Kz700 blows smoke when cold

Hey all - working on a 1984 KZ700 with 8700 miles. When starting in the
morning, having sat for a day, the bike will blow a lot of smoke out the
tailpipes, sometimes both pipes, sometimes one or the other. The smoke
looks bluish. I asked a local mechanic and he said that it doesn't mean
anything.
Am I staring at a mechanical nightmare in the near future? Valve stem
seals? The motor runs and sounds great once it warms up.

 

Correct. Keep the oil from carbonizing onto the intake valve stems by
mixing Techron Concentrate with your gasoline to avoid burning the
intake valves. Keep an eye on the valve clearances and listen for
spitting back through the carburetors. When the compression drops off,
do a valve job and, for that matter, re-ring the pistons.

 

i would get the seals replaced asap or as soon as you can afford it the
dealer should be able to do this without pulling the head then you can get a
valve adjustment at the same time and save some money if you dont care much
about the bike then just run it should last a few years anyway

 

Rules of thumb:
It if is black smoke, you are burning a rich fuel/air mixture.
White smoke, you are burning water.
If it is blue smoke, you are burning a bit of oil.

Blue smoke on start-up, which goes away after warm-up, is leaking
valve guide seals. (oil is seeping past the seals after the previous
run)
Continuous blue smoke, which never goes away, is compression/oil
leaking past your rings (both ways).


Given your symptoms, I'd say leaking valve guide seals. It is not a
real problem, and will be easy to fix during your next needed top end
job. Any good quality top end gasket set for 4-strokes will have valve
guide seals included.

Jim Cook
Smackover Racing
Gas Gas DE300
Team LAGNAF
www.smackovermotorsports.com

 

Be smart and check compression dry and wet. see if has valve seals or not
for that bike. you can check them when you have the valves adjusted. the
guides may be worn, leting oil in when shut off. go one step at a time. good
luck, and ride safe.