1931 Model 10 350cc OHV Sunbeam motorcycle


For the last 45 or so years, I have always had at least one classic bike in the shed. For much of that time they were just old bikes; worth very little and used as day to day transport. Most of them were Nortons, but like most others of my era, I picked up whatever was around at the right price or could be swapped for whatever I had tired of. Since early retirement a few years ago I have had the opportunity to work my way through some of those that I've never previously owned - including a Velo Venom, BSA A10, Matchless G80S and Triumph unit twin.

Pre-war hand-change machines have always fascinated me, and think the Sunbeams of the vintage and immediately post-vintage eras are particularly attractive. So when I saw a 1931 Model 10 350 on offer from Andy Tiernan in Suffolk, I couldn't resist making a deal with my Triumph and a substantial cash contribution.

The Model 10 may not have been the best choice for a first-time early post-vintage machine: produced for only 2 years, being Sunbeam's response to the Depression which had seen them largely priced out of the market, as most of their machines were seen as (and were) more expensive than much of the competition. Sadly for the company, it did not sell well even at £65 and I believe only a dozen or so are still in existence. Much of the bike is specific to the model, and I shudder to think of the tooling and production costs of bringing a totally new design to the market at such a time. This of course makes sourcing spares a real problem.

However, I like a challenge, and thought the Model 10 was a very handsome machine, having a lean purposeful stance and being devoid of the spaghetti-like oil plumbing seen on other contemporary Marston models. A Motor Cycle road test of the time suggested that few machines could be more charming on the road and that it was fast, smooth, comfortable and handled superbly with exceptional acceleration. It was also said to be able to achieve 100 mpg - I suspect largely due to its very low weight (230 lb or around 105 Kg) and minuscule 7/8" bore carburettor, and had the "impressive yet restrained appearance for which the make has always been famous".

A visit to the VMCC library at Allen House provided me with a number of photocopies of period magazine road tests etc that have proved very useful, as did the magisterial Sunbeam history from Bob Cordon-Champ. In common with many pre-war manufacturers, Sunbeam's own publications are sketchy in the extreme and the manual (obtained from the Marston Sunbeam Register) makes only passing reference to the Model 10. The Pitmans book is little better and the parts list is similarly unhelpful with blotchy and blurred drawings which give little indication of what parts look like or how they are assembled. There was a little information on the Marston Sunbeam Club (which I joined) website and www.Sunbeamsidevalve.com. So unlike most of the bikes I've owned, I was very much on my own with this one.

As bought.

as bought 1

as bought 2

The blurb from Andy Tiernan's website suggested that the Model 10 was ready for final fettling although I have to say that was optimistic in the extreme. The photographs rather flattered the bike as is often the case, the paintwork especially being in a much poorer state than it appeared. Still, I have no-one to blame but myself as I bought the machine sight unseen. I have rarely bought bikes via dealers, much preferring to deal direct with a previous owner, and suspect I wouldn't repeat this particular error. However, the part-exchange deal did mean that I wasn't left with another bike on my hands which I would have needed to move on - my garage not being able to cope with the vast stables some seem to manage. It's always a case of one in one out.

Once the Model 10 arrived I discovered that it had been through a number of hands and had been returned by at least one buyer as not up to standard. However, that buyer had paid substantially more than I had (although I think I paid quite enough).

When it arrived it was obvious that a number of items required immediate attention:

Having said this, the machine was largely complete.

I had hoped to do some light tidying up before putting it on the road, but this list of faults (especially clutch and brakes) made me decide to put it to one side, enjoy the remaining weeks of summer on my modern(ish) machine, and start serious work in the autumn.

