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Discussion Starter · #1 ·
So I ordered a crankcase cover for a 1973 cb350g that has fittings tapped into the case where the centrifugal oil filter is and has a external replaceable filter - I'm wondering if the oil pump puts out enough pressure to not hinder my oiling and pile up my motor - i've got it bored over and high compression pistons and really don't wanna pile it up but I also thought it would help take out the fine metal from the oil any help with this would be appreciated
 

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Not really any help but is it a custom made cover? Pictures? Just curious.
 

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Usually the tapped cases are a oil cooler provision. Good frequently changed oil is probably better that overheating. I hear capallini overbores the pump but can't confirm how much.
 

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Discussion Starter · #6 ·
Still waiting for the cover to come in the mail - fingers crossed it works for me and doesn't pile her up
 

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Cappellini indeed enlarges the oil pump bore but only marginally. Just enough to make it perfectly round. He used used pumps as the basis. I think it was .3mm.

By the way:i have a Cappellini paper filter conversion on my 350. Works fine and has been working fine for over three years now. Oil comes out cleaner and less debris in your engine case. Also works better in combination with synthetic oils where the oil slinger loses (part) of it's function due to the detergents in the oil that cause the particles to stay afloat instead of clogging together.
 

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Capellini also makes a kit to upgrade the oil pump and swap out the original plunger type pump for a modern rotary pump.

stock pumps can’t keep up if you build a motor and spin it at high rpm for extended periods.

The plungers begin to cavitate and froth the oil...which wipes out the cam in about 10 minutes
 

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Capellini also makes a kit to upgrade the oil pump and swap out the original plunger type pump for a modern rotary pump.

stock pumps can’t keep up if you build a motor and spin it at high rpm for extended periods.

The plungers begin to cavitate and froth the oil...which wipes out the cam in about 10 minutes
How many rpm are we talking for this kind of thing?

I have never heard of cavitation in positive displacement systems before... centrifugal pumps are quite prone to it.

Sent from my SM-G930V using Tapatalk
 

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I think it's more the extended amount of time as much as the rev range, but when road racing or running flat track you'd be in the upper half of the rev range most of the time and it can definitely happen
 

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I encountered this on several race bikes

We regularly spin to 11,000+ RPMs I’m not certain where it starts though but suspect it begins mid 9ks
 

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I encountered this on several race bikes

We regularly spin to 11,000+ RPMs I’m not certain where it starts though but suspect it begins mid 9ks
Sorry to jack ...

How do you know it's cavitation, and not starvation due to more oil up in the head?

...that was a classic problem with the corvettes before they introduced the deep sump system. ...the linear pump curve of the piston pump means more oil in the system and less in the basin as rpm's increase... eventually starving the pan.

The centrifugal pump does not pump more oil linearly as velocity increases... so the oil that is flowing through the heads and other areas is more consistent regardless of how high the RPMs go...


As for the possibility of a cavitation... is it happening at the inlet to the oil piston? Is tyere evidence of sheer breakdown, or foaming?

Not trying to thread jack, I'm an engineer who does pump design for wastewater, so this is of deep interest to me... the primary reason i chose this bike was for the positive displacement oil system.
 

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I’m not an engineer

was told it was cavitation by several engine builders many years ago and had no reason to question them.

yes there was frothed oil. The return path of oil from the head is open and Unencumbered

rotary pumps installed on the race bikes never lost the cam bearings again so I never tried to analyze further
 

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I’m not an engineer

was told it was cavitation by several engine builders many years ago and had no reason to question them.

yes there was frothed oil. The return path of oil from the head is open and Unencumbered

rotary pumps installed on the race bikes never lost the cam bearings again so I never tried to analyze further
I really appreciate your experience and reply.

Sent from my SM-G930V using Tapatalk
 

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For a normal streetbike with a (semi) standard cam the standard pump works ok. On the road I rarely go past 9k. If your bike is seriously tuned and you constantly ride it close to the redline: use an eaton pump
 

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Stock centrifugal filter is more efficient at removing particulate than any paper filter which only really filters to about 30 micron. (even 10 micron filters 'allow' about 10% through)
The only 'advantage' I see is modified oil transfer piece in clutch cover or external oil lines to cam
 
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