Wednesday 4 August 2021

Completion of the Dry Build …the last little odds and sods

Most of the work has now been completed on the dry build of the bike but, even when you think you are close to finishing, there always remain lots of little jobs that need completing. This particular blog is about some of these “little" jobs.

Having now got a tank with which I was happy there is now the job of fixing the tank and seat to the frame. The original AJS V-Twin had no rear mudguard and the seat is positioned very low and aligned with the back of the tank. It is difficult to achieve the same appearance with a rear mudguard and also if a spring seat is used because both raise the seat height. I have ridden a vintage bike – girder forks and a solid “rear end” without  a sprung seat – not through choice – one of the seat springs on one of my bikes broke when out for a run. It is not really a pleasant experience riding a vintage motorcycle effectively sitting on the back mudguard on English back roads strewn with potholes and ruts and, although I want my AJS V-Twin to replicate the original as far as possible, I also want to be able to ride it with at least the minimal comfort that seat springs can provide.

I went through my collection of available seats but the only one that fitted the bill was a lovely small leather seat ….but it was designed to be used with no springs. Luckily, my good buddy John Taylor had a lovely small sprung saddle in his collection that fitted the bill perfectly. I positioned my new Indian-made tank and the small sprung seat on the bike to see how they would fit.

On the original, the tank is little more “wedge-shaped” – like a slice of cheese and the front of the seat is at the same height as the back of the tank

but this is probably about as close as I can get with the constraints of a rear mudguard and a seat with springs.

The next task was to fix these securely to the frame. At the front of the tank, I made 2 steel bosses and tack welded these to the steering head; they will be brazed when the bike is stripped. At the rear, a post that fitted into the frame tube was fabricated

to support both the tank and seat. As on the original bike, the rear of the seat was supported by “uprights” that were fixed to the frame tubes and the underside seat frame was remade to avoid fouling the mudguard. The original is on the right and the new one on the left in the picture below.


For the first time, I was able to see the bike as a complete entity with the tank and seat properly fixed.


Incidentally, the tank is rubber mounted at both the front and the rear.

I had postponed one final detail of the cambox lubrication until the tank had been fitted, namely the fitting of oil primers, because I did not know how much space would be available below the tank; it turned out there was not much!

I therefore made a couple of simple knurled screws that thread into the top of the flow restrictor support pillars and take up a minimal amount of space

These will be used to prime the cam chamber with oil and ensure that the cams dip into oil on first startup if the bike had been laid up for some period of time.

The next job was to start making cables. As I have mentioned in previous blogs, I buy most of my cabling bits and pieces – inners, outers and ferrules from CarrotCycles because I found that they can provide cable outers + ferrules that properly fit period levers.

For both the throttle and the valve lifter cables, a one-into-two junction box is required and I use those used on Vincent twins and supplied by the Vincent Owners Club. They are simple, well made and don’t look out of place on a bike such as this.

However, they are fairly heavy (compared to the cable) and simple aluminium brackets were made to support the junction boxes on both the valve lifter

and throttle cables.

There is a small brass block silver soldered to the bottom of the petrol tank to support the throttle cable junction box bracket.

The nipples on the front brake cable are silver soldered for extra strength. The clutch cable will be made during the final build as an adjuster needs to be threaded into one of the rear footrest support plates.

Both the kickstart and the gear lever needed a bit of tailoring to fit the bike. A couple of bends were put into the gear lever to clear the rear section of the timing case

and the long Triumph kickstart (an ebay find) was cut-and-shut to remove approximately 1 3/8”

As with many of the vintage bikes that I have rebuilt and ridden I have found that the riding position needs to have the seat positioned a little further back for a tall rider and the easiest way to achieve this without spoiling the appearance of the bike is to add a bum pad.

Whilst the original World Speed Record attempt bike never had a bum pad fitted, because I plan to be able to ride this bike on the road (hence the addition of a number plate) I need to be able to somehow sit astride it.

And before someone asks “how is your foot going to reach the gear lever?” ….it won’t. It will be a positive stop hand change, like a kind of early paddle shift. Luckily, I have long arms.

There are still a number of small fettling jobs to do when the bike is stripped - a couple of small holes in the engine plates to support the crankcase suction filter and engine breather are required, to complete the welding or brazing of parts that have been tacked onto the frame - the front tank support lugs and the reat brake anchor and, of course, to check that the front forks are OK. The girder fork blades are in excellent condition but they will probably need re-spindling and the condition of the steering head bearings needs checking. 


No comments:

Post a Comment