I'm not a great fan of the so-called original and unrestored machines which are currently fashionable as in many cases these are nothing more than rusty neglected heaps - or indeed complete fakes such as the 1930s Norton featured in a recent edition of RealClassic magazine. I do make an exception for real historic machines which show the authentic marks of a life well-lived such as Ted Simon's Triumph currently residing in the Coventry Museum of Transport. It's most unlikely that a bike has lasted well over 80 years without having major components replaced. On the other hand, I wasn't aiming for a dazzling concours winner as that would probably make it unlikely to be ridden (or indeed ever finished) as well as driving costs to an unacceptable level. Smart, tidy and well-cared for was the state I was after. I also wanted to keep as much of the original bike as possible (although of course how much of it left Sunbeamland at the same time is a moot point).

Clutch and transmission

The first task was to check out the clutch. As I dismantled it, it became clear that it was a mismatch of bits and bobs, some probably not even Sunbeam. In particular the backplate had been crudely welded to the kickstart ratchet and had an extra clutch plate welded to its face. The whole lot was eccentric and wobbled all over the place. However, the pressure plate and corks seemed to be in a reasonable state. It is a variation on the single spring design, which does not enjoy a positive reputation, fitted to some other Sunbeams.

I was fortunate to meet Vic Youel of the Marston Sunbeam Club at the VMCC Founder's Day event and he very kindly supplied me with some (almost) correct parts to rebuild the clutch. Once I had these and had made the necessary modifications including turning a split spacer to align the primary chain, it was possible to turn the engine over and I was pleased to discover that compression was reasonable and that the engine turned freely. Later careful attention to the operating mechanism gave me a clutch that freed reasonably well although with some dragging. Adjustment is critical - a slight turn on the adjuster makes a huge difference.

The Sunbeam range with the famous oilbath primary chaincases are fitted with clutch stops. The idea behind these is that when the clutch is fully withdrawn the pressure plate contacts the stops which are fitted in the outer chaincase, slowing it down and helping a clean gearchange. I tried the "book" method of setting these with little success, finally developing a way of adjusting them one at a time. First I unscrewed them both till they were well clear of the clutch plate when on full lift. Then, by putting the bike in top gear on the stand and adjusting one stop inwards until when the clutch lever was fully pulled in it became hard to turn the back wheel I could tell that the stop was contacting the plate. I then backed that stop off a full turn, repeated the process with the other, finally resetting the first stop. This did seem effective when I actually rode the bike for the first time.

The gearbox selected all gears smoothly and turned quietly although virtually devoid of oil, so after adjusting the linkage I decided to leave well alone and merely to replace what oil was in the box with Spheerol semi-fluid grease giving less opportunity for it to leak all over the back tyre. The primary chain and engine shock absorber were in good order although I had to make a crankshaft nut with a shoulder and castellations for the split pin.


As mentioned, neither brake worked on delivery. Both cables were rusty and the outers frayed but I always make new cables for any newly obtained machine so that was not a problem. When I took the wheels out it was clear that the linings were useless so I had new high friction linings fitted by Villiers Services in Merry Hill. They do an excellent job and are happy to fit appropriate linings for the size of drum. Once fitted, the brakes seemed much better although of course I would have to wait for a road test before being completely satisfied.

Paintwork and Plating

Although the cycle parts were basically sound and had the benefit of a good primer coat, the finish was very poor and there were large areas which had been missed altogether. In general however, the underlying metal was sound. So I decided to repaint everything except the petrol tank which was stated to be new and, to be fair, had a reasonable finish although lacking the customary gold lining.

Much work rubbing down and many coats of Hycote Bodyshop black aerosol resulted in an acceptable finish.

The frame and smaller parts were no problem; I always find mudguards a bit difficult as it's necessary to paint to a wet edge which is tricky with a big area but was happy with the results. I used 3M narrow flexible tape to mask out the tank for the gold lines which I applied with another aerosol. Not up to Marston standards I'm afraid but much better than it was when it arrived.

The brightwork on delivery was in a very poor state so I entrusted chroming and some nickel plating to a local firm, Chromefix of Balsall Heath, who did an excellent job at a very fair price. Again wishing to retain as much as possible of the original, I opted to keep the exhausts despite some minor dents as I felt these added to the character of the bike.


