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British Bikes / Re: AJS 16M 1951
« on: August 12, 2025, 02:50:10 PM »
Buy both! You can’t have too much info.
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2
British Bikes / Re: AJS 16M 1951
« on: August 12, 2025, 05:33:42 AM »
As you know, your AJS is essentially a re-badged Matchless. By far the best owners workshop guide for you is the “MotorCycling” Maintenance Series covering Matchless 350 & 500 cc Heavyweight Singles 1939-1955.
Republished by Bruce Main-Smith Ltd in 1976 and as they say “intended for Matchless but good for AJS too.”
It contains every bit of technical information you’ll ever want to know plus all the technical differences from year to year and lots of clear illustrations. You’ll love it.
A4 landscape size, published by Bruce Main-Smith Ltd and edited by Reg Hide. Get a copy.
Republished by Bruce Main-Smith Ltd in 1976 and as they say “intended for Matchless but good for AJS too.”
It contains every bit of technical information you’ll ever want to know plus all the technical differences from year to year and lots of clear illustrations. You’ll love it.
A4 landscape size, published by Bruce Main-Smith Ltd and edited by Reg Hide. Get a copy.
3
British Bikes / Re: Villiers centre piece carb MKII: internal dimension?
« on: August 12, 2025, 05:09:39 AM »
I have never seen any information on the internals of the Villiers centrepiece published anywhere….ever. Further to that, as the centrepiece is made in two parts and very tightly assembled, they went to great pains to tell people NOT to disassemble them so as to look at the internals. There is nothing to gain from doing so and every chance of creating problems for yourself if you do.
Over a long period the top hole of the centrepiece may be worn out of true by the working action of the taper needle. Slight wear may be compensated for by a change of needle but for the effort and time wasted to do this and get it right it is far easier to just simply fit a new centrepiece and be done with it.
Villiers may have altered the internal arrangements of the centrepiece several times over its lifetime. We don’t know, we have no way of finding out and does it really matter? Regardless of the internal arrangements the MW carb on your Mk XIIC still runs best with a number 2 centrepiece. That is all we need to know for successful operation.
Over a long period the top hole of the centrepiece may be worn out of true by the working action of the taper needle. Slight wear may be compensated for by a change of needle but for the effort and time wasted to do this and get it right it is far easier to just simply fit a new centrepiece and be done with it.
Villiers may have altered the internal arrangements of the centrepiece several times over its lifetime. We don’t know, we have no way of finding out and does it really matter? Regardless of the internal arrangements the MW carb on your Mk XIIC still runs best with a number 2 centrepiece. That is all we need to know for successful operation.
4
British Bikes / Re: Villiers centre piece carb MKII: internal dimension?
« on: August 11, 2025, 02:43:51 AM »
The Mk II designation on the underside of the float bowl refers to general improvements across the whole Villiers carburettor range. It serves no other purpose and has no role in identifying any individual part or individual carburettor. Ignore it.
Your 1 1/8" carburettor is a Villiers MW (Medium Weight). It is intended for use with a Villiers lever throttle NOT a later self closing twistgrip throttle.
The Mk XIIC was fitted with the MW (Medium Weight) carburettor as standard. It was set up with a number 2 jet (the centrepiece) and a number 4 taper needle. Both the jet (centrepiece) and taper needle are stamped with the relevant numbers. Be aware it is very easy for the MW needle and centrepiece to be confused with the similar but shorter parts used in the Villiers LW (Light Weight) carburettor. It is easy to confuse the two.
If all parts are in good condition with the float level set to Villiers specifications the carburettor will work exactly as the maker intended without any further adjustment. Please note there is often a difference between what the maker intended and what a current owner thinks it should do.
Your 1 1/8" carburettor is a Villiers MW (Medium Weight). It is intended for use with a Villiers lever throttle NOT a later self closing twistgrip throttle.
The Mk XIIC was fitted with the MW (Medium Weight) carburettor as standard. It was set up with a number 2 jet (the centrepiece) and a number 4 taper needle. Both the jet (centrepiece) and taper needle are stamped with the relevant numbers. Be aware it is very easy for the MW needle and centrepiece to be confused with the similar but shorter parts used in the Villiers LW (Light Weight) carburettor. It is easy to confuse the two.
