sleeving 850 barrels

Hey, progress is going remarkably well with my rebuild,
Cases are in the middle of welding (i've also sourced a spare set)
Cranks been cleaned and is in for grinding.

Now we are onto the Barrels, with them already being 60 over they will need sleeved.
i had toyed with going out to 920 but am not sure if this is the best idea either way it will need sleeved regardless.

The main questions i have are:
I have a chip out the bottom, with sleeving, will this area be machined away? for the new sleeve.

How successful and reliable is sleeving (its not something i have done before)

Cheers
Adam

Hello Adam,
I have currently +80- pistons from M.A.P (EMGO) fitted. They do their job and have a very high quality (machining- wise). Even their weight from left to right is absolutely equal. Try this first before you opt for sleeving.
I also prepare a second set of cyl.- head/ cylinder barrel. For this set I bought a set of billet- pistons from M.A.P. Well, you won't get those in +80. So, stick to the cheaper, casted EMGO's they are ok.
Good luck to you.
Best Regards
Klaus

Adam_R said:

The main questions i have are:

How successful and reliable is sleeving (its not something i have done before)

Cheers
Adam

Click to expand...

Sleeving an air cooled engine is risky. It seems to be dependant on the machinist/technicians "art" to be successful.

One would think the joint between the sleeve and the barrels would not impede the flow of heat, particularly if it is a thermal shrink fit, but that fit is critical to heat transfer, and the joint can never tranfer heat as good as a continuous one piece structure.

Heat travels thru a solid metal by the excitation (vibration) of atoms in the solid. Such excitation is stopped at a boundary formed by a contact interface between two distinct parts. As a result, there is a significant increase in thermal resistance that might be sufficient to cause over heating. At the very least, the engine will run somewhat hotter inside the cylinder, at the worst, the increase of internal temperature can be damaging.

Technicians performing this work have their trade secrets. IMO, a good job requires the outside of the sleeve, and the corresponding surface of the barrels be copper plated, then machined to an interference thermal shrink fit. Plating is a molecular bond, not a contact bond, and transfers the molecular vibrations as if the material were continuous. Of course, there still remains that contact interface.

If you decide to sleeve, check out the jobber carefully .... ask for references, try to contact the owners of the bikes he has done. IMO, it is definitely not a job that should be done by a novice machinist, or even a master machinist who is oblivious to heat transfer.

Slick

What if the sleeve is iron and the barrels alloy? Is that a plus or a minus? Remember a lot alloy cylinders out there are sleeved. I can see
why nikasil has its advantages.

If you re-seelve a cast- iron cylinder I don't see it too critical. After all, we have 2 cast- iron materials with equal heat expansion. So they move together under heat.
It is of course a completely different matter if we have an aluminium barrel with cast- iron sleeves. Here we have 2 diffenerent materials wereas aluminium has about double the heat expansion as cast- iron. So we need to have an interference fit between them to enable the 2 different materials to expand individually. If the fit is to strong it may happen that the liner cracks right arround the upper part. The rest of the seelve may move downwards and the pistonrings hang up into the rest of the sleeve, pulling it down into the crank case with desastrous results for the engine. I saw such a desaster in one of Roger Titchmarsh's 500cc Nourish racing engines. So, to me the only thing that reliably works is the NICASIL- plated aluminium sleeve.
Well, the Alfin cast cylinders with the first BMW R50/5 to the R90S also worked well
Nevertheless due to the different heat expansions of the 2 materials you will probably also have had tensions in the barrels. That's why BMW changed over to NICASIL- plated cylinder barrels for the last air- cooled engines.

Adam_R said:

The main questions i have are:
I have a chip out the bottom, with sleeving, will this area be machined away? for the new sleeve.

How successful and reliable is sleeving (its not something i have done before)

Cheers
Adam

Click to expand...

Depending on the size of the sleeve, a significant part of the original casting at the bottom of the cylinder will be removed. That might include the area of the chip. These are pictures of the bottom of an iron cylinder sleeved for a 920 cc conversion. As you can see, not much is left of the original casting at the bottom of the bore. It's pretty clear from these pictures that you don't need the extra support at the bottom of the sleeve, so any missing chips in this area should not be a problem.





Having said all that, I agree with the other folks who suggested either boring for +.080" pistons or looking for a decent used cylinder that will clean up at a smaller bore. It is certainly possible to get good results from sleeving it back to standard bore, as evidenced by the experience of those who have done so, but the cost of doing it properly will probably not be that different from buying a decent used cylinder, unless you have the equipment and skill to do it yourself.

Ken

The places I've checked in the USA cost about $600 for a Commando including the sleeves, boring, honing, and shipping. A new barrel from AN costs about $860 delivered. In the UK I guess the shipping isn't an issue, but the VAT is. Anyway, for all the Norton/Triumph/BSA rebuilds I've done, I've never failed to find a standard or 20 over set for much less so I always do that if I have a bad barrel.

Thanks for all the replies.
I didn't know about the +00.80 pistons and had assumed that +00.60 was the max safe bore.
Klaus, i was recently reading about the billet versions, are they as good as they look?

Icrken, yes it looks very much like the chipped portion will be eliminated. where did you get your sleeves from? 920 is something i've thought about given my circumstances.

Adam_R said:

Thanks for all the replies.
I didn't know about the +00.80 pistons and had assumed that +00.60 was the max safe bore.
Klaus, i was recently reading about the billet versions, are they as good as they look?

Icrken, yes it looks very much like the chipped portion will be eliminated. where did you get your sleeves from? 920 is something i've thought about given my circumstances.

Click to expand...

Adam,

I didn't do the sleeving on these cylinders. They were done years ago by Q%E in Anaheim, but they haven't done them for a long time, and said they no longer have the information on how they did them.

http://qande.com/site/

The liners came from LA Sleeve. I've bought quite a few sleeves from them over the years, and they are very high quality.

https://www.lasleeve.com/

Ken

lcrken said:

Adam,

I didn't do the sleeving on these cylinders. They were done years ago by Q%E in Anaheim, but they haven't done them for a long time, and said they no longer have the information on how they did them.

http://qande.com/site/

The liners came from LA Sleeve. I've bought quite a few sleeves from them over the years, and they are very high quality.

https://www.lasleeve.com/

Ken

Click to expand...

I should have looked first, didn't see that you were in the USA.