56G80S - sleeve or replace barrel

Helpful information and requests for assitance and advice
56G80S
Member
Posts: 3354
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

56G80S - sleeve or replace barrel

Post by 56G80S »

Hi chaps

Head and barrel off. one of the "eyes" on a gudgeon pin circlip had snapped off. bounce about up and down the inside of the pin until finally escaping. Two deep "dots" on the barrel at top of stroke opposite each other with slightly smaller ones at the borrom of the stroke and scoring in between before is escaped, presumably into the crankcase (or possible the exhaust). Rings in piston gummed up tight and immovable except the oil control (or scraper) ring.

Barrel already at +40 (I'd taken it from std to +20 and then on to +40). What to do?

Having just read someone's re-sleeving experience on this forum I'm wary but clearly it must be viable or people wouldn't do it. Positive is that at least one would be starting from scratch with a known quantitiy. Versus replacing the barrel with S/hand one; if I could get one at +20 the piston I have is usable unfortunately the std piston lost. Asking prices for barrels (on fleabay) seem almost to match re-sleeving. Haven't rung T&L yet! Will be calling Steve Surbey at AMC CLassics shortly.

Closed for summer holiday to 3 July!

Johnny B
User avatar
Harry44
Member
Posts: 279
Joined: Sat Dec 17, 2016 5:26 pm
Location: SOMERSET UK

Re: 56G80S - sleeve or replace barrel

Post by Harry44 »

My Barrel is at +60 with a club spares piston and no problems in 400 miles. where's the fingers crossed emoji ?
si is does non opportunus vos postulo a maior pango
User avatar
REW
Member
Posts: 1366
Joined: Wed Oct 12, 2005 10:45 pm
Location: CO DURHAM UK

Re: 56G80S - sleeve or replace barrel

Post by REW »

My 350 at +60 with a club piston for quite a few years and miles now too. Just bore with enough clearance, but that is another story...
Ron

1951 Matchless G3L thumping round the Durham Dales.
56G80S
Member
Posts: 3354
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: 56G80S - sleeve or replace barrel

Post by 56G80S »

I don't believe that going to +60 will be enough to removed the two "pits" either side at the top of the barrel; it would remove the up and down scoring.

Perhaps I'm wrong. I'll have to get the vernier out and see what 20 thou looks like; feeler gauge wouldn't do it.

Johnny B
User avatar
1608
Member
Posts: 2493
Joined: Mon Oct 05, 2009 1:00 am
Location: ESSEX UK

Re: 56G80S - sleeve or replace barrel

Post by 1608 »

Why not let T&L try and bore out to +60. If it does not clean the gouges then re-sleeve. A re-bore will last a long time! if looked after.
User avatar
spookefoote1956
Member
Posts: 1836
Joined: Mon May 01, 2017 7:32 pm
Location: Wales Innit

Re: 56G80S - sleeve or replace barrel

Post by spookefoote1956 »

I had mine re-sleeved back to standard by Weir St Light Engineering Blackburn. Super job and super price.
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
56G80S
Member
Posts: 3354
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: 56G80S - sleeve or replace barrel

Post by 56G80S »

Thanks for the feedback.

Johnny B
pkr87
Posts: 592
Joined: Thu May 06, 2004 1:00 am
Location: KENT UK

Re: 56G80S - sleeve or replace barrel

Post by pkr87 »

My 350 AJS trials bike with an alloy barrel played a similar trick with broken circlip which allowed the gudgeon pin to dig a big groove in the cylinder.That was about 25 years ago and nobody could do anything about it.I put a road bike engine in the bike and left the old engine lying in the shed, 6 years ago I was having some machining done on a MG race engine and mentioned the problem to the machinist who suggested that I leave the barrel with him and he would look at it and 'give it some thought'. About a year later he rang me to say " I've done it"' He had had a special sleeve made by a firm in Australia, bored my barrel to within an inch 'of it's life', fitted the sleeve and bored that to standard. I used a Club piston and found all the other engine 'bits' carefully scattered around the shed, rebuilt and refitted the bike's original engine back where it belongs.It did cost me quite a few 'beer tokens' but was well worth the effort. I have tried boring single cylinder engines right out to their limit but have found that can upset the balancing of the engine so I think sleeving back to standard and ensuring that the piston weight is as near as possible to the original would make for a 'nicer' engine.
SPRIDDLER
Member
Posts: 8542
Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: 56G80S - sleeve or replace barrel

Post by SPRIDDLER »

Happened to my 350 which was already +40 so I scrapped it.
It transpired that the round section 'wire' circlips fitted by the PO were incompatible with the shape of the circlip locating recesses in the piston which were shaped for stamped-out square edged circlips.
Image
'There is a tide in the affairs of men
Which taken at the flood............'
56G80S
Member
Posts: 3354
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: 56G80S - sleeve or replace barrel

Post by 56G80S »

Even more thanks!

Although the Matchless has revvd quite freely and I have run it at 70mph (+?) particularly on the way back to N Yorks from the Woolwich Cententary (only had battery, no dynamo and pre LEDs) I'm stuck for the balancing without splitting the crancases as when the duff replacement cranpin failed (and I had a sidecar with a box on) Alpha fitted "an oversize pin". I was only 20 -21 and just accepted this with no details.

The same pin still running and there's no up and down play in it. The con rod does move some, across the frame movement, but nothing that suggests need to replace what's there.

It must be jolly good through, taken a lot of hammer.

I'm going to contact Weir St Light Engineering Blackburn re the barrel and see what they say.

Johnny B
Locked