Latest toy (was, but see next page for yet another Enfield)                                                          December 2016

1912 Royal Enfield 345cc v twin prototype

I responded to an advert in Old Bike Mart in July 2016, and bought the project you see here. After seeing the photos from the seller, I decided that the bike was unique, probably a prototype. I crammed a LOT of internet research in, and I'm confident it dates to 1912. Being a long term Enfield nut (I once heard it said "only the nicest people ride Enfields"), I had a copy of Peter Hartley's 1981 book The Story of Royal Enfield Motorcycles, and on the inside title page was a photo of this engine (or a very close relative) in a Brooklands racing bike - that put my mind into overdrive!

104 years old, a "one off", and even in this day and age, it still surfaced as a low key advert, from an owner who didn't really know what he had in his possession. Thankfully, my gamble/initial research paid off and I'm confident I have something more than a little bit special.

The bike/parts originally belonged to Ivor Mutton (Ivor was the VMCC marque specialist for Royal Enfield for many years, and was the creator of The VMCC's Banbury Run). Strangely, some time after Ivor died the parts you see were disposed of by his daughter, but for some reason the petrol and oil tanks went a different route (discovered later).

I have seen various documents written by Ivor, and he mentioned that "I have an early 1912 example, reputed to have been raced at Brooklands". Personally, I think the engine may well have been, but the frame is different (see Racing Days below).

Standard 1912 RE 345cc v twin                December 2016

1912 2 speed model 160

This is the standard road bike of 345cc of 1912. I include mention of it here to show the differences to the prototype bike. It uses a Motosacoche engine with side valves and truly horizontal cylinder finning (parallel with the petrol tank frame tubes). The fuel tank contains both petrol and oil compartments in the one structure. The Bosch magneto is low down, behind the engine. It is clamped to a twin tube section of the frame. The bike could (theoretically) be started with a handle on to a pair of 'dogs' cut into the drive sprocket of the rear chain. Practically, the footboard on that side would have to be hinged out of the way, and the engine rotated at a fair lick whilst holding handlebar mounted exhaust valve lifter, then dropping valves when engine rotating. Quite a balancing exercise! Another method is to put the bike on the stand, engage 1st gear, and (mindful of getting dragged into the wheel/chain) pull on the back wheel. Or just run and jump!

Developments                                              December 2016

1912 345cc v twin prototype. Nickname "The Green Monster"

By late October I had tracked down the ORIGINAL petrol tanks (2) and oil tank, and reunited them with the bike. The correct model of magneto had been found, and also a suitable saddle. The front fork blades were part of the original purchase.

You may notice the frame is very similar to the standard model, but has 4 brackets for the petrol tanks, has a bracket for the high mounted magneto, and is single large diameter tube where the magneto mounts on the standard bike.

The engine is Royal Enfield's own manufacure, of 54mm bore x 75mm stroke, and the valve layout is overhead inlet valve, side exhaust valve (ioe). In 1911, 1912 and 1913 Royal Enfield went racing, entering the 1911 and 1913 Junior TTs (at the Isle of Man), and also events at Brooklands race circuit.


Racing days                                                December 2016

Bert Colver and 345cc racer 14th Sept 1912

This is a photo of Bert Colver at Brooklands in September of 1912. Note the similarities between his and my bike. The fundamental difference is the steering head angle, so I can't claim that I have Bert's bike!

Try as I might, I can't find any mention of this early engine being used by any other rider than Bert in 1912 - and I've spent a LOT of time looking through The Motor Cycle and Motorcycling magazines of 1911-1913, as well as various archives.

Incidentally, there is a mis-captioned copy of this photo in Peter Hartley's "The Story of Royal Enfield Motorcycles" that claims this bike as being 1911. This Enfield engine wasn't designed/in use until 1912 (see later updates for proof).

Enfield did go racing in 1913 to the Isle of Man, but the engines of this type were in the later frame, and had gained the glass oil tank. Interestingly, the racers were still 345cc, entered in the Junior race, whilst the road bike (the 3hp twin) was 425cc. It is likely the 345cc version was sleeved down, as photos show crankcases with a bulge at the base of the cylinders on the primary drive side (a feature of the 425cc cases).