I already knew the exhaust valve lifter and oil pressure tell-tale were missing. Unique to the bike, it was most unlikely that I'd be able to find replacements so needed to manufacture them. I have a Granville centre lathe (cheap Myford copy) which is probably of similar vintage to the Model 10, so designed the components to suit the style of the bike and (with many helpful suggestions from the IKBA forum) set to producing piles of swarf and eventually ended up with reasonable items.

This is the valve lifter:

valve lifter

All Marston Sunbeams have oil tell-tale or pressure indicators, but the thread locating this component in the timing cover on the Model 10 is different to the others being 7/16" Cycle. I sketched what I thought I needed and uploaded this to IKBA for comment. Some very helpful feedback improved my original design substantially so I set to with the trusty Granville and produced an item which looked the part and, more importantly, seemed to work effectively.

telltale 1

telltale 2


telltale 3

The rocker box, head and barrel were removed as a matter of course and I was very pleased to see that almost everything seemed in good order and clearly had run little since last being assembled. The piston, bore and rings were fine. There was no appreciable play in the big end or main bearings and the crank rotated smoothly so I opted to leave the crankcase assembled. I did however need to make a new phosphor bronze bush for the exhaust rocker spindle.

When I had the assembled head upside down to check valve seating, I was horrified to see one of the exhaust valve collets drop out onto the bench! If this had happened with the engine running, it would have been a disaster. I found that the collets were entirely the wrong profile for the spring retainer so again, replacements not being available, I turned a pair out of a scrap HT bolt. Getting the taper right was tricky but eventually I was satisfied with them. The collet locating groove in the valve was also somewhat bashed about so I used a Dremel with a small mounted grindstone on the lathe's toolpost to tidy this up - it only needed a light cut to restore it. After checking valve and guide wear (within acceptable limits) I could then reassemble the head.

One of the long head studs looked as if it had been filed from an old bit of scrap so I made a new one (double diameter as the bottom end thread in the crankcase had been enlarged) out of stainless.

Timing cover

This had clearly been through the wars. The extension for the magneto chain had broken at some time (probably due to levers being used to remove the magneto sprocket) and repaired with a steel fishplate.

timing cover

The lower extension which contains the oil feed from the sump to the pump had been overtightened and fractured, possibly by the same owner, and repaired with brittle glue of some sort.

I tried all the avenues I could think of to source a replacement cover but hen's teeth seem to be easier to come by. So I had to live with what I had, replacing the brittle glue with JB Weld and using a thick paper washer and Loctite 5922 to make an oil-tight seal at the joint with the crankcase / sump. I had considered a welded repair, but general opinion was that such an old casting would be very problematic and I didn't want to end up with an unusable component.

Magneto sprocket

When I rotated the engine I was alarmed to see the whole magneto moving up and down with the engine rotation. Removal of the chain cover showed the chain varying between bar taut and totally slack. It was clear there was some eccentricity somewhere. When I removed the mag sprocket I could see that it looked quite bodged and that the sprocket itself was welded to the cylindrical portion rather than being integral with it.

Making a new one was beyond my (and the Granville's) capabilities so after making a sketch of the required item I contacted Bob Humbernut Rodgerson who kindly put his new CNC machine to use and made me a super component which ran very true. There was still some variation in chain tension but selective assembly of the drive sprocket on the inlet cam spindle reduced that to an acceptable level.


As delivered, the electrical system looked complete although lacking bulbs and any trace of wiring. Against better advice, I decided to rebuild the 3-brush dynamo as original complete with its internal cutout and half-charge resistor in the light switch rather than convert to 2-brush operation and a solid-state regulator. The dynamo was in a real state having its field winding and brushes all disconnected. However, it was relatively straightforward to strip and rebuild it (although the system of earthing the field through the light switch and its internal resistor rather than supplying a live feed to it as on later versions caused me some head scratching).

