The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: malcolm on 28.03. 2012 13:00

Title: Barrel liners
Post by: malcolm on 28.03. 2012 13:00
Hi sorry for shouting im based at stoke on trent staffs cheers for your reply .do you know if barrel liners are available for the A10  just thinking worse case job on +.065 and worn.will be going stafford show end April with a shopping list im into sidecars at moment probably looking at electric starter conversion much later.unable to put photo on as it says too large,malc

adm edit: split from 'Basic spanner sizes'
Hello Malcolm, some practical hints, keep on topic in the tech boards, instead of asking for "barrel sleeving" in a thread named "Basic spanner sizes": start a new topic.

btw, a search for sleeve , liners or cylinder sleeve will point you to lots of good info already present on the forum. See How to search (,1352.0.html) for some help on searching. Thanks
Title: Re: Barrel liners
Post by: duTch on 28.03. 2012 13:35
 I'm fairly sure you can bore to +80 ('citation needed') you may as well go to the max first?? and I have barrels that are sleeved ,current bore +60- liner about another mm, but have been for a long time, but fairly sure you should be able to get'm, I believe there are different types (cast iron/spun steel?)  some are better but someone else most likely knows more,maybe play google??

Title: Re: Barrel liners
Post by: Rocket Racer on 29.03. 2012 01:47
if the bore is true, +100 is viable.
Although once they have been resleeved the oversizes the sleeves can cope with are more limited
Title: Re: Barrel liners
Post by: renos-a10 on 29.03. 2012 06:53
hi all ,

  If you do this what about the temperature? I think you have a problem to high temperature.
Title: Re: Barrel liners
Post by: Tumbleweed on 29.03. 2012 07:43
hello all . there is a set of liners on ebay right now item 370553475613.   :!
Title: Re: Barrel liners
Post by: KiwiGF on 29.03. 2012 08:15
My barrel is sleeved back to STD and the sleeves are about 070 thick wall.

I'd look up the available sleeve sizes before deciding to go to plus 080 or more in case it makes sleeving afterwards expensive, also you don't want the barrel to get too thin at the bottom spigot end before fitting a sleeve as it can put stress on the spigots. I have heard that the interference fit between sleeve and barrel can made less at the spigot end to reduce the chances of the spigots splitting.

Most of the usual suppliers for bsa's sell sleeves for the A10 I think.

At 070 thick the sleeves I've got would not probably not be thick enough if bored to plus 020 I think it's usual to not bore sleeves once they are worn
Title: Re: Barrel liners
Post by: a10gf on 29.03. 2012 10:00
The ebayseller mentioned:
Seems the can provide everything and anything in the Liners dept.
Title: Re: Barrel liners
Post by: Butch (cb) on 29.03. 2012 15:22
Hmmmm. Going +.020 on your .070 wall thickness sleeves only takes .010 off the wall of course. All things considered I'd still try that.

Mine are sleeved back to std (from a worn +.060) but I've no clue what thickness they are. I'd naively thought they would replace the spigot entirely.
Title: Re: Barrel liners
Post by: KiwiGF on 30.03. 2012 00:10
The liners Westwood list look like they are the equivalent to boring to around +120. So if a bore was at a worn +100 it could most probably still be bored to suit the sleeve.

Whether or not one can go +100 (if one could get the pistons) would I think be determined by whether the spigot was still strong enough (I guess it probably is?).

The Westood sleeves are 2.756 id which is nominally the std bore, but the size probably allows for boring/honing after fitting the sleeve, to suit the pistons. It will reduce from it's supplied size, due to the barrel/sleeve interference fit.

I had my sleeves honed to remove some post seizure scratch marks and prior to fitting some new JP pistons. I asked the reconditioner about boring them to fit oversize pistons if honing did not remove the scratches, he said it would be "marginal" and recommended new sleeves as a safer option and it would not cost me TOO much more.

He would have bored the sleeves to plus 020 if I had asked him to, which would leave the wall about 060 thick, maybe a bit less.

Another concern he had was as another company had fitted the sleeves originally he could not be sure if they had the correct interference fit and if not, then boring them might cause them to slip in service.

I've seen advice that sleeves can be as little as 050 thick but I've not heard experiences about anyone trying that on an A10. if it's ok to do that then I guess the Westwood sleeves could be bored to +020.

This topic on sleeves might become more relevant as we all wear our barrels out to the limit! (whatever the limit is...)

This is the westwood page for A10.
Title: Re: Barrel liners
Post by: Brian on 30.03. 2012 04:38
I've got a pair of hepolite sleeves so I pulled one out and measured it.

The OD is 73.1mm, which is .124" over the std 70mm bore. No doubt different brand sleeves come in different OD's and you can get them made to any size anyway.

So with these you could bore the original cylinder to +.100" and still have enough left to bore and fit sleeves.

Wall thickness is about .070" as KiwiGF has said so going on that you could bore a set of sleeved cylinders out to +.060" and still have .040" wall thickness left.

To sum up, you could bore a set of cylinders to +.100" and still be able to fit liners and you could safely bore a set of sleeved cylinders to +.060".
Title: Re: Barrel liners
Post by: duTch on 30.03. 2012 10:34
So in essence you're saying, that he and anyone else has another couple of rebores before sleeves, hey?
Title: Re: Barrel liners
Post by: KiwiGF on 30.03. 2012 11:54
Nev will no doubt pitch in but on the face if it it safe to bore up to plus 080, and probably plus 100 if pistons are available and if the wear is not allowed to get excessive and if the spigots survive, then go to sleeves of 060 or more wall thickness which can probably be bored to plus 020 and probably plus 040.

A few ifs and probablies....

Personally I would not bore the sleeves given the amount I've spent on billet rods etc but as always everyone will make their own mind up.

It would be good to hear experience of how sleeves last, hopefully I'll be able to start wearing mine out soon!

The engine conditioner I used to hone them was impressed they did not move when the seize happened, I guess that's just another risk as one prolongs the life of aged parts.
Title: Re: Barrel liners
Post by: A10Boy on 30.03. 2012 14:56
I've often wondered what structural strength liners add to a set of Barrels.

In other words, given that +060 or +080 is about the max you can re-bore a set of A10 Barrels to, as any more will weaken the spigot / flange area to the extent that a risk of breakage will be present. If you then have a set of liners fitted, what additional structural strength is added back to the barrels? Is it still at risk? 

Title: Re: Barrel liners
Post by: Rocket Racer on 01.04. 2012 10:38
I was given a set of barrels as fin donors. They had been run by the look of it fairly hard and for an extended period with +100 10.5:1. They were thin flange barrels and both flanges had cried enough with the compression and let go.
One of the issues with norton twin barrels was that many were not bored that true and this effected the ability to overbore consistently.
I have yet to see an equivalent issue with beesas but would suggest if the bores are central so the bottom flange has no weak point then would have no concern going to +100.
Even now those broken barrels are extremely useful.

A side benefit of +80 or +100 is the engine capacity is raised to 682cc or 693cc, not quite a 750 but not far off!
Title: Re: Barrel liners
Post by: bsa-bill on 01.04. 2012 11:11
One of the issues with norton twin barrels was that many were not bored that true and this effected the ability to overbore consistently.
I have yet to see an equivalent issue with beesas

Skilled people at BSA of course, they knew just the correct piece of wood to jam under the drilling machine to get it true *evil*

My Flash was at +60 and I had it sleeved, it's been just great since.
One little thought here folks, please measure your pistons rather than trust whatever +?? is marked on them, there are thousands of pitons out there that will fit your BSA, not all of them where made for BSA's and it's not impossible your +40's are actually not quite or a bit more than a made for BSA +40