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V50/V35 Gear box seeps oil through top vent

The parts breakdown doesn't show any valve stem seals for this bike. Maybe disassembly will show otherwise?
 
So, having two "stem sealed" heads on a ridden 1979 bike, I have taken a head off spare 1980 engine. What I have found?
IMG 20210313 132546
Now, if this is a home made improvement, the grove machined on the valve guide is there exactly to keep the seal in place, what means, must have been done first and then pressed in. IMG 20210313 133315
The seals are CORTECO B15 V4-161, for 5.5 valve stem, 9mm guide diameter, 8.5mm high.
Hey John, we learn something new every day, don't we?
 
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Those seals aren't factory. They were added by someone. Some oil in the guide is good for lubrication. The K-lines have grooves to hold oil to lubricate the valve stem.
 
Those seals aren't factory. They were added by someone. Some oil in the guide is good for lubrication. The K-lines have grooves to hold oil to lubricate the valve stem.
Could be. But then an entire idea of stem seal would be wrong, as how to maintain oil presence in the guide if seal does what it says on the label. Then, with 66kmiles on the clock, I find my engine healthy enough to pull sidecar with no trouble. So, lack of oil in the guide isn't that lethal.
You've mentioned "K-lines" several times, would you tell me what does it mean. Never heard of it before.

Oh, I have dug a bit more in my spares, some of them new old stock, bought as a job lot years ago. I knew I could have another part of the puzzle: Valve guidesV50
 
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K-lines are valve guide "liners". See the installation video from SB, Intl:



It takes some special equipment to install them.

Maybe Guzzi went away from valve stem seals by 1979/80? Maybe the guides had grooves but they were using generic part sourcing and never needed or used the grooves? I'm taking my heads to a machine shop on Friday. I'll get them to check to see if my valve guides have grooves for stem seals.
 
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Photos from head removal. The left head was not fully torqued down I discovered but the gasket was in good shape. The right side didn't have any loose bolts but the gasket may have been having an issue. A more seasoned eye might be able to make something from these photos.

With due double valve spring setup (inner + outer) it doesn't appear there's any room in there for valve stem seals.
 

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With due double valve spring setup (inner + outer) it doesn't appear there's any room in there for valve stem seals.
I can assure you, the room is there:) I gave you seal measurements, just check ID of inner spring.
 
I can assure you, the room is there:) I gave you seal measurements, just check ID of inner spring.
These are standard to all V35-V75. GU19037820, replaces 61037801. Search and you'll find them on Gutsibits, Stein-Dinse, Harpers etc.
 
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These are standard to all V35-V75. GU19037820, replaces 61037801. Search and you'll find them on Gutsibits, Stein-Dinse, Harpers etc.
I'm not familiar with Gutsibits or Stein-Dinse. Which would you suggest for someone on the West Coast (USA)? I'm done with Harpers if there's an alternative...
 
I can assure you, the room is there:) I gave you seal measurements, just check ID of inner spring.
You are correct, there is room. The machinist at the shop said my heads did have stem seal (and they need to be replaced). Worn exhaust valve guides as well...
 
These are standard to all V35-V75. GU19037820, replaces 61037801. Search and you'll find them on Gutsibits, Stein-Dinse, Harpers etc.

The heads came back from the machine shop looking like new: resurfaced, valve job, and new stem seals/valve guides courtesy of MG Cycle. The machinist did say the heads did have stem seals installed. I have no idea if they were original or not. With 32k miles its hard to say. I have a good feeling this will fix my oil fouling problem, but unfortunately I broke my hand and won't be able to do any wrenching for a few months. I'll check back in after I've got her back on the road...

p.s. I paid $525 for the head/valve work described above and I had to source my own parts. That was a bit more than I was expecting, plus it took 2 months. The shop said they don't work on mc heads often, but it seems like they did good work. Is this a typical price for valve work and resurfacing?

IMG 1808
 
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