The magneto also moved to the front of the engine, which meant that the petrol tank could be one piece, full length, of greater capacity (which would be a distinct advantage in a lengthy TT race)

July 1911 Isle of Man Junior TT             December 2016

August 1911 Brooklands report


I have also come across a photo of Bert in the 1911 Junior TT using a Motosacoche engined bike, but I can only use via an 'embed' method, which can't be done on this site. If you wish to view, open the url below in a new tab or window. It can be found at:

Suffice to say, if the TT bike of July 1911 had a Motosacoche engine, then the Brooklands bike of August the same year would also be Motosacoche engined! The attached magazine article and photo (no. 13) to the right confirms this.

It is always very easy to identify a Motosacoche engined bike of this type, even in a poor image from magazines of the time, just look for the 'W' shaped inlet manifold linking the centrally-placed carburettor to the inlet valves (on the outside of the vee cylinders).

Looking for a Royal Enfield Oil Can              January 2017

1912 Royal Enfield Motor Engine Oil

This is a page out of the 1912 Royal Enfield List of Spare Parts and Accessories for the 2 3/4hp model 160. Enfield marketed their own brand of engine oil back then, and I'm trying to locate a can. It came in a 2 pint size. If you know anyone with one of these tins, please get in touch.

Two bikes are better than one                      January 2017

Front hub, components of rear cush hub, brake pedal shafts, front brake components and bracket for 2 speed gear thrust bracket.

The other 1912 bike is now rubbing shoulders with the Bullet in the garage. The prototype project has immediately taken a huge step forward, as I now have all the missing parts available to copy/remanufacture.

Being a tight Yorkshireman, ordinarily I wouldn't have been able to justify the cost of this kind of investment, but circumstances came good, and it became possible so I jumped at it. We're all only here for a set length of time, we don't know when the off switch will be flicked, and I want to get as many projects complete and into use as possible.

So, the front spool hub that came with the Green Monster had the correct number of spoke holes, but seemed too short for the space between the fork legs. Comparing it to the other bike, it is exactly the same. The fork legs need more pulling in than I originally thought.

I had a couple of nickel plated shafts come with the prototype (visible in the Green Monster photo laid on the boards just behind the oil tank), hadn't a clue what they were. I now know one of them is the rear brake pedal mount. I think the other may be a different version of same (I've seen the rear brake pedal mounted both to front and rear of engine, so maybe slightly different shafts).


After the prototype........                                 January 2017

Pre production 3hp twin

 This is the first mock up of the 1913 3hp twin of 425cc. The cylinder bore has been increased from 54mm to 60mm. It has the same engine type as the prototype, being of Enfield's own manufacture, but housed in the early frame. When the bike entered the catalogued range for the 1913 season, it had a new frame and slightly heavier constructed forks. Interestingly, although this frame is like mine, the glass oil tank of the 1913 bike has already replaced the steel tank. The later frame has a dropped seat position, resulting in a different shape to the petrol tank.

The article highlights the "ahead of it's time" oil recirculation system.

Period photos - 1913 TT (maybe?)               January 2017

Maurice Down 1913 TT

I've kindly been sent some interesting contemporary photos by John Seymour. We can't be certain when/where they were taken, but after a bit of detective work, I believe they were taken at the Isle of Man TT in 1913. From TT records, I discovered that C Maurice Down only competed in one Junior TT (1913). The same year, Bert Colver was there on an Enfield (AB 1483 - a photo of Bert with the bike can be found at,1,4,2-3-0-0-0-1-1-TSC-HK4S0YC.html).

Enfield TT workshop 1913?                           January 2017

Workshop photo of AB 1483 and AR 1955

 Here is a photo of both bikes in a workshop (both registration numbers visible in original photos). Could this be the Enfield support team?

