Kickstarting a Velocette comes with a bit of myth but by following the procedure in the factory red owner’s manual, starting from cold has proved to be straightforward – first kick in fact. However, starting when the engine is hot is a different matter.
Coupled with that and possibly related, again when hot, the engine revs are slow to drop when closing the throttle. There’s nothing immediately obvious but clearly, an investigation is required.
So, I ordered the correct carb service kit from Burlen, plus a new main jet, needle jet, needle and pilot jet. Amazingly (well, to me at least) Burlen had all this in stock – for a 60-year-old motorcycle – and delivered them next day.
First thing was to take the petrol tank off to gain access to the carburettor, an Amal 389 Monobloc. But to get the tank off, you first have to remove the seat, which appeared to be held on with a through bolt at the front and at the rear by a bolt also holding the rear suspension mount in place.
Bear in mind this is the first British motorcycle I’ve done any work on since the early 1970s, and most of those were old nails at the time, so I’m finding my way around the Velocette at the moment. Working out what spanners or sockets work where, and how best to operate them.
I’ve also found that my odd collection of Imperial size spanners and sockets are just that – odd. Mostly AF sizes as it turns out and not fitting anything. What does work are a few BSW spanners and sockets, and I can feel a trip to Machine Mart coming on.
Seat off, tank off (dropping the rear under-tank tie strap in the process, which finished up wedged between gearbox and primary drive, ho hum) and immediately one problem is evident. Both the choke cable and the throttle cable exit the top of the carburettor at awkward angles – enough to cause the sticking throttle. New cables are on order and I study the layout to see how the exit angle can be improved – probably by modifying a rubber mounting block that the tank sits on.
At the same time the cable operating the exhaust valve lifter is touching the cylinder head which can’t be right. Check through photos of other Velocettes and two methods of keeping the cable off the cylinder head appear. One uses a metal cable carrier that turns through 90 degrees and the other is a spring wrapped around the cable.
Let’s just take out the plug while I’m here, much easier with the tank off. Wow. Not only is it black and full of carbon, indicating a rich mixture, but it’s also a very modern NGK Iridium BPR 7EIX with a tiny centre electrode. I have a new spark plug, an NGK B8ES which is the closest match to the originals for a standard Venom. It has a conventional centre electrode and is also slightly hotter running than the B7.
While I’m waiting for the new cables I’m going to strip down the carburettor, check the jet sizes and replace with the new ones which are the exact spec for this year of Venom.