The drive end bearing was very rough so I replaced that although the commutator end was fine. A quick skim of the commutator with a sharp knife tool in the lathe followed by undercutting the mica segments and charging was enabled. I tested it by mounting it under the pillar drill, driving with a bit of rubber hose to account for misalignment and with the field coil terminal earthed got a satisfying voltage rising to around 12 volts. I tested the integral cutout by applying 12 volts from a spare battery to its input which resulted in a satisfying click. I hoped that it would cut in at the required 7 - 8 volts.

The commutator end:

dynamo 1

Test rig (pillar drill driving through a bit of rubber hose). Not running as I didn't have enough hands to hold it steady as well as taking a photo:

dynamo 2

The wiring was a straightforward job; I used black thinwall PVC insulated cable housed in nylon braided sleeving throughout: not original but it looks the part. It goes without saying that there are no pre-insulated crimp connectors to be found. A pattern dip / horn switch and 6 volt bulbs were sourced from Ebay. I always fit dedicated earth wires connecting the battery, engine, handlebars and headlamp to avoid problems resulting from fresh paint, grease etc. I fitted a small gel battery inside the hard rubber Exide case that had arrived with the bike as I've found these batteries to be cheap and reliable. A 15A blade fuse was fitted on the earth side which I believe gives slightly better protection than one fitted on the live terminal. The incorrect fluted headlight lens was replaced with frosted glass from a local glass merchant. Finally a cheap ebay bicycle speedo was fitted to avoid being done for speeding (I should be so lucky.....)

Lucas helpfully provided a wiring diagram on the rear of the light switch:

light switch

Testing the magneto with a cordless drill showed a good strong spark even on full retard so all I did was to check that the spindle rotated smoothly, remove the points and clean them up and refit / regap and put it all back together. Fitting the magneto and adjusting its chain tension was something of a nightmare as access to the securing nuts was very restricted. I understand that Sunbeams were supplied with a special bent spanner as part of the toolkit but unfortunately this was missing from my bike. Timing was a simple operation - I use a piece of kitchen foil to detect the points opening as I find the usually recommended Rizlas too fragile. I did feel the specified timing figure of 5/16" (30 degrees) BTDC seems a little on the late side. However, it should prevent pinking on unleaded 95 octane.

Cycle parts etc

The wheel bearings rotated reasonably smoothly and could be adjusted to give minimal play at the rim so I opted to leave them in place and merely pack with fresh grease as I was very doubtful about sourcing replacements. I was entirely new to girder forks so decided to strip them, being pleased to find little wear in the spindles and links so again reassembled with fresh grease after cleaning out the old stuff.

The Cheng Shin tyres fitted were in decent condition and of an appropriate pattern, and as I plan to ride the Model 10 only in dry conditions I merely removed them, checked the rims and spokes, and replaced the tyres after painting the bare wheels. The rims were pitted but basically sound and the spokes in good condition so in line with my wish to retain as much as possible of the original machine I decided not to rebuild them with new rims and spokes although I always enjoy this task. I didn't want to damage my newly painted rims so managed to fit the tyres without the aid of levers (although copious amounts of tyre soap helped).

Those little bits that always take so long.....

Apart from the items specifically mentioned, there were many small parts either missing or incorrect including head steady, clutch cable return spring anchor, etc etc. All these were easy to fabricate using basic hand tools and material from the scrap box. New control cables were made and fitted all round. One advantage to a pre-war machine is that so much of it is simple in design and capable of being reproduced - or at least decent substitutes made - by the amateur.


I have of course tailored the riding position to my shape and size which means having the handlebars in a high position - leading one IKBA contributor to liken it to a startled elk. I can see what he meant, but comfort and controllability are taking precedence over aesthetics at this stage. Expert Sunbeam owners know that the front brake on most models is to be found on the left hand bar where you might expect a valve lifter, with the valve lifter on the right. This was a step too far so I opted for the more conventional and familiar layout.

Comparison with catalogue pictures:

It runs!

It was with some trepidation that I put a couple of litres of petrol in the tank, opened the petrol tap (noting a slight weep from the union which would require attention), set the ignition to half retard and closed the air lever. A couple of priming strokes then I eased over compression using the valve lifter (which I was very pleased to see worked well) and applied the long swinging kick. This resulted in a cough from the exhausts. A couple more attempts gave the same result so I depressed the tickler for a few seconds and tried again.

It now started immediately and after some minor adjustments to the throttle stop idled very nicely and picked up well to a blipped throttle. However - my oil pressure telltale refused to show any pressure. I stopped the engine and removed the telltale - there was no oil showing in its housing. Following the sketchy instructions in the manual, I tried starting again with the telltale removed but there was no sign of oil appearing at all. So I stopped the engine, retired to the shed and removed the timing cover to investigate.

I must say I had been a little dubious about the design of the lubrication system, which is of the wet sump type unlike all other Sunbeams. The oil level is around 4" below the crankshaft-driven oil pump, and is connected by a drilling in the timing cover. So on initial start the pump is running in air and has somehow to draw the oil up. It's interesting that photographs of the prototype engine in Cordon-Champ's book show a somewhat different lubrication layout so an early redesign seems to have been carried out.

To check the pump operation, I built a test rig which essentially comprised submerging the bottom end of the timing cover in a jug of oil and rotating the pump with a cordless drill. After some time, a bubbly stream of oil emerged from the telltale and restrictor housings. Refitting the restrictor and telltale showed the latter popping out under pressure in a most satisfactory manner. So all that remained was to refit the timing cover hoping to re-achieve the oil-tight fit I had eventually managed on the original build. I had just not waited long enough in my first attempt.

On starting the engine, at first I was concerned that my work had been in vain as the telltale remained obstinately closed. However, as I opened the throttle I was pleased to see it move outward showing that pressure and flow were being achieved. In fact, the design seems to only work above a certain engine speed - possibly there is a threshold below which the gear wheels aren't turning fast enough to overcome the partial vacuum below the pump. So had I been brave enough to run it at a higher speed on my first attempt I could have avoided some extra work and worry.

Deviation, hesitation and repetition

A week or so after this, I was fortunate enough to attend the first National Motorcycle Musem's "Ride a Classic" day. What a superb experience and a rare opportunity to get aboard exotica such as George Brough's personal Brough Superior SS100, a Vincent Black Shadow, and even a Norton F1 rotary whose riding position was unfortunately far too cramped for a normally proportioned human being, as was the BSA RGS also on offer. My favourite of the day was of course the 1928 Sunbeam Model 90 which was superb to ride and handled the tight twisty course easily so I had a couple of shots on it. The bigger bikes - especially the Brough - were at a disadvantage having heavy, slow steering and being far more suited to the open road. Here I am looking rather more confident than I was feeling......

On the road

Having completed the Sunbeam build I was itching to try it (combined with a certain nervousness I must admit). Despite my reluctance to venture out amongst the bank holiday traffic, Good Friday was too bright and sunny to ignore.

So out of the garage, start first kick, on with the helmet & gloves after checking the oil telltale then idling sweetly while I rolled it off the stand.

Into first with a barely perceptible clunk (clutch stops doing their job) then wait at the end of my drive for a break in the cars.

I live on a suburban road in Hall Green and the least stressful route away from home involves 2 roundabouts about 1000 yards apart then a stretch of road about a mile long. All with cars parked on both sides, driveways with inattentive drivers poised to reverse in front of me as well as being used as a rat run at busier times of day.

I managed a successful change to second before the first roundabout then found first while I waited - then through the gears into top before slowing for the next one. I was very satisfied to feel the lack of shake and wobble from the forks although I suppose I barely reached 30 mph.

Crackling away from the second roundabout and up into top I was feeling very pleased so decided to stop and turn round in the road before the point of no return. After which - mini disaster. As I was giving it some throttle in 2nd the back wheel locked up. I whipped the clutch in and I found the engine had locked solid. I pushed to the next roundabout, the light weight being a boon here, letting the engine cool down, and tried the kickstart again to find it had freed off and fortunately still showed excellent compression.

