Hi,
I've had a garage load of Mark bits for years, and always meant to do something with them - well you know how it is. Recently the Club Registrar mailed me with a note saying there was an 'irregularlity' in the records of one of my Douglases, and he inadvertantly gave me the clue that solved a long-standing mystery about what I bought a dozen years ago as a rather tasty Mk1, apparently the only survivor of the three 'Land's End Trial' bikes prepared by the factory in 1948.
But it had no frame number, and there were two rear-subframe mounting points - one pair is the Mk1-type ear lugs, but the other was a pair of drilled bosses at the bottom, where the later MK4/5 sub-frame mounts were located. So I assumed it was a factory replacement frame of around 1949 - one that would do for earlier models as well as later ones.
But now I hear that it is in fact a Mk3 frame, despite the very early T35/S/308 engine. Obviously, I need to put it back into a genuine Mk1 frame, along with most of the rest of the original bits - my project for the next few months.
The question was, what to do with the Mk3 frame - that's a hard one, eh? So I rooted around in my workshop and built the frame up to a full bike out of my spares collection - pretty well a new Douglas. And since it's a new bike, I decided to put it together as a Special - after 50 years with standard(ish) Marks, here was the chance I'd always wanted as a lad to make something different and personal. There are several out-and-out Specials in the Club in the UK, so it's not such an outlandish reaction - this would simply be a late addition to the efforst of a small group of odd-ball engineers and their unusual (or in Neville's case, occasionally rather weird!) machines.
So here she is!
The engine is - at the moment at least - a much modified Mk5 unit that I've been playing with for a few years. The Carbs are Amal Concentric MkIIs - 28mm diameter throats, to replace the tiny 19mm Amals fitted as standard. The inlets are bored 24mm - as large as they can go, with taper-bored aluminium spacers to match them up to the heads. The compression ratio is 9:1 - I shortened the barrels for this - and there is a pair of Suzuki GS650 62mm pistons fitted with 2-3 thou bore clearances. These are much lighter and stronger than the standard Douglas ones, and there is still plenty of room for the valves (even with the No.3 ('almost Plus') cams fitted) despite the valve head cut-out being the 'wrong way round'.
The front brake is a Plus unit that I got, already severely chopped about, from a grass-track racer. Since the Plus fork reaction link is mounted higher than that on the Marks, I've put in a new anchor bolt to keep the link parallel with the swinging arm, and used the original reaction pivot boss to convert the brake to twin - um, twin . . . er, well, fully floating shoes! This way, there is no nodding motion on the front mudguard whenever the forks move up and down, so the stays don't break on very rough roads any more!
Oh yes - and it DOES stop, too.
Most of the non-standard fittings are in stainless (I HATE RUST!). The wheels are WM2 x 19" front and WM3 X 19" rear (stainless rims and spokes, of course!). Electrics are all 12 volt positive earth (dynamo converted for 12 v output, elctronic regulator). The seat unit/tool box is made from the door of my old fridge - recycling is supposed to be good for us, so I'm told! That tank is a 4 gallon fibreglass job I got at an autojumble for 45 quid - with an interesting hole in the side, since fixed. The Monza filler cap alone is worth the price of the whole tank!
With a rebuilt magneto she starts first time, runs like a turbine up to around 7500 rpm (maybe more, hence the rev. counter that I'm still trying to connect to the motor), and has a performance well into the 'Plus' range. And she's not a thirsty beast either - I get around 90 miles per UK gallon knocking around the district and up to 100 mpg on runs - yes, really! Those carbs make all the difference - got 'em for twenty quid from a breaker who said, "No-one wants them old things now!"
So, if you don't mind the odd Special occasionally, this one's my effort at the breed. Makes a change, anyway . . .
Cheers
Doug
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