If all parts are in good condition with the float level set to Villiers specifications the carburettor will work exactly as the maker intended without any further adjustment. Please note there is often a difference between what the maker intended and what a current owner thinks it should do.
5
British Bikes / Re: Villiers engine in 1930s Waratah
« on: July 04, 2025, 02:14:17 PM »
Given that we know catalogue illustrations of any make can have errors and makers were not unknown to send the odd NQR (Not Quite Right) model out here. I can never get too excited about minor differences.
Personally I go along with Cardans “commercial pragmatism”, with Excelsior juggling the demands of the Australian Excelsior agent (whoever they were) plus William Bros Waratah plus using up as much redundant stock cheaply as possible as they could get away with. We’ll never know all the minor differences and does it really matter?
As for the myriad of differences between the various Villiers 250’s I'm not surprised at the odd publication getting them tangled up. I do the same. With the massive amount of wordage generated about them all a serious reader knows better than taking all these reports at literal face value. There’s bound to be a certain percentage of mistakes.
Do we need to know more or do we know enough?
Personally I go along with Cardans “commercial pragmatism”, with Excelsior juggling the demands of the Australian Excelsior agent (whoever they were) plus William Bros Waratah plus using up as much redundant stock cheaply as possible as they could get away with. We’ll never know all the minor differences and does it really matter?
As for the myriad of differences between the various Villiers 250’s I'm not surprised at the odd publication getting them tangled up. I do the same. With the massive amount of wordage generated about them all a serious reader knows better than taking all these reports at literal face value. There’s bound to be a certain percentage of mistakes.
Do we need to know more or do we know enough?
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British Bikes / Re: Villiers engine in 1930s Waratah
« on: July 04, 2025, 12:40:40 AM »
Yes we do. We went down that rabbit hole exhaustively some time back. You’ll have todo a little exploration of earlier posts.
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British Bikes / Re: Villiers engine in 1930s Waratah
« on: July 03, 2025, 02:13:03 PM »
I’d expect that to be a Mk16A, 67x70mm bore & stroke, made 1934-40.mainly viewed as the standard 250cc workhorse of the range.
Villiers made a surprising range of 250’s in that period. With Autolube system or petroil, air cooled, water cooled, short stroke or long stroke, flattop piston, deflector top piston, long bush plain main bearings or ball race with seals. Yer pays yer money and takes yer pick.
The 16A was about as standard as it got. Petroil, deflector piston, long bush plain mains. Well tested technology but will plonk along forever.
That particular Waratah looks very much like the 1938 Excelsior Meritor.
Villiers made a surprising range of 250’s in that period. With Autolube system or petroil, air cooled, water cooled, short stroke or long stroke, flattop piston, deflector top piston, long bush plain main bearings or ball race with seals. Yer pays yer money and takes yer pick.
The 16A was about as standard as it got. Petroil, deflector piston, long bush plain mains. Well tested technology but will plonk along forever.
That particular Waratah looks very much like the 1938 Excelsior Meritor.
8
British Bikes / Re: Hot Start Problem
« on: July 03, 2025, 09:34:22 AM »
I’ve been plodding through my early BSA literature. It’s made interesting reading. I hadn’t known BSA gave their ignition timings using full retard for several years. They came in line with standard practice sometime in the mid-30’s. They did a full turn around ferociously emphasising all magneto ignition timings were on full advance. In 1936, the last year of Mr Billingtons particular BSA ignition timing was now listed as 7/16” at full advance.
It was a similar curious story with the tappet settings. They were steadily increased over the life of that particular engine. Mr Billington is correct in saying the settings were inlet .004” and exhaust .006” in 1932 but had listed them as .004 for both the year before in 1931 and increased the exhaust setting to .008 for 1933-36.
Lots of food for thought there isn’t there.
It was a similar curious story with the tappet settings. They were steadily increased over the life of that particular engine. Mr Billington is correct in saying the settings were inlet .004” and exhaust .006” in 1932 but had listed them as .004 for both the year before in 1931 and increased the exhaust setting to .008 for 1933-36.
Lots of food for thought there isn’t there.
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British Bikes / Re: Hot Start Problem
« on: July 02, 2025, 04:39:37 AM »
Jon, you are discussing this problem with a group of Australians all of whom regard 25degreesC as merely balmy, not hot at all and who play with vintage and veteran machinery much older than yours. As a 1932 model pedantically your bike isn’t even vintage. You may have a hot start problem but warm weather and age of machinery are not the root cause of your woes. It lies elsewhere.
I have a practical guide to BSA from 1931 written by D W Munro of BSA and first published in 1948 by Pearson in front of me. In his chapter on servicing old models Mr Munro goes on at length about “The Importance of Correct Ignition Timing” for nigh on two pages, finishing off the second page with other possible causes being weak mixture, tight valve guides, burnt valves and insufficient exhaust tapped clearance.
It may be time to again look closely at all these matters.
I have a practical guide to BSA from 1931 written by D W Munro of BSA and first published in 1948 by Pearson in front of me. In his chapter on servicing old models Mr Munro goes on at length about “The Importance of Correct Ignition Timing” for nigh on two pages, finishing off the second page with other possible causes being weak mixture, tight valve guides, burnt valves and insufficient exhaust tapped clearance.
It may be time to again look closely at all these matters.
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British Bikes / Re: Hot Start Problem
« on: July 01, 2025, 07:03:00 AM »
I’ve been thinking of other possibilities. My vintage side valve experience mainly comes from operating a 1926 Matchless. This has a splash and hope total loss lubrication system with exposed valves and sloppy provision for valve guide lubrication. This created some entertaining stoppage issues that took some time to diagnose and even longer to effectively resolve. As your BSA is only a little younger I was wondering whether you might have the same.
The one that most closely resembles your problem was a sticky exhaust valve. This was over lubricated as the piston did not have provision for an oil control ring (pointless with a total loss lubrication system) much oil disappeared down the exhaust pipe clagging up the exhaust valve guide on the way. This caused mysterious stoppages and refusal to start for no apparent reason. Any sort of fiddling with the engine, checking fuel, checking spark, etc, allowed the engine to cool down, the valve freed itself and it would happily restart with me thinking it was my successful fiddling that did the trick, not the cooling off.
I’m not saying that is your problem precisely but I am saying your problem may lie in the valve operation. Guides slightly too tight, valve lifter a fraction tight and so on. It doesn’t take much for valves to not quite seat when hot yet be fine when cooler.
The one that most closely resembles your problem was a sticky exhaust valve. This was over lubricated as the piston did not have provision for an oil control ring (pointless with a total loss lubrication system) much oil disappeared down the exhaust pipe clagging up the exhaust valve guide on the way. This caused mysterious stoppages and refusal to start for no apparent reason. Any sort of fiddling with the engine, checking fuel, checking spark, etc, allowed the engine to cool down, the valve freed itself and it would happily restart with me thinking it was my successful fiddling that did the trick, not the cooling off.
I’m not saying that is your problem precisely but I am saying your problem may lie in the valve operation. Guides slightly too tight, valve lifter a fraction tight and so on. It doesn’t take much for valves to not quite seat when hot yet be fine when cooler.
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British Bikes / Re: Hot Start Problem
« on: June 29, 2025, 03:15:33 AM »
Of course the magneto could fail after little use. Age and how it has been stored since last done can have serious consequences regardless of mileage done.
I’m currently amusing myself with three radio controlled helicopters. All N.O.S, all received in their original unopened packaging, all looking perfect but all non running due to battery failure through sitting around for the last ten years or so. Electrical equipment can do that if left sitting. Look good externally but moulder away internally. Very frustrating but that’s how it is.
As R says it could also be vapour lock. Side valve engines do tend to run hotter than their OHV equivalent and I have seen some poorly thought out fuel line arrangements as well as R’s failure to fit a Tufnol heat barrier twixt carb and cylinder.
Nevertheless I tend towards electrical failure as my own experiences with vapour lock have been on stinking hot summer days with the engine smelling like a fifty year old fish and chip shop on a busy Friday night. Not just a mere hot start issue.
Tell us how you get on.
I’m currently amusing myself with three radio controlled helicopters. All N.O.S, all received in their original unopened packaging, all looking perfect but all non running due to battery failure through sitting around for the last ten years or so. Electrical equipment can do that if left sitting. Look good externally but moulder away internally. Very frustrating but that’s how it is.
