1992 marathon with 295 cc engine using oil

[dcotton4]

A friend has a 92 marathon with the 295 cc 4 cycle engine and is starting to smoke quite a bit. Checked compression and both cylinders have around 165 psi. Is it common for the valve seals to fail on these engines? Also checked crankcase breather and it looks good. Any tips would be appreciated! Thanks Dave

[nobuckbuild]

first question is the cart lifted , if it is the dipstick will not read correctly and the oil is probably overfull

[sccowboy]

An excerpt from the service guide;

Indicates 140 psi (965 kPa) (Ref. Fig. 22 on Page
G-11). Compression is good and the engine may
be new or rebuilt. If the engine is new or rebuilt, the
compression will rise to approximately 160 psi
(1100 kPa) as the rings seat. If the engine has had
extensive use, a reading of 140 psi (965 kPa) may
indicate that the engine compression is in decline
and may need to be rebuilt when compression falls
to approximately 125 psi (860 kPa).
b) Indicates 50 - 60 psi (345 - 415 kPa). The rings are
in very bad condition or leaking valves are indicated.
Pour approximately one half ounce of thirty
weight oil into the cylinder through the spark plug
hole and recheck. If the compression increases 10
psi (70 kPa) or more the rings are in poor condition.
If little or no increase in compression is indicated,
the valves are leaking

You could try the 30 weight oil trick to check it.

[dcotton4]

Cart is not lifted and is all stock

[nobuckbuild]

then lets have an oil change first with only 1 1/2 quarts of oil and check for improvement , sometimes oil breakdown or gas saturation due to sticky float needle in the carb can cause oil to washdown and cause smoking , we first try the cheap way before tearing into heads and rings