Here's something else that might be worth trying if you have a leaky seal....
Yamaha used both a gasket and an o-ring on the housings. Considering all the fastener holes are blind holes, it's a somewhat unusual arrangement. Normally on a setup such as this, you'd use a gasket or an o-ring... but not both. If you were to remove the gasket and just use the o-ring, this would move the seal lip in by the thickness of the gasket. That ain't much... but it might just be enough to get it off the worn part of the cam and onto a cleaner sealing surface. Considering it won't cost anything... might be worth a shot. :shrug:
EDIT: You would first need to measure the flange on the housings and make sure there's enough room from the face to the cam bearing so you're not side loading the bearing (not pushing against the outer race).
 
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Here's something else that might be worth trying if you have a leaky seal....
That's what my earlier post #3248 was about, Jim. I tried this already on the side that is leaking and it didn't help. It may work for others depending on the condition of the end of the cam and how finished the surface is. No amount of polishing seemed to help on mine. Seriously considering the speedi sleeve approach suggested by Ozboy.
 
That's what my earlier post #3248 was about, Jim.
Doh... yeah, guess I read it and didn't register for some reason... oops. :doh:

Been looking all morning for that size sleeve. No joy so far.
 
I see Timken also makes SS sleeves called Redi-sleeve. Might be another option. Researching myself.....
 
I am also intrigued by the speedi sleeve option. I think I found the right one. It says the seal surface width is 8mm.
Is there room on the shaft for that? And another question. Should the shoulder of the speedi sleeve be removed after install. I’ve watched several install videos on YouTube, some leave it on , others peel it off. Any way you look at it , it’s not an inexpensive fix. Speedi sleeve plus new seal.
DBD6C06E-B17B-4F71-8719-117DA2FD16A8.png
 
I have been thinking about this camshaft seal leak issue that keeps coming up and a solution from back in my dark past when I was a hydraulics specialist has occurred to me. Most hydraulic motors and pumps (especially axial piston units) have a seal drain to relieve the main shaft seals from having to deal with full system pressure. The seal drain is just a little hole that vents oil back to the tank at atmospheric pressure to prevent it from leaking out of the machine.

The oil inside the XS650 cylinder head is essentially at atmospheric pressure and so the only reason for it to leak is that the cam bearings in our XS650s must be "pumping" the oil at the camshaft seals. That pumping action must be building up a higher pressure on the inboard side of the seal and that contributes to this persistent leak problem which so many people seem to experience.

I wonder if a small hole could be drilled between the outboard cam bearing and the camshaft seal that would allow oil to drain from behind the seal back into the main body of the cylinder head. The hole could be very small (1/16" dia. or so I'd say).

The other way to go at it would be to simply make a little "trough" in the bottom of the pocket in which the cam seal and bearings are installed - starting just inboard of the seal and leading back to the interior of the cylinder head rocker cavity. Again, the trough could be very small - say 0.060" wide and 0.030" deep (around 1.5mm x 0.75mm or so). That would have no measurable effect on the structural support of the cam bearings but it might relieve the pressure of their pumping action.

That would ensure that any oil pumped onto the inside face of the cam seal had somewhere to go at atmospheric pressure - other than through the seal into the LHS breaker points or RHS advancer covers from where it leaks out all over the outside of the engine - spoiling the pristine appearance of Mailman's bike.

Anyhow - I haven't been inside one of these heads for a couple of years so this idea may be all-wet, but perhaps someone who has a cylinder head apart could take a look at it and see if such a seal drain might be feasible. If it didn't work, the hole or "trough" could simply be sealed up again with JB Weld and no harm done.

A sketch of what I have in mind is attached as a .pdf and I also took a photo of it (see below).
Cam_Seal_Oil-Drain - PRF_13-04-2020.jpg
 

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I have been thinking about this and back in my dark past, I was a hydraulics specialist. Most hydraulic motors and pumps (especially axial piston units) have a seal drain to relieve the main shaft seals from having to deal with full system pressure.

It seems to me that the cam bearings in our XS650s must be "pumping" oil at the camshaft seals and that is one contributor to this persistent leak problem which so many people seem to experience. I wonder if a small hole could be drilled between the outboard cam bearing and the camshaft seal that would allow oil to drain from behind the seal back into the main body of the cylinder head. A sketch of what I have in mind is attached as a .pdf and I also took a photo of it (see below).
View attachment 164259
I like it, Peter !
Quick, apply for a patent.....
 
Ahhh... the ubiquitous "cavity drain." I suppose if someone had an engine apart, it wouldn't hurt anything to drill 'em. I just don't see how a roller bearing could be pumping that much oil (or oil pressure) in there. A typical garloc seal such as these are regularly used to hold back upwards of a hundred psi.
 
Ahhh... the ubiquitous "cavity drain." I suppose if someone had an engine apart, it wouldn't hurt anything to drill 'em. I just don't see how a roller bearing could be pumping that much oil (or oil pressure) in there. A typical garloc seal such as these are regularly used to hold back upwards of a hundred psi.

True Jim - but the point is that those camshaft seals are about the only thing on these engines that persistently leak (as long as the output sprocket nut is tight) - and so SOMETHING is promoting that leak and all I can think of is the pumping action of the double set of ball bearings.

Maybe the fit of the camshaft on the seals is wrong - or maybe the surface finish is poor......
 
Yeah, that's not cheap. My 2 24mm seals were 10 bucks to my door. Think I'll try them first.

Yeah, the easiest and most sensible solution would be to try a progressive approach. I’ll probably try a new seal first.


That’s an interesting approach Paul. Forum member Willis ( Rob ) , has generously offered me a used one he had, so I’m gonna give that a go.
 
True Jim - but the point is that those camshaft seals are about the only thing on these engines that persistently leak (as long as the output sprocket nut is tight) - and so SOMETHING is promoting that leak and all I can think of is the pumping action of the double set of ball bearings.

Maybe the fit of the camshaft on the seals is wrong - or maybe the surface finish is poor......
Pete,
It is my understanding that you have been working for the automotive industry as well. I do know that some oem engine crankshaft seals have some kind of "oil pumping grooves", which are made for that engines specific direction of rotation. I am pretty sure Volvo Penta marine engines have this type of seal at the drive end of the crankshaft, and that fitting a generic seal mostly leads to oil leaks. Has anyone investigated this? OEM Yamaha vs generic seals? Obviously, the camshaft would require one seal for clockwise, and one for counterclockwise rotation. Just a thought anyway.
 
I do know that some oem engine crankshaft seals have some kind of "oil pumping grooves", which are made for that engines specific direction of rotation.

I have a couple rotation specific cam seals on hand right now, but not a matching set of right and left. They both are for the same direction.

A2E669C8-84F0-4AF7-AA19-DE77F0013F9A.jpeg
 
I have a couple rotation specific cam seals on hand right now, but not a matching set of right and left. They both are for the same direction.

View attachment 164301
It would be interesting to see how those worked out. Unfortunately it looks like they are correct for the RH/ ATU side, and would increase any oil leak on the ignition side. Are those OEM Yamaha?
 
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