QuestionWayne – My 360 continuously stops firing on the left cylinder. We have replaced the points several times and the problem returns. Can set the points, adjust them, and it will run smooth for a short time. If I ride it for any period of time it starts to miss and finally will quit firing all together. The right cylinder is fine?
Any thoughts? -- RB
AnswerHi RB,
This can be many things so it helps
if you can isolate the problem
by checking the spark with a timing light.
Often the spark will look okay when
the spark plug is out and yet fail when
under compression.
The timing light will show you if the spark
is the problem or not. If the spark
is stopping then it might help to
swap the coils and see if the problem
switches to the other cylinder.
Another possibility is that the
point gap is too large preventing
the contacts from closing completely.
Set the point gap on the highest part of
the points cam at .014"
If the compression is low the cylinder may
not idle well. The valve clearance
should be set at .002"intake - .004" exhaust.
If the pilot fuel jets or passageways in the carb are
plugged it will not idle or speed up smoothly.
Check the plug caps for no more than 5000 ohms.
Check the points cover is not shorting out
the points.
Check for weak battery or poor connections.
Check around the carb rubber boot and the mounting
flange for vacuum air leaks.
Check carbs for missing vacuum caps.
Synchronize the idle speed screws so both cylinders
pull the same weight(speed)at idle.
Check float bowl for water/dirt.
Makes sure the misfiring cylinder has
good compression, correct fuel height
in the float bowl, clean carb and jets.
No air/vacuum leaks.
Good plug cap and coil, condensor.
Set points gap and timing.
You can sometimes switch things from the
running cylinder to the misfiring one
to see what happens. This might help
isolate the problem.
See if the fuel is flowing well from the tank
to the carb.
Clean all the wire connections and grounds
to the ignition components.
Charge the battery fully and see if that helps at all.
The final and not happy suggestion I have is
to check the camshaft for wear or "bounce"
on the points side. Sometimes if the
camshaft or camshaft bore is worn
the points can bounce preventing
proper spark action.
This is the worse case as it requires
either repair or replacement of
the head and camshaft.
There should be very little or no play
up and down etc on the points end of the camshaft.
Good luck with it!
Wayne S.
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