A fantastic photo (my laptop wallpaper)            Feb 2017

Bert Colver with race transport

This is Bert Colver (seen at Brooklands earlier) with his 345cc racer on the sidecar plank, possibly on his way to Brooklands)? Good to see he's using a 6hp Enfield as the motive force. Note the standard doctor's bag behind the front wheel, no doubt full of tools and maybe a packed lunch?

Take a close look at the shape of that bulb horn - I want one of those.

I found this and a few others in the Ivor Mutton collection - I think it's an absolute gem!

The 1911 Royal Enfield bulb horn!              February 2017

Accessories page from 1911 catalogue

Found a better view of the horn in all it's glory. Would be interesting to know if this was actually made by Enfield, or an accessory supplier.

Another interesting item is the "wallet" - I hadn't noticed this when going through the pages previously. The frames at this time all had a curved top tube that braced the steering head, and the wallet fitted in the gap between the curved top rail and the petrol tank. In case you can't read the inscription on the body, it reads "Brooks" so was made by the firm better known for bicycle and motorcycle saddles.

I've never seen one of these.

For 1911 there was also a standard fitment toolbag (assumed as also leather construction) fitted in the space between the rear mudguard, rear number plate, and rear carrier. In 1912 and after, there were 2 steel/leather toolboxes mounted either side of the rear carrier.


First announcement of the new 345cc engine                                                                            February 2017

1912 First disclosure of Colver using new Enfield twin engine

"A New Engine"

Just discovered! Buried in the August 29th 1912 edition of The Motor Cycle, the very first mention of the new engine being tested/ridden by HV (Bert) Colver (centre column). Refers to Bert being "seen on the track with it a month ago". This also appears to be the erroneous source of the often quoted "outside flywheel". There can be no mistaking that this is the first Enfield designed/manufactured v twin engine, as the clear reference to the overhead inlet valve (all the other twins at this time were side valve inlet and exhaust). Unfortunately, there is no record of it having achieved 60 mph at or around this time. Indeed a Douglas 350 twin, with steel cylinders managed to clock 73 mph in late Nov 1912, possibly in the same Class B record attempt that Bert was supposed to take part in. Better things were to come in 1913, both at Brooklands and the Isle of Man TT.

More vintage and veteran motorcycles to come.

New tinware                                                            April 2017

New rear chainguard

New rear chainguard copied from other 1912 bike. All soldered construction, as it would have been when new. Mounting brackets omitted, will sort them when time comes to mount it to the bike.

Getting the shape right                                          April 2017

Cross sectional shaping

Difficult to show, but the shaping of the chainguard isn't just a plain inverted 'U' shape. The backbone curve is separate to the sides, with a lap joint producing a definite step. The side pieces were bent over to double thickness at the joint to create a sufficient step to look correct. The solder filled in and smoothed out the final profile. Cross joint also visible to facilitate front shaping (not present in original, but they were being made by the hundreds, possibly thousands, over formers, rather than one-offs)!

Late 1912 advert, relating to the Olympia Show and the 1913 model range

Handbuilt by humans                                            June 2017

4 scribed marks for the valve alignment and line boring of the seatings for the bushes

I decided it was time to look inside the engine, as it was obvious from the outside that some work was needed to the crankcases, and at the least, bearings would probably need renewing. The barrel and head are all one piece, as was the practice at the time. The inlet valve is housed in a separate removable assembly (a bit like a valve rocker box), that splits from the head by a bayonet 'peg and twist' lock arrangement, together with a screwed lockring. This type of fixing was also used on the 3hp twin in 1913, altered April 1914.

Lifting both barrels off revealed one scored barrel (tricky, as the cylinder walls are only about 3mm thick), and ALUMINIUM pistons.

Removing and dismantling the external automatic recirculating oil pump revealed 2 gear wheel operation (again carried over to the early 3hp twin). However, it also features an oil feed to the base of the front cylinder, a feature that only carried over onto the 345cc racers, and the 3hp TT Replica.

Inside the timing chest, after removing the cam wheels and followers, original 1912 scribing and alignment marks can be seen setting out the valve gear! Hopefully the photo shows sufficient detail.

