PCV valve ?

I suspect I will be installing one to my '75 MkIII to take care of leaks. I only hope it does the trick. Thanks to everyone who has contributed to this thread.

I too have been reading all the posts on crankcase breathers. I have a 72 Combat and have not been able to find any pics of the unit itself. My bike has had mods done on it , like the anti wet sumping valve and there are lots of braided lines....
Can someone confirm that the valve is the picture is standard....?
Tricky to take a photo of as you can' really see in there very well.
The hose goes from there to the top of the oil tank.
Bike does seem to leak quite a bit, but I have been unable to pin it down.
Ideally I'd pull the motor down and do the pick up mod....but it runs so well and I already have a dismantled Beetle in the shed.... :roll:
thanks

your photo show;s the STD. combat breather. it has some parts inside to act as an oil separater. your bike is a perfect candidate for the bolt on reed kit from Jim or CNW. as for the anti wet sump valve GOOD LUCK THERE you need an oil pressure gauge to go with that BODGE!!! I am also NOT a fan of the braided steel BLING as all it is good for on the lines from the oil tank is to shorten the life of the oil tank mounting brackets and to saw through ANYTHING they touch.

72Combat said:

I too have been reading all the posts on crankcase breathers. I have a 72 Combat and have not been able to find any pics of the unit itself. My bike has had mods done on it , like the anti wet sumping valve and there are lots of braided lines....
Can someone confirm that the valve is the picture is standard....?
Tricky to take a photo of as you can' really see in there very well.
The hose goes from there to the top of the oil tank.
Bike does seem to leak quite a bit, but I have been unable to pin it down.
Ideally I'd pull the motor down and do the pick up mod....but it runs so well and I already have a dismantled Beetle in the shed.... :roll:
thanks

Click to expand...

Yep standard Combat vent baffle that works a treat as long as not holding over 6000 rpm for long, which is just short of 2S cam coming on cam. If engine is sealed well with gaskets, goop and Hi enough and repeated fastener torque, then a plain Jane $5 brake booster or more expensive $100 Krank PVC in line can keep a Combat as dry and oil tight as any. The main downside i find keeping the breather baffle is it prevents gear box removal w/o lifting the engine up/forward. Also while other Cdo's may take a few minutes to flush out parked wet sump, a Combat clears its sump in under 30 sec. d/t the pencil thick jet of oil via the breather hose instead of just spitting up trickles of the oil pump return. Only tools needed or hose cuter and maybe screw driver for hose clamps. Only my Trixie I got a few 1000 miles oil dry w/o a PCV but then I assume because of not attending to the retorque before and during 1000 mile trip, it began to weep here and there and now smokes like a oil fire out head gasket.
So PVC won't help if oil sealing already blown a path out here and there. Its hard to put the hose on down there with clamp once engine and tranny installed.

Looks to me as though the fittings leading from the breather to the stainless braided line are a bit of a bottleneck.

If you are having problems I suggest opening up the breather spigot diameter to where it should be,.... and fitting a larger rubber hose.

This is a quick and easy test.

Once again, thanks all for your input. Can the PCV valve be fitted to the motor as is or does the mods to the case to stop the oil backing up done first?
The PO ( who'd be that guy) was an aircraft engineer for the RNZAF and seemed to like braided hoses....they are all thru the oil system....I don't like them as stray braids hurt like hell.
PO also fitted an oil pressure guage, goes right up when it cold and sits on around 20 psi running over 50 mph...at around 20 to 25 degrees C.....more it its colder.
I find it reassuring......don't know why as my bevel drive Ducati has only a speedo and tacho.....oh I do know, there are no forums to make you worry about every moving part :lol:

like I stated CNW and Jim Comstock on here sell a REALLY nice bolt on read valve breather for your engine. as to the case mods unless you go out and run it at or near redline all the time it is not a have to do. the ONLY place I like the braided steel line is on the rocker feed. do your self and the bike a favor and change the others to a good quality rubber line.

72Combat said:

Once again, thanks all for your input. Can the PCV valve be fitted to the motor as is or does the mods to the case to stop the oil backing up done first?
The PO ( who'd be that guy) was an aircraft engineer for the RNZAF and seemed to like braided hoses....they are all thru the oil system....I don't like them as stray braids hurt like hell.
PO also fitted an oil pressure guage, goes right up when it cold and sits on around 20 psi running over 50 mph...at around 20 to 25 degrees C.....more it its colder.
I find it reassuring......don't know why as my bevel drive Ducati has only a speedo and tacho.....oh I do know, there are no forums to make you worry about every moving part :lol:

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72Combat, you can go cheap and simple with PVC stuck inline with the breather hose to oil tank or expensive and involved with the reed valves mounted to cases, but unless something rather wrong with your engine, they all work to solve oil pushing out. IF something rather wrong with an engine the check valves won't help much if at all. The better valves work better over 7000 is all. Norton should of supplied Cdo's with them. Might work better mounted closer to engine we've learned but I've learned they still work good enough mounted up out of sight close to oil tank.

bill said:

like I stated CNW and Jim Comstock on here sell a REALLY nice bolt on read valve breather for your engine. as to the case mods unless you go out and run it at or near redline all the time it is not a have to do. the ONLY place I like the braided steel line is on the rocker feed. do your self and the bike a favor and change the others to a good quality rubber line.

Click to expand...

Cheers Bill, I had to Google those names but wow they have some nice parts, as you say its a bolt on job and no I tend not to take these old machines to redline....I have a track bike for thrashing. Swapping out the braided lines is a bit tricky as PO has welded/brazed on all the fittings..... :roll: