Hitchcocks Forum

Hi All

Went for a short ride this morning and, after switching off, noticed white smoke coming out of the carburetor through the air filter; carburetor and air filter still cool to touch; lasted 4 minutes or so; hope somebody has an idea about what's causing this.

Cheers

Fredo

Check the air filter, is a there is a segment at the bottom soaked in oil, it would suggest over filling with oil.

Hi Fredo, It might just be down to the position of the crank when the engine stopped, after switching off. It might have been about to fire when switched off [no spark] and rolled back a little, opening the inlet valve again by a small amount and thus producing a thick, white fog pouring out of the intake. I have seen it on occasions and it is nothing to worry about. On kickstart bikes, you can stop it by giving a nudge on the kickstart, to put the engine on compression, where the valves will be shut. regards, Paul.

Hi Paul

That seems to be what it is; thanks!

Fred

I think Paul has it there. The compression and power strokes will both will both, like an air gun, make the motor tend to stop with a valve open. The white mist may be more apparent on moist humid days.

but before walking away we all ensure the engine is left with both valves closed don't we ?

Used to happen a lot in the old days with carbs fitted with bellmouths. Sometimes you could see a swirl of white vapour coming out of and then being sucked into the bellmouths. Used to put a sink plug in my Goldie one...

Ric writes: "but before walking away we all ensure the engine is left with both valves closed don't we ?"



Completely pointless. It's only due to it being a single that we can arrange for all the valves to be closed anyway - three and four cylinder bikes always have at least one valve open, and nothing terrible happens to them.



If you are going to store it in a damp shed for fifty years, there might be an argument for it. But even then it's only a "might".

ric - (rofl) no, I can think of better things to do, like oiling the chain or making a cuppa After getting off the bike at my age first priority is probably having a pee