The drive side main bearing retaining plate is held in place by 6 screws. Each of these has the head crossdrilled (racing practice) with a tiny hole so that all can be wired in place. We're definitely into prototype territory here.

Unfortunately, the scribing/alignment is offset to the bush housings, so boring out is also off-centre and a few have cracked when the bushes were pressed in. The hole to top left of photo was for a screw to hold the bush in place! Will consider welding crack, and using Loctite with a new, non press fit bush.

Aluminium repair needed                                    June 2017

Cracking evident to base of crankcase. Just out of shot to top, lug broken off. White mottled area just above threaded hole is where other lug should be.

The crankcases are connected to the frame in 3 places, 2 front and rear towards the top, and one central down at the bottom. The bottom fixing is by a lug sticking down from each crankcase half, with a frame lug trapped between (possibly with removeable spacers). On one side the crankcase lug has disappeared altogether, on the otherside it has broken above the bolt hole. In addition, the root of the lug on one side has exerted too much leverage on the crankcase, and cracks are evident. I suspect it has been overtightened without spacers in place to limit to force.

Good Guess                                                           June 2017

Inlet manifold turns out to be a perfect fit

It's Banbury time again, and as well as 500 pre 1931 motorbikes to ogle, there is an autojumble with some stalls seen nowhere else. It's an early start from Yorkshire (on the road for 6am), but it's usually worth it. This year didn't disappoint, with a few bits coming back to Yorkshire with me.

So, I'm shuffling through a box of bits and came across an inlet manifold that I think I've seen before. The owner thinks it is possibly flat twin, Douglas or Wooler but doesn't think it's vee twin, I've got a different view (call it an educated guess rather than a sure thing), but we agree a price, and it comes home. Following day, it's out to the workshop, assemble all the castings, and it fits like a glove! Threads are perfectly aligned, and now that I've checked all the 100 year old photos, it was fitted to the 3hp twin in 1913 and 1914.

Not totally original for the 1912 prototype, but too good to pass up.

Similar photo, a 100 years earlier                      June 2017

Inlet manifold on a 1914 3hp twin engine

Here's a photo of a 1914 3hp 425cc engine that appeared in some publicity material at the time. Although the overhead valve housing has changed in appearance, the inlet manifold must have stuck in my mind. I will probably make a replica of the original Y shaped manifold in the fullness of time, but this is a good find, and will suit my purposes for now. Now I just need to complete the valve gear (missing inlet push rods, exhaust valve spring collets, seatings and springs, and exhaust valve lifters) and find a veteran Amac carburettor (or better still, a CAP carb). In 1912 Amac produced a float chamber with a feed pipe to the carb body that was shaped similar to a eukulele, so I know what I'm looking for.

Note that the position of the spark plug seatings on this engine is in the side of each cylinder barrel, between the inlet and exhaust valves, almost facing each other. The prototype engine has the spark plugs directly above the piston, dead centre in the top of the barrel.

Frustration                                                               July 2017

2 3/4hp forks left, 3hp forks to right. Height between spindles is similar, angle of camera to subject must have been different.

Back in November, I toddled down to Birmingham, and took advantage of the free entry day to examine, photograph, draw and dimension parts of Enfield twins. Whilst everyone else was slowly circulating the bikes on show with comments such as "Ooh" and "I bet that's worth a few bob", I was shuffling the bikes about as much as I could, and laid under them where necessary (I was the subject of quite a few odd looks). It just so happens they have a 1913 (maybe) 345/350 experimental ohv v twin, a 1914 3hp/425 ioe v twin, and a 345 ioe racer from 1914 (with later frame).

As my front forks weren't complete, I spent quite a bit of time on the dimensional differences between the 2 3/4hp/345 ohv experimental twin (same cycle parts as my bike) and the 3 hp twin. What I didn't do when I came back, was compare my fork blades with the information gathered. Now that I have looked at the fork blades, compared them to the 2 3/4hp standard bike and dug out the notes from Birmingham, I now find I have a pair of 3hp fork blades!

