VHA liner installed

[Ian.Taylor]

I finally got around to installing the VHA liner into my spare VHA cylinder.
Heated cylinder, cooled the liner in a snow bank.
When the cylinder was hot the liner was wiped down and it dropped in nicely with a clang as the spigot touched the cylinder.
I used 3 T120 cylinders stacked to weigh the liner down.
Once cooled there is a gap of .004 between the cylinder and spigot.
This gap is removed when the cylinder gets warm.
I thought the spigot was flush on my VHA and flush on the spare.

Maybe it just looked flush.
So my questions is Do I need to push the liner down yet or is there supposed to be a gap?

I cant check my VHA as it's together.

Thanks Guys

[nevhunter]

It will go down when you tighten the Cylinder head, especially when the motor gets a bit hot. You are lucky it has a spigot to stop the sleeve moving down. Nev

[nevhunter]

Liners in AL have a problem of uneven expansion, distortion and heat travel. You would be better with a Nikasil coating or go back to an iron barrell as Velocette did. Nev

[Ian.Taylor]

Thanks Nev

I looked into the Nikasill coating , it seems they can coat up to a max of .040 .
A small firm in Quebec has a great reputation for doing this. Something to think about for next winter.
My original cylinder has been great so far but I would like to back back to STD .

The spare was at .060 plus
Would anyone know how hot a VHA cylinder gets say after a good 30-50 plus mile ride.

I'm curious at what temp does the liner start to move.350 , 400 degrees ?

I did a test on my spare today..at 350-360 degrees the cylinder drops down , not good if the VHA cylinder gets that hot under normal use.

[nevhunter]

The issue is uneven expansion affecting heat transfer and the liner moving in the alloy as well along it's axial dimensions The hottest part will be near the exhaust port area . Maybe 180 C. It's safe to use as it has the spigot at the top and can't go anywhere.Just add a bit to the Piston clearance and go riding. It;s normal practice with any sleeve to add a bit more piston clearance. Nev

[nevhunter]

I'm not sure how available those alloy barrels are and if they fail often by separating from the base which can be somewhat dangerous. IF weight isn't a consideration maybe use the iron barrell with the five head studs. The sleeve plays no part structurally. it's all dependent on what amount of the alloy is left in the walls. Nev

[Roger Gwynn]

There should be a gap between the head and cylinder so that the recess in the head clamps onto the top of the flange of the liner. It cannot then move. Ally cylinders always use a flanged liner, sometimes just proud of the top of the cylinder, by .002/.004" and clamped in place by the head as in SQ4 or as in Ariel singles with the flange sitting in a recess in the head.

[will_curry]

The first five-stud alloy barrels had a reputation for weakness at the flange.
I was told that 7:1 was a high as you wanted to go and anyway with the spark
plug coming in at such an angle the combustion shape needed a vast amount
of advance so there was no point.

Not one of mine. It was advertised on ebay from memory.

[Ian.Taylor]

Thanks Gents
Nev
Not many VHA heads or cylinders left here in Canada.I was lucky to get a reasonably good head and cylinder here as back up in case there is an issue.
With the spare cylinder I'm going to use the clubs new 7:1 piston.
I ended up using a die grinder to cut the liner in half on 2 sides then collapsed the liner.
.No aluminum was lost.

Rodger
funny of all the times I've had my original cylinder off I've never noticed the gap , never noticed on the spare as well.
With the liner inserted it looks flush until one closely looks at it.
This gap is quickly taken up when heated.
Would this gap allow for expansion ?

Will
Geeez I hope that doesn't happen to me !!

[nevhunter]

No it can't do that. The head tightening will hold it down at the top. Are there any of John Budgen's barrels around? . Not sure I'd like to run one of those early ones. Maybe be time to get some stronger style Patterns made and produce new Nikasil ones which would be stronger without the sleeve.. it's a fairly simple casting and would fit a lot of crankcases It would enable a tighter piston fit to be used as well.. Nev