Originally Posted by varmato

Honestly the manual from Saito kinda sucks on their engines and it leaves a couple of obvious things out for those new to four strokes like myself. The break in description is good, but what each screw/part does is not entirely described, hence my original question.

http://saito-engines.info is much better than the manual.

Originally Posted by varmato

So then is then crankcase vent the same as what pumps ask you to tap into a 2 stroke backplate, like the Perry pump design? In other words - hooking up a Perry pump is a no brainer with a Saito given that it already has the tap? Do OS 4 strokes have this vent as well?

Yes OS has them too. look here on page 8.
http://www.osengines.com/manuals/fs-26s-40s-manual.pdf

Two strokes use the vaccuum of the case to suck fuel and air into the chamber. They perry pumps use the positive and negative pressure bursts to run a piston and provide further pressurization.

I have never used a third party pump on a 4 stroke. But OS and YS both use them on production engines with great success.

Mike

On the OS FS70II and FS91II the crankcase vent is connected via a tubing to a nipple on the intake manifold, so all the "mess" goes back into the engine. In fact it's sucked thus improving engine lubrication.

The HP VT series four-strokes have an even more interesting lubrication system. They have a nipple on the muffler which is used to trap and route oil from exhaust into the moving bits in the head.

Because this engine's top-end is reliant on this oil for proper lubrication, you have to use castor oil -- synthetic simply burns up and produces no exhaust residue.

It's a cunning idea and seems to work very well. I've got quite a few hours on my VT21 now and desite the fact that it's a rotary-valve engine, there's no wear to speak of in the head area.

If you hook a perry pump to the oil drain nipple , the oil will have no were to go, it will build up , first slowing the motor and makeing starting difficult.
the oil needs to drain!!!
Stewart