Topic: Excessive smoke in air box?

[dave400]

I’ve never run my engine with no air filter fitted, but today I started the engine after it had been standing since August 08 and took out the air filter to clean it and was surprised at the amount  of smoke from the engine breather recycle filter in the air box.. Does it look excessive? Anybody run the engine and looked in the air filer box and seen anything like the photo? Bike is a 400F.

Cheers

[Steve F]

Kinda looks to me to be unburned air/fuel making it's way backward after you shut the engine off.  Sometimes the engine will kick backward when shut down.  I'll especially notice this when I hear the starter motor spin as a result of backward turning when shutting down.  (this is on a 750)

[TwoTired]

The picture was taken while  the engine was running?

Is that white smoke/vapor?  Or blue?

The crankcase condenses out water inside the engine from repeated cooling cycles.  Heat vaporizes this water to foam a vapor cloud.  The bottom of the air filter box should have a crankcase breather connection, so that engine vapors and unburned hydrocarbon are burned within the cylinder, rather than find their way into the lungs of mammals on this planet.

Depending on how much water is in your crankcase, the vapor should clear after 15-20 minutes of operation at full temperature.

If the engine is stopped in that picture, then atomized fuel/air mixture may well back flush back through the carbs.  Particularly if the cylinder head is warmer than the air box.  Gases heating near the cylinder head would be expanding, pushing the air/fuel mass toward the colder area.

Cheers,

[dave400]

The picture was taken while  the engine was running?

Is that white smoke/vapor?  Or blue?

The crankcase condenses out water inside the engine from repeated cooling cycles.  Heat vaporizes this water to foam a vapor cloud.  The bottom of the air filter box should have a crankcase breather connection, so that engine vapors and unburned hydrocarbon are burned within the cylinder, rather than find their way into the lungs of mammals on this planet.

Depending on how much water is in your crankcase, the vapor should clear after 15-20 minutes of operation at full temperature.

If the engine is stopped in that picture, then atomized fuel/air mixture may well back flush back through the carbs.  Particularly if the cylinder head is warmer than the air box.  Gases heating near the cylinder head would be expanding, pushing the air/fuel mass toward the colder area.

Cheers,

Thanks for the replies, the engine was running in the photo and the vapour/smoke was white and getting sucked into the carbs as it should. The engine has not been run for about 6 months, condensation evaporating from inside the engine sounds good to me (I’ll be changing the oil before I use the bike), it’s been cold for the past few weeks here and my garage has no heating.

Cheers TT