Questioni just bought a 1980 kawasaki KZ440 LTD. its not ran for a year, i cleaned, out the carbs and, and got it to run, it backfires off of the right cylinder, could this be due to weak or bad points. as far as i know all the jets and everything on it is stock, and possibly factory.
Answer
Hi Chris,
Backfires can be caused by a few things.
Always check compression before tuning an engine.
Main cause is a lean fuel mixture.
If the carbs were not soaked in some
good carb cleaner the passageways could
still be plugged after sitting so long.
Brass carb idle and main jets should be physically
cleaned with a small smooth wire or such.
Another cause for backfiring is any exhaust
leaks such as the gaskets near the head.
Another cause for lean fuel mixtures are
air leaks around the carb mounting rubber
or gaskets. Any air/vacuum leak can
cause a lean backfire.
This can sometimes be checked by spraying
some carb cleaner or starting fluid around
the intake area and see if the idle speeds up
indicating an air leak.
Your points should be checked
for maximum opening about .014" and firing
on the timing marks on the rotor.
They also need to be clean.
Excessive sparking on the points indicate
a bad condensor.
Lastly a sticky valve might be causing some
problems, check valve clearance, about .004"
is okay and maybe run some fresh fuel
with "Seafoam" might help.
Good luck!
Wayne S.