I started it up again and it sounded fine with no nasty rattles so gently rode it home. I suspect the problem is that I hadn't unscrewed the oil feed restrictor enough - it was about 3/4 of a turn out from fully home. There's virtually no information to be found about how to set this. I'll try it much further out. Better to have a blue haze following me than bits of seized piston........

This brief run did show up some areas requiring attention. The throttle had an action like a blunt knife through gravel. The inverted front brake lever was flopping about. Petrol was weeping from the union at the bottom of the tap. The tappets had bedded in and required further adjustment. However most things looked fine. A replacement twistgrip and materials to make a new cable were soon on order; the petrol weep was discovered to be a split union nut (a rifle through my scrap box turned up a replacement); the brake lever shimmed and tappets re-adjusted, all followed by a general check-over for loosened fastenings etc.

A few hours in the workshop with pencil blowtorch and solder had a new throttle cable made. The twistgrip had an internal diameter of 15/16" - matching a reduced section of the handlebar - which I understand to be a pre-unit Triumph pattern so this is what I used although it had to be significantly shortened to allow the front brake lever to be assembled to the end of the handlebar. This all gave a silky smooth throttle operation so was well worth while.

On the road again.....

The first opportunity to try the improvements was a few days later due to other commitments. Fortunately this time it was a bright mid-week day so little traffic to hinder me. Again, a first kick start and I was impressed by the way the clutch took up the drive gradually. I found that upward gear changes were virtually silent, probably thanks to the clutch stops. However, being used to later machines, I was trying to change down at much too high revs and road speed causing some horrific crunching. After some practice, I started waiting for the downward change till the engine was starting to get unhappy on the higher ratio and this proved much better. I know there is a left hand across the tank technique which ignores the clutch and uses the false neutrals between the gears to effectively double declutch - this is a method I will save for later. For the time being, I had realised that I could pull away from walking pace in second with the ignition fully retarded so tried to time my arrival at junctions and roundabouts to use this tactic.

This time I successfully reached my previous furthest point and returned with no problems, and particularly no tightening up as had happened on the first test run. When I returned home I realised that I had now set the adjustable oil feed too far out as I was getting quite a lot of oil around the valve guides so screwed it in to be around 2 turns out from fully home. I also decided that the spring in my oil pressure tell tale was on the strong side as it was tending to stay in, despite a good flow of oil, so substituted a lighter one.

After these minor adjustments I again set off for a rather longer run, of about 5 miles, including the aptly named Paradise Lane (some lovely Victorian cottages) and Webb Lane in honour of the front forks. Everything was going well: the front brake was now offering some retardation although the rear was still poor; my cycle speedometer showed I'd reached a speed of 40 mph with no concerns about the handling; and I was feeling confident that I could take the little Sunbeam further afield.

There were of course a few loosened fastenings and the petrol tap still wept a little. Unfortunately this had dripped on the Little Oilbath transfer which, even though protected by supposedly petrol resistant lacquer had crinkled, so further work yet to be done. The clutch was slipping slightly as it had bedded down so needed minor adjustment. But I was very happy and pleased with my first pre-war restoration and was looking forward to many miles on the leafy Warwickshire lanes.


Having now had the opportunity for a couple of further runs, I am increasingly comfortable with the Sunbeam and the way it goes. Now the slipping clutch is sorted out, it pulls like a train and although I have yet to venture beyond the suburbs, I have seen an easy 45 mph with plenty left to come. The forks cope well even over quite rough surfaces, and the well sprung saddle looks after the other end. The front brake is bedding in nicely and even the rear is helping to slow the plot down. Downward gearchanges are still something of a challenge, especially as I need to look at the gate to remind myself where the detents are, but leaving them as late as possible helps. The engine has developed a slight oil leak which will require attention at some stage but it can wait for the time being.

Feeling confident, I decided I would make an attempt at the RealClassic Compass Challenge. It was fairly easy to find appropriate places in suburban Brum - here they are.