As R says it could also be vapour lock. Side valve engines do tend to run hotter than their OHV equivalent and I have seen some poorly thought out fuel line arrangements as well as R’s failure to fit a Tufnol heat barrier twixt carb and cylinder.
Nevertheless I tend towards electrical failure as my own experiences with vapour lock have been on stinking hot summer days with the engine smelling like a fifty year old fish and chip shop on a busy Friday night. Not just a mere hot start issue.
Tell us how you get on.
12
British Bikes / Re: ACME aussie bike
« on: June 11, 2025, 10:49:41 AM »
This bike is still on eBay but now down to $4k. Maybe this is one of those reverse auctions where the price keeps dropping until someone starts to bid?
I’ll keep watching (if I remember).
I’ll keep watching (if I remember).
13
British Bikes / Re: Villiers XIIC 148cc doesn’t run anymore
« on: June 08, 2025, 09:57:02 AM »
There isn’t much comfort in checking the mainshafts for truth. New mainshafts aren’t to be had. Villiers mainshafts of the period are integral with the flywheel. They can be be ground circular undersized up to .005-.010” off but the centres have to be unmarred and dead true plus be set up dead true to the big end assembly. Not an easy job. I’ve chewed this job over and over, reluctantly coming to the conclusion it’s probably just as easy to make the whole assembly new from scratch. Either way is a drama.
On the plus side the two crankshaft halves are identical which is both a blessing and a curse as it both makes the job easier but is wide open for enthusiastic owners to unwittingly end for end the crank assembly when putting things back together. The wear patterns are different for each side so end for ending speeds up the wear rate until the original patterns reassert themselves.
Old British two-strokes are of dead simple construction but quite subtle to get running really well. Charging in with lots of enthusiasm rarely ends well.
On the plus side the two crankshaft halves are identical which is both a blessing and a curse as it both makes the job easier but is wide open for enthusiastic owners to unwittingly end for end the crank assembly when putting things back together. The wear patterns are different for each side so end for ending speeds up the wear rate until the original patterns reassert themselves.
Old British two-strokes are of dead simple construction but quite subtle to get running really well. Charging in with lots of enthusiasm rarely ends well.
14
British Bikes / Re: Villiers XIIC 148cc doesn’t run anymore
« on: June 07, 2025, 02:42:45 AM »
If you have pulled the engine apart and removed one bush it is best to replace the bushes on both sides to make a proper job of it. Replacing one bush alone is usually just a short term repair, replacing both has long term benefits.
I don’t know of anyone supplying these bushes but as they are so easy to make I just make my own. They can be made of any common phosphor bronze bearing material, there is no benefit in using anything fancy or special. This is a very ordinary job for any skilled machinist.
I don’t know of anyone supplying these bushes but as they are so easy to make I just make my own. They can be made of any common phosphor bronze bearing material, there is no benefit in using anything fancy or special. This is a very ordinary job for any skilled machinist.
15
British Bikes / Re: Villiers XIIC 148cc doesn’t run anymore
« on: June 02, 2025, 08:46:46 AM »
Villiers advised up to .008” wear was acceptable. Whether bushes or crankshaft are worn is irrelevant. It is combined wear that counts. Essentially though, if it’s an easy starter, leave well alone. I find the major problem with old Villiers engines is that owners can’t resist pulling them apart to then find they’re never quite the same afterwards.
I think the fussiest area revolves around the ignition timing and the points. The points cam is on the end of the crankshaft so is directly affected by mains bush/crankshaft wear plus the points pivot hole in the points box wears so the action of the rocking pivot point gets erratic. It’s fascinating to watch when using an ignition timing light. You have this blurred line wandering 4-5 degrees each side of the timing line.
I don’t worry overly much about overheating. All cast iron fixed head two-strokes running a cast iron piston run hot. They cannot do otherwise. Just be enthusiastic with the oil.
I think the fussiest area revolves around the ignition timing and the points. The points cam is on the end of the crankshaft so is directly affected by mains bush/crankshaft wear plus the points pivot hole in the points box wears so the action of the rocking pivot point gets erratic. It’s fascinating to watch when using an ignition timing light. You have this blurred line wandering 4-5 degrees each side of the timing line.
I don’t worry overly much about overheating. All cast iron fixed head two-strokes running a cast iron piston run hot. They cannot do otherwise. Just be enthusiastic with the oil.