1198 Virago 535 10k - Smolking on start up

 

Yam Virago DX535 1998 with 10,000 miles.

Went to run the bike after laying up  for the winter and not having used for
about 6 weeks.  Bike started fine but I got a lot (like clouds of the stuff)
of whitish smoke coming from the exhaust for about a minute after starting.

The smoke is there whether I have the choke on or not although much worse if
I dont turn the choke off fairly smartly.   The smoke is whitish rather than
dark dirty colour as if it is burning oil and it clears itself after about a
minute.  Once gone (about 1 minute) it does not reappear and the bike seems
to run normally and problem is not there when I restart the bike after
having given it a run out.  If I leave the bike for a couple of days the
same symptoms re-occur.

A real pain this and I had not noticed any smoke when I was using the bike
in warmer weather.  I don't think it is water type condensation smoke (air
cooled engine) because the bike is stored in a heated garage and never
really gets cold at all.

Anybody any ideas.

Many thanks

Andy

 



Andy, from the symptoms you provide it sounds like the engine is
accumulating oil deposits in the combustion chamber over a period of
time (a few days rather than hours.)  The only thing I can think of that
could cause those symptoms would be a worn valve stem seal which would
allow oil from the head to leak down the valve stems, into the
combustion chamber very slowly.  I'm sure it continues leaking while the
engine is running but it probably burns itself clean so that it is not
noticeable.  Either that or as the engine warms up, tolerances tighten
and may reduce the rate of leakage.

You might try turning the engine over a few times, after a period of
storage, without the ignition on (to spread any oil in the combustion
chamber around) and then pull out the plugs for inspection.  If there is
oil in your combustion chamber it should show on the plugs.

If this is the problem, you are probable looking at pulling the heads,
doing a valve job (might as well check them while you have the head off)
and replacing the valve stem seals.

BMW boxters suffer from similar problems (a puff of blue smoke when you
first start them after a while of siting) from a similar problem (oil
leaking into the combustions chamber while sitting.

If it is not affecting the performance of the bike and the engine
compression is up, I'm not sure that I would invest the time and trouble
to replace the valve stem seals unless there were other work necessary.

If you wish to confirm that it is oil that is burning off, place a
hankerchief (cleanex) over the exhaust pipes when you start the bike.  
The smudge on the cleanex should confirm oil.  I can't think of anything
else it would be.  This and the plug inspection should help you identify
whether this is a problem in both cylinders or whether it is specific to
one only.

Good luck.

Ride safe.
Serge

 



You have already gotten some good advice but I gotta throw in my nickels
worth too.
You may have some accumulation around the drain areas of the top of the head
which causes oil to pool and run down your 'used' stem seals. Had a similar
problem myself years ago on a 4 stroke outboard that was cut down to
virtually no smoke simply by taking off the covers and carefully cleaning
the top end of all sludge and varnish. If it doesn't pond up it can't leak
down the stems.
Best wishes!

 



similar

That's a good pragmatic tip.