Sunbeams were always known as the gentleman's motorcycle. Although I hesitate to apply this description to myself, the machine itself is indeed gentlemanly and I am so pleased I decided to tackle it.

Further Updates

I was still having a slight problem with the engine tightening up when worked hard, as well as the recurrence of the clutch slip problem, so took the Sunbeam off the road at the end of Summer 2016 to deal with these and other minor problems. When I removed the cylinder barrel again, I was pleased to see that there seemed to be plenty of oil around (I had been worried that the tightening up had been due to lack of lubrication) and that the bore was unmarked. There was however a slight scuff on the piston. When I measured the clearance of the piston in the bore, it was only around .004". Most of the reference material I could find suggested it should have been closer to .006" - .008" (a minimum of .0025" per inch of diameter is quoted in Radco's Vintage Motorcyclist's Workshop). So I decided to have four thou honed out. A local old-school engine reconditioner whom I've used in the past did this for me and I was very pleased with the result.

The slipping clutch posed something of a problem. The clutch is actuated by a pushrod through the mainshaft like many British bikes. The pushrod engages with a transverse pin which passes through a bored hole in the boss of the pressure plate (top left in the photo). This travels in a slot in the mainshaft to allow end to end movement.

I deduced that the pin was hanging up on the inner end of the slot hence not allowing full clamping pressure to be applied to the clutch plates. Bob Rodgerson came to my aid once again and bored a further hole some 5/16" further out to allow full travel of the pressure plate. On reassembly this seemed to have done the trick. Bob also happened to be selling his Tormach mini-lathe so I seized this opportunity to replace the Granville which had given good service but was really getting too long in the tooth for accurate work.

While the bike was up on the bench it was also a good opportunity to make a new exhaust retaining ring for the left side exhaust pipe - the existing one's threads were worn and it had only a nodding acquaintance with the stub on the head. This gave me the opportunity to use the Tormach for a job which is always tricky - large internal threads, without the opportunity to try the mating thread whilst in the lathe. The slots for the C spanner were cut by hand with hacksaw and file. I was very happy with the result:

I also needed to redo the gold lining on the petrol tank. I had foolishly used ordinary enamel for my first attempt and this had proved remarkably susceptible to being washed off by fuel. So I made a number of test pieces to check compatibility of gold paint and various lacquers including a petrol-proof version - eventually coming up with a viable combination. I do the lining by carefully using 3M 3mm flexible tape on either side of the desired line, followed by ordinary masking tape and newspaper to avoid any overspray. This works very well but it's always a tense moment removing the tape. Fortunately all was well, if not as beautiful as would have been achieved by the skilled painters at the Marston factory.

New corks for the Ewart petrol tap cured the minor weep I'd experienced earlier.

The slight oil leak was coming from the base of the timing cover where it forms the feed for the oil pump. This is a semi-wet sump engine, carrying the oil beneath the crankcase in an extension to it, as described earlier. The design of the timing cover joint to the oil tank is poor, with a very narrow flat on the oil tank for the timing cover to seal against. Of course, an oil leak at this point eventually results in the complete contents of the oil tank ending up on the floor. As with much else, the parts list is silent on how this was intended to be sealed.

Much work truing faces, building up with JB weld and manufacturing sealing washers from gasket paper and Viton sheet as well as judicious use of Wellseal and silicone has now given a true oil-tight seal, after many trial fittings. The timing cover is probably still the part of the bike I'm least happy about, but concentrated efforts have failed to turn up a replacement. It is however doing the job.

The future

I feel I have been successful in converting the proverbial sow's ear into, if not a silk purse, certainly a handsome and effective machine. There is little further to do to it, although of course a perfectionist would disagree! I have therefore decided to part with the Model 10 and look for a new challenge for 2017.

Here is a short video of the bike running on a local road (Webb's Lane):

Email me for a chat if you're interested........


This has been a challenging project, and my thanks go to:


I list below some of the sources for parts and materials whom I can recommend: