C15 Specials

Trails riders have always sought to have a competitive edge and so frames have been manufactured separately to improve on the 'run of the mill' BSA frames. For instance the trials rider was quite happy with the rigid frame until a rider of no notability beat one of the top riders on a swinging arm AJS, this led to all the manufacturers changing. Some were just frame modifications and others complete redesign and manufacture. The most common was to lower the seat height and increase ground clearance. The engines were generally tuned stock models.

Jani Siikamäki

This is my 1964 C15S special. My first plan was install Norton 400 Electra engine into this BSA C15S frame, but when I got the frame from States I thought it is in too good a condition to cut up and make changes to to take the Norton engine. Soon after that I sold my matchless G15CSR 1969 and this gave me some money to spend on bits. The c15 engine was from 1963 and it was in very poor condition so I set out to make some changes and to build a special. I changed all the bearings and bushes and put in a new clutch. Then I had the cylinder bored out and fitted a new piston (Triumph Daytona 500 - 70mm dia); the cylinder head was next with a bigger intake valve and stiffer springs an also some polishing work with inlet port. I lightened the rockers and fitted a bigger carburettor with a 30mm choke; but I could not find a C15S distributor engine cam anywhere, so at present I still have a standard C15 cam. It goes and feels marvelous but I need little more power.

Fitting 35mm Ceriani forks at the front feels good and Falconetti MX shocks were very good at rear. I also put an A65 rear hub with a Morad alloy 18" rim and stainless spokes; these were fitted with Trelleborg Ten Masters tyres which give incredible bite! I also put a Wassell gas tank and saddle on the bike and some old Husky handlebars with Magura ISDT levers, plus a Doherty fast throttle. At the front I put a 21" Zundapp front wheel with the C15 brake plate (because I had lost the original one or maybe sold it?) and the footpegs are from Suzuki DR600 and the front mudguard is 70's. The bike was red but I have painted it olive green with a black frame. The rear fender is from Finnish moped call Tunturi Tiger and it is fitted back to front. The exhaust header pipe is C15S early model because I liked it and it looks better to me; the muffler is a custom plus a cocktail shaker and an old mopeds heat grill - I have some other gas tank options which I can try out if I get in the mood. This should give many trouble free miles for anybody!!!!!

(Click on the pictures to enlarge)

Best regards: Jani Siikamäki - Helsinki, Finland

Thanks for a superior c15 site with fine tips and stories & cool pictures !!!!!

John Seddon's C15 with Wassell frame.

The bike is a c15 trials with a C15F engine in a Wassell frame (no. w2164mx), with metal profiles forks. Metal Profiles of Wolverhampton was housed in the same factory as DMW who manufactured motorcycles, while Metal Profiles manufactured Forks and Hubs for many lightweight models of the early sixties, such as the Cotton and Ambassador.

Ted Wassell of Walsall left the Fleet Air Arm after the war and started manufacturing motorcycle components in 1956. Eventually in 1971 to 1975 he made complete bikes, but before then he did manufacture frames. The C15F engine being one of the latter models has most of the problems ironed out and dates it between 1965/66.

Jason Lovell
I have just brought a BSA C15T 250 cc trials bike and having a lot of fun on it too. It has many modifications done to the bike oil in the frame conversion and high compression piston etc. It has been ridden in many UK trials and won a lot of cups and trophies in the competitions. Last time it was ridden in a trial it was by a well known trials rider and he won the competition out rite. It has been to France and Belgium too where the previous owner had a 2nd 3rd and a 4th in these trials abroad.

Robert Hutchinson
I bought a c15t yesterday on an impulse. I have had a few trials bikes in the past but fell in love with this one. However the history is vague. Jim Susan frame apparently N0. C15 49659, (1966?) Engine C15G2105 (1967?), Motoplat ignition, Trials ratios, sports cams, it goes very well and will lift the wheel in 3rd ( 1st 3rd gears are low then a jump to top).

Tim Mathias

I thought that I would take some time to explain the features of my model C15T. The engine is stock 1961 although everything has been blueprinted and upgraded where possible, typical being the Alpha conversion for the timing side of the engine. The frame is however the real matter of interest. The original vendor, Commerfords of London, must have produced limited numbers of this model from available parts. The frame consists of a standard C15 swinging arm connected to an oil in tube special. It's not the later '71 OIF model but rather a true special! The reservoir starts at the headstock and continues to the swinging-arm where the in-line filter exists to feed the engine in conventional style. The frame number is 3500 so you might presume that other models exist ? Well to date I have not seen another, - perhaps you may be able to enlighten on the matter?

Commerfords of London used to manufacture frames for Speedway machines

I'm now starting to add bits to the frame.

Authors Notes are coloured red for clarity.

Mike Green (USA)

Here are some photo's of my bike that won me 16 championships!

