Reed valves

rpatton said:

pelican said:

on my mk3 i cut the breather tube flush then put a bolt in the breather tube and filled it with jb weld to seal it then I screwed it back in. That way it's not a permanent seal and can revert to stock if needed.

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That's basically what I did too. I can't wait till some Norton wonk starts picking my bike apart and comes across the blocked breather...

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Just tell him you have some of those new zero blowby piston rings.

I've been trying to dig up where I read about one of the benefits of being able to generate a good crankcase vacuum. It's either Grumpy Jenkins or Smokey Yunick, can't find it. It said that the oil control package works by creating a low pressure area between the oil rings through all those little holes in the piston. It's driven by crankcase vacuum so the more vacuum the better it works. The oil doesn't get scraped off the cylinder walls so much as it gets vacuumed off. The point of the article was that if you are able to run enough vacuum you can go with low tension oil rings and unleash vast amounts of free horsepower from the reduced friction losses, and still have adequate oil control. Is it possible?

I have read some stuff about it also , probably Yunick. On my last racebike I used 1 mm rings and used an oil ring expander from a .020 smaller ring set. It sure made the pistons slide easily in the cylinders and I didn't have any problems with oil smoke. I was running a vane type vacuum pump.

Its established that combustion pressure getting behind the top ring is main force that seals pressure most from blow by. Some drlll a ring of holes around piston crown to vent combustion pressure behind the top ring to help even more. If no blow by pressure on bore side of oil ring then low crank case pressure won't help oil return by scrapping action. Some drill behind oil ring to lead oil scrapped off to the wrist pins. If top ring sealing well no need for oil ring at all i've read.
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