First Start of the DOHC 250

As I mentioned in a previous blog, starting a rebuilt bike for the first time can be a slightly nervous moment. That was particularly true for bikes such as the AJcette and the AJS V-Twin for which the engine was created rather than rebuilt – you simply don’t know if it’s going to run or, worst case scenario, lock-up and break something.

The DOHC 250 produced that same feeling of trepidation and I was very conscious of what was inside the engine – rebuilt crankshaft (modified MOV flywheels and “K” main-shafts), a one-off “top-end” held together with eccentric studs and enough gears in the cambox to construct a gearbox. You may recall what it looks like….

….all driven by bevel gears through home-made Oldham couplings. Plus, a completely revised lubrication system using quills strategically positioned at all of the important parts of the engine.

However, before hitting the “start” button for the rollers there was one final thing to do (apart from filling the oil tank and gearbox with oil) and that was to set up the fuel level by adjusting the float chamber height. The fuel level on the downdraft Amal RN carburettor

should be just below the level of where the jet (the needle jet) is in the airstream. The brass plug is a pretty good reference point and so a length of clear tubing was attached where the fuel feed pipe to the carburettor exits the float chamber and the height of the float chamber adjusted accordingly, shown below.

So, it was now time for the first start…..

I was very happy with that - nothing broke and it sounded pretty healthy. Considering how much is whirring around inside there is also very little mechanical noise. There is a small oil leak to fix but for a first run this is a good result.

Although I haven’t started any road testing yet (these bikes are physically rather small for me or, conversely, I’m rather tall for them), this is a major milestone where, after 3 ½ years, the builds of both KTTs and the DOHC 250 are complete and they are all running. Road testing, however, will be postponed for a while as we seem to be back to windy and rainy weather as winter approaches.