Reply To: Thor and Sea King poppet valves

[PM T2]

The lever sticking out front of that mixer is indeed the needle valve for adjusting the fuel mix.

With poppet valve carbs (or mixers, mixing valves, whatever you prefer to call them) the main things with the mixer is ensuring that
a) the gasket is sealing where it mounts to the crankcase
b)the threaded cap on top also provides a good seal to prevent air leaks into the poppet valve chamber,
c) the poppet valve itself is loose and not stuck to the seat,
d) the spring tension needs to be of a sufficient level that it will return the poppet valve to the close position yet allow it to lift off the seat during the intake phase, and
e) that the needle valve is not loose and flopping around and is allowing fuel to leak past it.

I would mention poppet valve lift/travel (how high it can rise off its seat) but with a Thor mixer, its not necessary because the Thor mixer has no way to adjust that amount of travel anyway.

One of the key elements in poppet valve miser operation is crankcase sealing. If the crankshaft bearings are worn and the clearances are too great, Thors are terrible for displaying behavioral problems that would make a preacher curse.

With the spark plug removed, rope the motor over and listen to the poppet valve. If it snorts or burps every time the motor turns a revolution, it should be functioning well enough to give you some hope of getting t he motor started….. assuming the magneto is working and cylinder compression is strong enough.

Hope this helps.

Best,
PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...