Oil Decompression/Catch Can

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hookedonit
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Oil Decompression/Catch Can

Post by hookedonit »

Anyone have experience with an Oil Catch-Can on a PCX150?
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Re: Oil Decompression/Catch Can

Post by springer1 »

I haven't in my PCX, but had to 'back when' on my 1970 Norton. The Norton is a dry sump engine with a seriously tight crankcase, with pressure issue potential because (like all vintage Brit twins) the twin pistons rose & fell together. So, I made an oil separator to fit between the PVC and the Carbs' Airbox ..... with the outlet tube that (hopefully) vented a good portion of the separated oil terminating just above the final drive chain .... sorta like an automatic chain oiler.

I understand that some Commando models had some sort of similar arrangement from the factory but I've never actually seen one in person. I made mine to try and help keep the Airbox, Air filter and Carbs a bit less fouled from oil .... it worked "ok" but not great. My separator's design wasn't exactly lab tested & high-tech LoL.

I did assist a fellow Norton rider once on the way the the annual "Butler's Orchard" swap meet in MD. when his (either factory or homemade) design resulted in oil being misted & spewed all over the rear of his bike & girlfriend. I simply gave him a quart of oil to replace what was lost, I have no idea what was causing his PVC from spewing so much oil.
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Re: Oil Decompression/Catch Can

Post by hookedonit »

Added one but instead of attaching to the oil intake, I attached it to the crankcase vent.
Prefer this over the drippings going back into the airbox on the OEM design.
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Re: Oil Decompression/Catch Can

Post by hookedonit »

My YSS shocks are on on a boat... a very slow boat.. for anyone that spots the sticker. :lol: 8) :roll:
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Re: Oil Decompression/Catch Can

Post by springer1 »

Interesting! .... what is that it terminates to, is that a small muffler of some sort? .... and is there some sort of valve to prevent back flow?

Thanks !
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Re: Oil Decompression/Catch Can

Post by hookedonit »

springer1 wrote:Interesting! .... what is that it terminates to, is that a small muffler of some sort? .... and is there some sort of valve to prevent back flow?

Thanks !
That is just a catch-can. This one is a small chamber, no meshing, but some come with meshing, and multiple intakes so you can attach it directly to where your oil dipstick would be.
Some have airfilters on them.. Since I'm only using it to catch the oil that get spit out from the crankcase, no real back flow concern.

If you have your stock OEM airbox; on the backside is a tube that connects to the crankcase vent. This drips oil into the airbox (behind the filter) so its consumed back into the engine.

A second aspect of the of this catch-can is meant to catch that oil (if connected to the oil intake) on high RPM (decompression). And when in low RPM the oil could drain back into the crank case. <- thats what I've read at least haha.
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Re: Oil Decompression/Catch Can

Post by springer1 »

hookedonit wrote:
springer1 wrote:Interesting! .... what is that it terminates to, is that a small muffler of some sort? .... and is there some sort of valve to prevent back flow?

Thanks !
That is just a catch-can. This one is a small chamber, no meshing, but some come with meshing, and multiple intakes so you can attach it directly to where your oil dipstick would be.
Some have airfilters on them.. Since I'm only using it to catch the oil that get spit out from the crankcase, no real back flow concern.

If you have your stock OEM airbox; on the backside is a tube that connects to the crankcase vent. This drips oil into the airbox (behind the filter) so its consumed back into the engine.

A second aspect of the of this catch-can is meant to catch that oil (if connected to the oil intake) on high RPM (decompression). And when in low RPM the oil could drain back into the crank case. <- thats what I've read at least haha.
OK, understood .... my small brain needs to think about this a bit. The "Catch-Can" I had made was really an air-oil separator (via baffles) which had it's intake from the crankcase PCV valve. The bulk of it's output (upper) still went to between the air filter and carbs to be ingested by the engine. But it also had a smaller lower output that allowed any separated oil to drain out and via small hose drip onto drive chain. LoL, it probably was at best 50% effective if that.

But, it never defeated the PCV function by circulating pressure back directly into the crankcase either. I suspect these newer setups are dealing with very different issues and solutions - and are pretty well thought out.
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Re: Oil Decompression/Catch Can

Post by easyrider »

Catch can myth.. In very high compression engines a catch can may have some benefits in short term longevity. However if you want your engine to last a long time I would not use a catch can. The return blow by gasses contains light oil mixture (mist) that's returned to the upper cylinder walls and the valve stems and guides. This return mist is essential in providing a light lubricating film to the pistons and valves upper cylinder thus giving you a better compression seal with the rings. Used in high compression situations ie racing environments this will have some value because the blow by is excessive. If you really want to keep your engine a long time keep your oil changed frequently and use an upper cylinder detergent every 5000 miles. Todays' gasolines have good detergents but I like Chevron Techron the best. Using a good detergent fuel , and frequent oil changes is key to longevity.. Keep in mind manufacturers like to sell parts , but you don't see them on cars for a reason, unless they are high performance exotic breeds, because they don't usually acquire high mileages.
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Re: Oil Decompression/Catch Can

Post by hookedonit »

easyrider wrote:Catch can myth.. In very high compression engines a catch can may have some benefits in short term longevity. However if you want your engine to last a long time I would not use a catch can. The return blow by gasses contains light oil mixture (mist) that's returned to the upper cylinder walls and the valve stems and guides. This return mist is essential in providing a light lubricating film to the pistons and valves upper cylinder thus giving you a better compression seal with the rings. Used in high compression situations ie racing environments this will have some value because the blow by is excessive. If you really want to keep your engine a long time keep your oil changed frequently and use an upper cylinder detergent every 5000 miles. Todays' gasolines have good detergents but I like Chevron Techron the best. Using a good detergent fuel , and frequent oil changes is key to longevity.. Keep in mind manufacturers like to sell parts , but you don't see them on cars for a reason, unless they are high performance exotic breeds, because they don't usually acquire high mileages.
But it looks faster! :lol:
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