I had a 1957 NH where the previous owner had filled the GB box with grease, just the same as he had done on his earlier Ariels. It worked perfectly well.

With an oil filter in the return line I have gone over 20,000 miles without checking the sludge traps. I know of people who have done much more than that but I don't know their frequency of oil changes, how clean the engine was inside when it was rebuilt, etc.

If the gearbox is for a 56 bike, then the 54 mainshaft will be the wrong length. The different lengths are fully explained in the Drags catalogue and under Gearbox in the Ariel 4-stroke part of their website. Someone will do you a straight swop, I would expect. The GB5 gearbox is the same as the GB6...

Go to your local bicycle shop and get one of theirs to mount on the handlebars. This is the cheapest and most accurate option. The problem you face with a speedo driven from the gearbox is that the PA type used prewar (and in 1946/7) have the drive at right angles to the case ie parallel to the face...

Charlie - I have sent you a private message.

I was working on a Mk I front crank today and, as is my practice, I put the crank into the parts washer and applied the pump hose to the drillings. These I make sure are scrupulously clean by means of a variety of tiny bottle brushes. Starting with the hose pumping cleaning solution in through one s...

I have a slightly worn sliding member, spring and cap (but no nuts) which would probably cope perfectly well with the power of the 250. You might get a better one at the AGM and I can take this one to the AGM for you so you can compare what is available. I don't have a spare valve lifter assembly bu...

That looks like one very modified engine. What was Grandad's intentions with it? Was he going to race it on methanol? Where are you based? If you can do, attend the forthcoming AGM autojumble where you will find many of the items you need but also a vast stock of knowledge to tap.

The cheapskate answer is to transfer carefully the timing marks on the two gear wheels to the other side of them and then put the gears on the other way round. The gear on the camshaft can be pressed off easily enough using a vice.

But new gears would always be a better option if you can find them.

The late Len Ore used to say that 75% of carburettor problems could be sorted out by attending to the magneto.