Britbike forum Forums British motorcycles in general British motorcycles in general K-Liners ??

Stolen from Allan G post.... "K-liners if done properly work really well"
What are these? Are they common? Sometimes I find I've been in the dark!

This comment is from an Australian Harley bike racer I know and respect..

"Some years back we tried guide liners in HD heads and had an issue with the liners moving, the deduction made was that they hung in there quite well until the engine experienced a running high temp situation, which with an air cooled motor was not a rare circumstance.[these were installed by a engine reconditioner that were an industry standard in their day].
I have not revisited the process since, maybe they lock in better these days or another poster may have a better way of guaranteeing their location in the guide. If this is possible the alignment issue would be negligible.I dont know how a bronze liner would go in a bronze guide."

Guide liners, so instead of risking damage to the head by removing and then reinstalling new guides the old ones are bored and relined back to size with the guide still in the head. Like resleeving a barrel. Google 'K liner' for more info.

I have used them regularly in three commandos I have restored. A bsa spitfire. And trident heads. Someone recently mentioned that if you use them on the bronze guides on tridents it makes the too thin and may fracture. But the amount you take out to fit.You replace with the liner!! Anyway food for thought. I can't comment because all the bikes I have fitted them to still running good.They have been used in the auto and diesel industry for a long time.I have a local hot rod guy who does my work. He swears by them.

Ok, so some good machining required. I guess I’d still go with guide replacing if parts are available. Heated head, and reaming to size can be done by an owner. My mentor did disparage bronze replacement guides though I was not sure why the strong comment.

Of course, what you can do is similar to the A65 crank bush, buy oversize guides and after removing the old guides, measure the bores and cut the diameter of the oversize guides to fit.

I learned about them from a friend who has a rocket 3, that bike has been all over the world on BSA events, mostly 2-up and he seldom hung about.

I had my original oif head with bronze guides done at the same place back in 2008, never had a problem with the liners, though the valves I bought were crap and when I changed them, I found the new plasma hardened SRM valves had a bigger stem size to the rubbish I fitted previously. So I reamed the K liners to the new size. They worked fine since.

I’m using a small port head at present which had iron guides. Again these needed reaming and the seats lapping with the new valves but they have been fine on the original guides.

The oif I have just built, Also has k liners.

Like lot of new idead, when they first came out every head shop jumped on the bandwaggow without reading the song sheets first
Thus a lot were done really badly
So for the first decade the accepted wisedom was OK for inlet , disaster for exhausts
Now the workshops have done 3000 warranty repairs they seem to have the process down pat

The only four strokes I have are really, really ancient. 1926 and 1928 Matchless. The factory provided no means whatsoever of lubricating the valve guides and over many, many years of ownership I've learnt the hard way about keeping the idiot things lubricated. Being a total loss lubrication system the exhaust guide presents no problem. Enough oil gets past the piston (no oil control ring) to keep it happy but the inlet is something else.
As standard the inlet valve will start to nip up at the first sign of an uphill slope. Spitting back through the carb is a sure sign it's about to nip. A quick change down and a slow potter at walking pace then keeps everything happy but it certainly stops any thought of giving the bike a handful and cracking along.
This was frustrating for years but K liners and high temp silicone grease have made a magical transformation. Silicone grease alone was a great find but with the K line dimples holding just that little extra bit of grease the effect lasts a lot longer. Spit backs and nipped up inlets are a thing of the past.
You could say I'm a happy K liner convert.
Cheers,

That is going straight to the pool room as well.

How do you apply the silicon grease? Being Vintage (even late Vintage), it wouldn't surprise me iif part of the weekly maintenance is to whip the head off. pull the valve out and grease the valve stems by hand.

You and me both.

It's quite simple.
These are fixed head sidevalve engines with aluminium 'fir cone' valve caps plus the lower end of the valve stem with spring, etc, is open to the air. No tappet chest, no telescopic covers, no nothing. The gap between the top of the engine and bottom of the fuel tank is such that the valve cap can be removed and valve lifted out without removing the tank.
I have long since assembled the exact tools needed to do the job with minimal effort. Easy removal of the valve caps without damage in the space available requires its own special ring spanner which I cut out of flat plate years ago. Standard ring spanners tend to tear the corners off these valve caps whereas my single hexagon ring spanner spreads the pressure and doesn't harm them. Early owners would have used a box or tube spanner but that requires the tank to be removed so I don't go down that track.
Aluminium valve caps don't require the sealing washers as used on cast iron and bronze caps as theoretically the aluminium expands more than the cast iron cylinder when hot. I ensure sealing with a smear of Dixons PJC, an equally ancient graphite heat proof paste that also ensures easy removal next time.
There are no collets at the bottom end of the valve stem. I still employ the original slot in the stem method with a little piece of 1/8"x3/8" flat. It can't fall out when the spring is compressed but is easily lifted out with snub nose pliers. Fancy collets would be a clumsy pain and unnecessary in this application.
I have a funny little spring compressor vaguely along the lines of the old flathead Ford variety. Using it compresses the spring in place but I can remove the valve without hindrance. All very easy when you get familiar with it.

