Black Ariel Little End

[James Hickman]

I'm replacing the piston on my 1929 Model B. The gudgeon pin is a bit loose in the little end bush. It slides in very easily and there is a barely perceptible "rock" when it is in place, although no discernible up and down movement. I can (just) slide a 0.0015" feeler in alongside it. Replacing the little end bush would be a pain. Drags don't stock them (Part number A6/249, AKA 1130-28). Would have to get one made (unless anyone knows where they are available). I'm no engineer - happy to try basic lathe work, but it's not just just a bronze ring, it has a spiral oil channel in it so would not be easy for me to make. Presumably then I'd have to ream it (or get it reamed) to a correct fit. I'm tempted to just reassemble - will I get away with it?

[paul.jameson]

It all depends on how many miles you are going to do. If your plan is to ride from the UK to India, or across the USA, then replace the bush now. If you are going to do 250 miles per year, leave well alone. As we are just coming up to starting to ride again and you have difficulty in obtaining a bush at present, why not leave it alone for the summer and consider replacing the bush come next winter? You may well find that no discernible wear has taken place meanwhile.

[Simon.Gardiner]

James - seems to me you've got an almost perfect fit!
Little-end isn't highly loaded and you don't really want it to be tight - I can't resist a quote from 'Tuning for Speed', I do like Phil Irving's way with words:
'The small end bush for racing must not have less than 0.001" clearance, but more can be allowed without detriment except for the noise caused. Nortons can be permitted up to 0.005".....'

SG

[nevhunter]

.001' is minimum SAFE clearance. New bushes sometimes close in a bit after getting hot a few times. .0015 is fine. Make sure the rod is aligned. Nev

[James Hickman]

Thanks both. Advice much appreciated as ever.