BSA WCBR-C15MX

Check out West Coast British Racing

Oct 1995, AHRMA National MX, Holister Hills, CA.
Premier Lightweight start. No.21 Mike Green on the WCBR-BSA C15MX leads No.3D Brian O'Connor on WCBR-Ducati 250SCR. Mike won!

Tommyville GP 1997, Premier Class Winner. Mike Green on the WCBR-BSA C15MX

December 1998, Tommyville GP, Sandhill Ranch (Brentwood, California):

Mike Green aboard the WCBR-BSA C15MX (250cc) that he's raced for MANY years finishes 3rd overall and 1st "Premier" class (pre-1965). Dick Mann won overall on a DMS B50MX.

The C15MX after an AHRMA National MX at Sandhill Ranch, Brentwood, California in 1992; who says it doesn't rain here? The bike won, but... we had to drag it out of the truck the next day! Nothing moved, not even the engine. We stripped it 100% and found sand (the track really is sand, add water and you have grinding paste) in the cylinder, brakes, cables, swinging-arm pivot, etc. It ruined the bike! We rebuilt it in 2 weeks time and won both motos!

BSA WCBR-C15T
My C15T a replica, I built this in 1994 (if I remember right). As you can see it uses and early B44 frame, this has been modified. The back bone was cut, then the down tube was heated - a bar in the head-stock allow leverage, thus changing the steering head angle. The backbone was then heated and pushed down level with the remainder of the backbone; a spacer was cut and welded in place (approx 1.5"). Montesa Cota clamps/forks/wheel where then fitted.
The engine was stripped 100% and we started over. Crank was polished, as were all bits inside and out. A late B25 piston was used with the "T" cylinder-head thus lowering the compressions to something like 7:1. A "T" spec cam was used and a 626 Amal. The tick-over is great! I can roll up to a section, and while I'm off looking it over the BSA will just sit there and idle away. First time out I think I won (was a while ago). The other C15 we use to race with Eric Tucker at the same "muddy" Sandhill event. Eric raced a C15 in CVRG (California Vintage Racing Group -pre AHRMA) MX from 1984 onwards, winning a number of races and Championships. In 1988 we built my C15MX, thus had 2 C15s out there (Dick Mann's made 3).

BSA WCBR-B40MX (Ex-C15MX)
Later we'd build a blistering fast B40 engine (bottom pic) and Eric went after and took the AMRMA-West 500cc Premier Intermediate Championship with it. The B40 was sold nearly 3 years ago and has since won more races and championships! The No.22 BSA with Eric Tucker at Sandhill Ranch... is powered by a B40 and he won the 500cc race that day!

The WCBR-B40 was a fun project. Built in the early 1990's to replace the aging C15 engine in the No.22 machine (ridden by Eric Tucker). Under CVRG/AHRMA rules "all modifications must be period"; meaning: an early B40 can compete in the Premier 500 class (pre-65), while a later Square B40 has to compete in Classic 500 (post-65 to 70). With that in mind we began with a Round Barrel B40 engine. We had two things in mind; More BHP and strengthen the gearbox. With our own blue-print in hand we put the cases into the mill and moved the gearbox output bearing hole .250", then bored the L/S bushing hole to take a needle... a B44 gear set was then fitted. The crank was lightened (a lot!), then re-balanced to suit. The inside of the cases were polished, as was the outside. A custom MegaCycle cam and B40SS followers were fitted. A B44 alloy cylinder was shortened to suit the B40 engine, a 9.5:1 Hepolite was fitted. The head was ported/polished and big valves fitted. A special intake manifold held a 932 Amal. Primary was all lightened and alloy clutch fitted. 428 sprockets/chain was used on the final drive. Ignition was stock points with a MityMax battery eliminator. The engine had great power, revved to the moon (for a B40), throttle response was: "twist the throttle and the rear tire reacted immediately!" Best of all it was FAST and dependable and won races!

Mike winning Moto 1 Angles Camp March 2003

Bryan Lambert

Here's my Grass-Track Hagon BSA C15. It has a roller bearing big-end with 12:1 compression and runs on Methanol. The ignition is a Boyer Bransden unit.

James Middleton

Thought you would like to see my class-winning C15 trials bike. This is used regularly in Lincolnshire, in 'Poachers' trial events (www.poacherspre65trials.co.uk).

The machine has a C15SS engine, using a triumph piston giving a displacement of around 282cc. The frame has a modified C15 front diamond, heavily modified bantam rear diamond, modified Triumph Cub swinging arm, cub hubs and modified heavyweight Triumph forks. The bike is running an extremely special ignition system, consisting of two components! (no points, no condenser, no boyer type magnetic pickup) and can be obtained from £5. Takes a week or so to fit, but once done is very reliable!

I could write pages on this bike, if anyone is interested in any other aspect of the machine, they could email me.

The contents of these pages are for your reference and while care has been taken to ensure authenticity no liability can be accepted by the author.

Why not visit www.amputee.me.uk