PROJECT CHIEF Road-ready and rideable

1 Oil is contained in the front half of the right side fuel tank; petrol helps keep the oil cool, but the drain plug is right over the cylinder head. Guess what goes wrong there...

2 ... yup, black oil all over the engine. I find a flat tray that fits between the tank and the head (after removing the spark plug) works best. A hole in the far corner can drain into a funnel below.

3 Awkward pic, but that’s the left-side crankcase seen from beneath. The crankcase drain bolt is the brass hex. It’s a taper thread, so it doesn’t need a washer – or overtightening!

4 The gearbox drain plug is on the bottom of the case. The oil is shared with the primary, so using a heavy gear oil can cause clutch slip. I was taught to use SAE 30.

5 Drain the residual oil in the primary using the plug at the bottom of the case. All of these – including the oil tank plug – are taper thread. PTFE tape can be used if they leak.

6 Gearbox/primary oil is replaced through the slotted cap on the top. The last Chiefs had separate gearbox and primary oils with a similar cap on the box top.

7 Dave’s box/primary took about a pint. Fill to the level plug, but leave the plug in as you fill; it takes time to get through to the gearbox and will escape from here as you pour.

8 With the oil tank replenished, once the engine is running, check for the oil pumping back through the scavenge pipe just under the filler cap.

9 Being a gear pump, sometimes it’s lazy and needs priming. With the engine still running, pump oil into the pipe from a can – it should very soon come spurting back up.

1 The seat is sprung on a sort of telescopic fork leg that runs through the frame. After removing a nut underneath, by the main stand, it can be withdrawn out of the frame.

2 Two or three short, tough springs are separated by spacers. Rate can be increased by winding up the nut, but we needed much more preload for a rider Dave’s size.

3 I made up some extra-length spacers on the lathe. Reduced ends locate the spring ends, keeping it in place so it doesn’t rub inside the frame and make groaning noises.

4 Assembled and ready to fit. It worked for my weight, but to carry a pillion Dave will need an external spring bar – two conventional saddle springs bolted to the frame.