Basically, I can grease the inlet stem and clean guck off the exhaust stem (another story)in about the same time it took me to write this (probably less).

Ahh, I was thinking of those fancy newfangled overhead valve thingies. I didn't think there was much lubrication in the valve chest of later side valves in any case, but there must be enough.

I wondered about the slotted valve stem used with Vintage side valves, but it's clearer now. I have a 1920s BSA 3.49 h. p. motor with that setup.

I've had several vintage ohv Matchless. They also did ohv versions of the sidevalve stuff I have. Their ohv set up was a nightmare to renovate so in the end I cheerfully chose sidevalve as it was so much more practical.

AS with the sidevalves Matchless didn't provide means of lubricating the ohv valve stems either although gravity made life much easier getting lube in to ohv guides. Nevertheless broken rockerbox castings from valve seizures (something has to give) were a constant worry. The worst problem was the actual rockers themselves. Unlike later Matchless rockers they were solid forged and ran in a roller bearing arrangement. The rollers ran direct on the rocker surface and wore grooves in it. They "Brinelled" into it. Rollers on a reciprocating surface where the roller movement is concentrated in a small area is not a good idea, and having an unrepairable one piece solid forged rocker just made things worse. I did exchange the rollers for a plain bronze bush in a couple of engines doing nothing about the worn grooves except slathering grease in there but was never happy with any of it so it was back to sidevalves for me. The wear pattern was curious. Rockers reciprocate very little so the rollers barely move. They then ferociously wear these grooves in the rocker. Most of the rocker would be unworn but there was no way of moving the rollers to the unworn areas.

Anyway after many years of this nonsense I unintentionally ended up with a vintage Villiers powered Excelsior. It proved a real surprise and I've enjoyed two-stroke bliss ever since. I'd dearly like to run the Canonball with a vintage two-stroke just for the fun of it but The Manager would had a spasm at the thought.



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My limited experience with bronze valve guides is this, stem to guide clearance is CRITICAL especially on the exhaust side.

More of a issue with solid bronze guides but evidently the expansion rate for bronze in quite high and if set to spec for iron guides the exhaust valves will stick in the guides when they get hot, extra clearance is required.

Just went through this on a supercharged engine build for my 63 Austin Healey Sprite, engine ran fine until a long uphill run and suddenly out of nowhere mifire and valve train noise that would go away if the engine allowed to come back to idle. Was hoping that the clearance would open up with time but no such luck, ended up having to remove head and ream/hone guides to get nearly .002 on the exhuast side.

Luckily with the relatively mild cam and dished pistons there was no chance the valve could hit the piston but still an annoying leasson to learn.

Can you give us the details on that grease?

Hmm, I have a nicely equipped 'Cannonball trailer', so an interesting overseas rider with an interesting bike could provide a compelling reason to try my hand at using it and being support crew.

The Indian Pacific run next year from the WA coast to NSW coast might get past the keeper. I haven't heard from the organisers in a while, but I think it's still on.

Yes Doug, I went through the bronze valve guide nonsense as well as trying various grades of cast iron down to and including making guides out of old sash window weights. They were recommended to me by a fellow vintagent as being items made from the rubbish of any foundry pour and full of impurities including much graphite thus being self lubricating to a degree. Didn't work for me although he was right about the blowholes and muck I found when turning them up.

I also learnt that bronze valve guides really, really do need a certain amount of positive lubrication and they weren't going to get that in a vintage Matchless engine.

As for the silicone grease MM, that was a freebie from a mate who ordered a particular dielectric silicone grease (whatever that is) and got this high temperature stuff instead. The wholesaler it came from carefully stuck their label on top of the manufacturers details so I can only tell you it was produced by a firm called 'Chemlube'. Their blurb for it reads as follows, "Chemlube silicone grease is a multi-purpose industrial grease with excellent dielectric properties, moisture and oxidization resistance.It will withstand temperatures within the range -40 degree C to around 400 degree C and is resistant to a wide range of chemicals. Will not effect natural or synthetic rubber in seals, valves or bearings."

I don't think there is anything exceptional about it, it's just another industrial grease for specific purposes.

Finally if a two-stroke could be interesting on the Canonball, that same mate would stop it in it's tracks as he runs a couple of Barr & Stroud sleeve valve engined bikes. Like ancient two-strokes, sleeve valve engines have an undeservedly bad press and the reality comes as quite a surprise to the standard motorcyclist.