140L or 140FZ? - External Difference?
 

I've got an engine I bought from a fellow that was sold as a 140L. It has the box and paperwork of an L, but I was under the impression that all 140L's have the rear of the engine set up with the ability to mount the YS soft mount on it. This engine does not which leads me to believe that it might be an FZ. Is there a definite way to determine the true identity of this engine with no doubts? Either way, it's a great engine, but I'd still like to know what I've got!

140L or 140FZ? - External Difference?
 

Does it have 2 fuel line fittings at the bottom of the backplate? The plumbing on the L is completely different than the FZ. FZ has no fittings on the BP.

140L or 140FZ? - External Difference?
 

Yes, the engine has the two fittings at the bottom of the backplate, one of which runs up to the front of the engine. I'm assuming this means it is a 140L, just without the mounts for the softmount?

140L or 140FZ? - External Difference?
 

It's an early L.

Good Flying,
Dave

140L or 140FZ? - External Difference?
 

Thanks again Dave!

140L or 140FZ? - External Difference?
 

I would pull the carb/backplate off the engine and look at the back of the crankshaft. If the back of the crank is a full circle and you cannot see the main bearing, it is an L. If the sides of the crank web are open and you can see the bearing, it is an FZ. The L crankshaft has a fully circular web with a groove machined into it. A steel ring, much like a piston ring, fits in this groove and seals the rear of the crank. This reduces the volume under the piston and raises the boost pressure, resulting in more power compared to the FZ.