Author Topic: Venting tappet covers?  (Read 4410 times)

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Offline PeWe

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Re: Venting tappet covers?
« Reply #25 on: March 03, 2019, 07:43:07 AM »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline slikwilli420

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Re: Venting tappet covers?
« Reply #26 on: March 03, 2019, 09:14:55 AM »
Valve for valve cover breather. How will that help?
http://www.yamiya750.com/index.php?main_page=product_info&cPath=246_21_249_49&products_id=3974


Looks like a pcv valve. Can be had for a few dollars at an auto parts store.
All you gotta do is do what you gotta do.

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Offline Cb750 Racer

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Re: Venting tappet covers?
« Reply #27 on: March 03, 2019, 05:25:20 PM »
Valve for valve cover breather. How will that help?
http://www.yamiya750.com/index.php?main_page=product_info&cPath=246_21_249_49&products_id=3974
I think the worry with these venting covers is oil flinging off the valve/retainer and not falling back down as it would with the stock caps. This problem is really dependant on which caps you switch and the way the hose is routed off the vented caps. A valve right above the vent would definitely help. But then again when the pressures high enough to open the valve oil will be flinging out regardless. Not really sure where to stand on that debate but I think a fine screen above the vented ca would be the best solution IMO.
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Offline Bill/BentON Racing

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Re: Venting tappet covers?
« Reply #28 on: March 04, 2019, 07:55:05 AM »
Yes, clutch cover works well.
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Offline PeWe

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Re: Venting tappet covers?
« Reply #29 on: March 04, 2019, 10:14:49 AM »
Yes, clutch cover works well.
I have had years of small oil weep between cases at front due to no knowledge of this simple modification.
Plus more recent problems when testing additional vent via the rear hose to oil tank and even more with an earlier oil tank.... most oil just disappeared, rear end rust protected ;D

That little vent thru clutch cover fixed it alone, even with 71.25mm pistons. 836 on a street bike need this vent too, at least mine. Business for shops selling covers with welded hose connection.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline scottly

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Re: Venting tappet covers?
« Reply #30 on: March 04, 2019, 06:30:58 PM »

That little vent thru clutch cover fixed it alone, even with 71.25mm pistons. 836 on a street bike need this vent too, at least mine.
I have found no need for additional venting on my 836 with a K1 oil tank, with properly routed hoses?
Don't fix it if it ain't broke!
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Offline PeWe

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Re: Venting tappet covers?
« Reply #31 on: March 05, 2019, 02:56:06 AM »
My 836 got minor oil weeps around cases during holidays thru Germany, Austria and finally Italy. Another year via Germany, France to Spain. All day long on highway in speeds around 100mph or more helped oil to creap out.
Even shorter trips but still higher rpms most of the time ended up in dirty cases. I blamed the Hylomar blue sealer back then and years after.

It became more visual and quicker when bike got billet block with 1005cc 2017. Inspired riding often passing 8000 rpm showed weeps after around 50-100km.
This is completely fixed with the clutch vent and stock K6 oil tank without extra plumbing ;)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967