This is frustrating, as they are wider than the earlier model (tyre size larger on the 3hp twin). This now clarifies why the front hub seemed too short - it was. So I have the correct front hub, but the wrong fork blades. I could probably modify the fork blades to slim them down, but it will mean ripping them apart, making new parts, and brazing back together. I'll try advertising for a swop first. Damn! Can't imagine that there will be many people with spares laying around.

Petrol tanks and fittings                                       July 2017

Petrol tanks with one through the tank fitting removed

I was asked by Leon if I thought the petrol tanks on this bike were the real thing, or some that the previous owner Ivor Mutton had made.

I'm going to stick my neck out, and say that I think they are OF THE TIME (ie 1912 rather than 1950s-80s). Photo alongside shows tanks in a bit more detail. This is how they came to me, painted and with fittings re-nickeled. Because they are of the time, chances are they are original, but after 105 years, who can say - unless a photo emerges from under some dusty shelf somewhere (I think I've done pretty well at finding most of those)!

The boss near the top of the upper tank is for securing the 2 speed gear selector shaft.

1912 Tank fittings                                                   July 2017

Close up of fuel filter etc (left) and dismantled Davisons sight glass

In the course of my research, I spent many hours reading/scanning through copies of the Motor Cycle magazine between 1911 and 1913. These have been digitised by Boston Public Library (USA) - a link can be found on the Useful Links page. An advert that cropped up repeatedly was Davisons - manufacturers of petrol tanks and fittings.

The sight glass to the right is a Davisons item - why not Enfield? - because Davison patented it! The little nickel plated top contains the patent reference, so that is something else to research in an idle moment. The sight glass unit is a pressed brass pocket, that was soldered to the tank side, there is an inlet at the bottom (just visible in the bottom of the slot in the tank) and an air hole in the cap. The glass tube was clamped (carefully) with sealing washers by the brass gland nut-I'll get some ethanol resistant O rings for that job.

I'm still working out the item I've removed and laid on the upper tank. In place, it has a built in fuel filter inside the tank. Remove the small top cap and the whole thing is retracted from below. Whether it is just an elaborate fuel filter, or has some regulating function, I'm not sure. The tube is hollow, all the way, and there are 3 cross holes visible low down through the gauze. I suspect once opened, there will be a tendency for the little nickel cap to disappear into the nearest hedge, unless a retaining wire is used.

When zoomed in, Bert's bike at Brooklands clearly has both caps open by a few threads.

A few more bits and pieces                                  July 2017

Bits 'n bobs

Back from Founder's Day Rally at Stanford Hall near Rugby - another 6am kick off - with a bit more contraband. Strangely, everything this time is for the 1912 project bike.

From the left:

Seized 2 speed gear (currently immersed in cola in an attempt to remove the rust)

2 speed gear quadrant bracket

13 engine shaft shock absorber springs - I'm 1 short for the set of 12 as the bike came, so this batch completes the set, and gives me a spare set - couldn't have worked it better!

A pair of original Fibrax/asbestos brake blocks (probably not correct for the bike, but can be made to fit)

A replica veteran brake/exhaust valve lifter lever to go with earlier one I picked up at Beaulieu last September.

A 2 speed gear rack shaft (it's the larger vee twin size 6hp or maybe a small v twin with a kickstarter), correct diameter and teeth - too long for my bikes, but could be modified.

The 5 items to the right came from Dave who is restoring a 3hp/425cc vee twin from 1913.

The front fork top clip is correct for the project bike, so I swopped for a stirrup brake horseshoe that I had for the 3hp. The push rod, 2 x exhaust valve lifters and 1 x lifter lever are all on loan for copying. The blue thing dangling over one of the valve lifters is the neck strap for my camera!

A whim...............                                                   Aug 2017

1912 Brooklands members badge set

OK, you'll have to forgive me this little foible. I recently found out that speed merchants at Brooklands could buy Members badges on an annual basis, which gave them (and a couple of guests) free entry to the circuit - obviously money well spent if you were a frequent attendee. With the project bike having an association with Brooklands, particularly in 1912, I went looking for a set.......

They are not cheap, but I managed to swing a reasonable deal on the set in the photo. Complete in their 105 year old presentation box (with member number stated on front of box, and stamped into reverse of all badges).

