine speed changes then there is a air or vacuum leak.
Sticky throttle cables
Pinholes in carb slide diaphragms.
Leaking float needle valves, some seafoam might help if you run it a few days.
Carb sync off a bit or pilot idle screws need adjustment. (Under aluminum plugs on carbs, The plugs must be drilled carefully and pulled out.
The idle fuel mixture may be too lean.
Check the spark plug color, black is too rich, whitish is too lean on fuel/air.
Carb synch can be very fussy and can cause idle hangups if the idle drop is not exact. This is a common problem on early magnas.
If you have a vacuum fuel petcock they can leak fuel into the intake as well. This may be only on Sabre models.
If you run some seafoam through with premium fuel it might help over time if it is not any of the above problems.
Sticky mechanical timing advance units cause this symptom too but I am not sure if you have that as on even older Hondas.