QuestionI have a 1985 KD80 that I recently got running after sitting for 2 years. The problem I am facing is that the idle will just climb, until the bike is wide open. I took off the side cover to view the carb thinking the slide was sticking but it is not. My thoughts lead to vac leak but why intermittent? And why if I slip the clutch can I get the bike to idle back down (at least for a little while).
AnswerPaul,
it is likely after sitting so long that
the engine seals could be leaking air
into the crankcase. This leans out the fuel
mixture making the engine race.
-make sure the carb is clean inside and out.
-check the flange where carb goes on, make
sure it's tight.
-clean and adjust points/ignition timing.
-check that points are opening at the timing mark.
-check for at least 100 psi compression.
-it is likely the crankcase seal under the flywheel
that is leaking air.
Other possible leaks are the cylinder base gasket.
AND finally the problem that put my 67 J1T 85cc
Kawasaki out of business: a damaged rotary valve
disc.(under the covers the carb hooks up to)
Here is a web site that explains 2 stroke engine
air leaks and pressure testing:
http://www.off-road.gr/article25.html
It is intermittant because it is probably a small
air/vacuum leak that takes awhile to
lean the mixture each time you slow
it down. The seals may swell with some use
if they are not damaged, if not you will
have to replace them.