As I was looking for these, it became obvious that people try to collect the whole span of badges, from 1907? to 1942? - I think I'll resist that temptation, but I can see the appeal.

A second Bosch magneto                                  Aug 2017

I recently made a successful bid on a Bosch DA1V magneto on the dreaded ebay. It was very reasonable money, but was a gamble, as the top plate was missing so the seller didn't know what angle twin it suited.

When it arrived I got the steel wool out after spotting some letters/numerals stamped on the steel core. Should have thought a bit more about that, it took me ages to clean all the steel wool fragments off the magnet! It came up as 60 degrees, so that turned out lucky! I then inspected the cam block housing and realised that this had the correct blocks marked I and II as the manual said it should. The other mag I bought last year turns out to have a non original cam housing/cam blocks. NOTE If anyone wants a copy of the original BOSCH manual (in English) contact me. The nice people at Bosch archive supplied me with a digital copy FOC.

So can I use the new mag to provide sparks to the prototype? Not that easy, as the drive is by a spade end to the shaft (whereas the prototype needs a tapered shaft for a sprocket). It turns out the new mag is exactly the correct type for the model 160 road bike, which has a drive shaft coming out of the rear of the engine that the spade end engages with. Shame, I didn't need a spare for that particularly.

Looking further into the shape of the steel core, and the body it is only just clearing as it rotates, reveals quite different shaping, so it may come down to welding up the spade, and reprofiling it to a taper for a sprocket drive. One thing is sure, if that happens, the winding will need renewing, along with the condenser.

Couple of DA1V mags, with internal detail and angle stampings shown on rhs photo.

More autojumble finds                                       Sept 2017

Not much found this time, despite it being a full on weekend at Netley Eurojumble on the Friday and Beaulieu on the Saturday. Then the long haul back to Yorkshire on the Sunday.

Everything bought at Netley this time, Beaulieu a complete blank! Picked up a collection of 1912 Amac carbs that I'm hoping to build one good carb out of. Also a 12 tooth magneto sprocket for the Bosch magneto (smaller taper shaft than later mags). Last item was an ML magneto for one of the New Hudsons, in pretty ropey condition, but it has a special feature found only on the New Hudson, so if they appear, I grab them!

I went to Beaulieu dressed the part this time, a photo of a Bosch magneto with advance/retard lever on my chest, and a composite of pictures about the early v twin girder forks on my back. A couple of leads re the magneto lever to follow up, but no contact on the forks.

Did meet up with Dave again though, and relieved him of more of his 3hp bike so that I can use it as patterns for copying! I've also got his rotted out rear brake rim (which turns out to be the same as on the model 160 road bike), so I'll be approaching a local firm to see if I can get 2 copies made. Good job I waited until I got the 160, as the profile I was going to copy (from a bike in the Birmingham museum) is different. With Dave's and my 160 being the same, I'm confident this is the correct profile.

Is this unusual?                                                    Nov 2017

Don't know if this is a standard feature on engines of this age - a ring of lead pressed into each flywheel.

Hand built features                                              Nov 2017

Another feature of a handbuilt engine - oil grooves hand cut with a chisel - the number of hammer blows can clearly be seen as "steps" on the grooves.

"At speed" Nov 1912                                            Nov 2017

Brooklands Nov 1912

Not a very clear photo, but still worth including here. This was late Nov 1912. Bert was attempting to break a couple of records on the 345cc bike.

Note: this was common practice at the time, riders made more money from sponsors if they successfully created a new record, so that the manufacturers could make the most of publicity exposure.

This was the same week that Enfield's managing director JW Davis died.

The attempt was unsuccessful due to a freezing carburettor/manifold (it doesn't look a particularly warm day for a long distance record attempt).

The caption on the photo declares Bert was "all out" at the time, I would love to know what speed the bike achieved during the attempt, but I suppose I'll never know.

The attempt was overshadowed by a high speed attempt by a 350cc Douglas, which achieved 73mph.

Do you want more?

If you want to continue the story..........