QuestionHi there, I recently bought this bike and put carbs on. could you tell me how to adjust the idle speed i cant seem to figure it out. There is a screw on the bottom with a black knob on it. Is this the idle changer?
AnswerHi Speedy,
The black plastic knob is used to adjust the
idle speed to about 1100 RPM.
The idle pilot screws are used to adjust
the fuel and air mixture at idle.
They are sometimes covered with a plug
so you cannot adjust them unless you
remove the plug. It may be removed
already, if so you will see a small
flat screw head on the side of the carbs.
They are about even with the top of the float bowl.
Adjust them to about 2.5 turns out and
then adjust to where the bike runs the best.
To remove the cover plugs you have to drill
a small ways into the plug but not so far
as to damage the screw head.
Then put a sheet metal screw in the
plug and pull it out. The idle mixture
screw is under there.
Also to get the bike running smoothly the
carbs should be synchronized.
This is basically using a vacuum gauge
or stick to set all the carbs at
the same throttle opening at idle.
The vacuum readings help to
set the carbs so they all close and open
at the same time.
You can do this roughly by looking at your
throttle plates and see if they are opening about
the same time. If not, they are adjusted
with the screws that you will see between
the carbs on the throttle linkages.
A set of vacuum carb sticks will make this much
easier. You can look these up online for more info.
Once the carbs are syncronized then the large black knob
can be used to lower and raise the idle on all the
carbs equally.
When adjusting the pilot mixture screws always keep the idle
as low as possible and lower it with the black knob
if the idle starts to go too high.
The mixture screws will only work at standard idle speed
and will not have any effect if the idle is too fast.
Standard idle is about 900 rpm to 1100 rpm or so.
Good luck!
Wayne S.
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