QuestionI have a very Hard to Start 2002 Honda XR80R & at times I can't start. It used to start like a watch! Not anymore.
I have installed a new Carburetor kit, set the Small air mix screw at 1-1/4 turns out from bottom, the Large idle screw at 2-1/4 turns out from bottom. Jets are clean, Valves are adjusted at about .003 Cold. Cam chain is in good adjustment and shows no sign of wear at cam sprocket. I have spark when checked by resting plug against cylinder and turning over the engine. Air Cleaner is clean, Compression feels normal. Engine kicks over good but not starting. I am not flooding during start. I use no choke as the temp here is in the mid 80’s to 90’s “Florida”! Occasionally I can get it running but it seems to be by chance when it stars. Often it will backfire when I persist at trying to continue to kick it over. Any thoughts on this that might help? Thanks
AnswerHi John,
When an engine backfires it usually
means it is either running lean on
fuel or has an excessive amount of air
getting into the fuel mixture somewhere.
It could also be the air gap is too large
on the ignition pulse coil or the flywheel
key has stripped and allowed the ignition
timing to change.
Try a quick shot of starting fluid in the carb
mouth to see if it will start on that.
Then check for vacuum leaks around the carb
and intake gaskets. The spray will cause the
engine speed to change if it senses a vacuum leak.
If it will start on the spray then you know
you likely have a fuel or vacuum problem.
Make sure your carb float is working
and allowing the carb bowl to fill with fuel.
Some aftermarket carb kits can be finicky
so try adjusting your idle screw out
a bit at first and try your air screw in
various settings as well.
Compression can feel okay but can often be
too low when checked with a gauge.
A leaking valve or ring can also be
a source of hard starting.
It sounds like the fuel is not being drawn
into the engine either due to
a fuel supply problem or an air/vacuum leak
on the intake.
The spark should jump a gap of about 5 millimeters
or 3/16" and a blue spark is best.
Good luck!
Wayne S.
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