Classic Motorcycle Mechanics



Our Pip ‘makes do and mends’!

Ihave a pal (yes, I know it’s a stretch) called Phil who’s take on life and things is a bit different to mine. He reckons that anything with a three-pin plug is not worth repairing if it malfunctio­ns.

Maybe because I’m a careful Christian (other deities are also tolerated) I don’t quite hold with that philosophy. My big telly jacked in last week. It’s 15 years old and although I’ve never fixed one in my life I thought, what’s the worst that can ’appen?

After half-an-hour on the mighty ‘choob’ it became apparent that there was a specific PCB with much logic and capacitors and such that just might cause the set to fail. Using our favourite auction site I located one of said items in question and bought it from a very helpful man hidden away in deepest, darkest Boltonia. The TV now works a treat (so far, fingers crossed!) and, I have to admit, I felt pretty good at the whole operation.

On the same day my pal Loz popped across with a Kawasaki generator cover; it had a leak from an internal (infernal more like) oilway. Could we mend it? I rated our chances at about 50/50, due to the location and the age of the cover. But, as before, what’s the worst. etc? I mounted it on my little miller and we exposed the oilway, then made a slim brass sleeve to fit into the orifice. By tapping the open end for a grub screw, the theory was that the sleeve should replicate the original failed oilway and the screw should block off the open end. With a bit of acetone and air to clean the plot we plonked it back together and Loz toddled off into the sunset. I still wasn’t 100% confident, but given the price of a new ’un, (eye-watering, let me tell you) we had to give it a shot.

As I answered the phone to Loz two days later I knew straight away that I’d failed... bugger! Whilst dramatical­ly reduced, it still had a tiny weep. I think that of all bike-related ailments, a persistent oil leak is about as welcome as a polecat at a picnic. But I’ve had many a problem that requires a bit of lateral thought, so time to get thinking.

NOS bits bought off ebay might make your bike look cute, but try riding it without piston rings because the manufactur­ers stopped making them 10 years ago, that’ll get your attention. But all is not lost; there’s always a way, honest.

Case in point, a bike for a friend a little while ago, the oil ring had failed in a big way and left the piston in a bit of a mess, no piston or rings was available for months, what to do? We tacked a piece of aluminium on to the piston crown and then welded up the damage to the ring lands. The reason we welded the chunk on the crown now becomes clear. With the piston nipped in the chuck of my dinky lathe (Chinese,nese not a workhorsew­orkhorse, but extremely accurate) I could clock up the piston for zero run out on the top land, then make a small centre drilling in the sacrificia­l lump to put a centre in. This ensured that the piston remained exactly central while it was being machined. I machined up the diameter first and then re-machined the grooves for some alternativ­e rings, finally removing the tack welds with a Dremel to free the lump. With the new rings installed normal service was resumed and the little bike returned to active use.

When things get really sticky, it’s time to get a bit lateral. My little Duke was burning oil like an old Foden a couple of moons ago, but time was marching on as only time can and I was getting desperate. I spun up a slender tube out of an old cast iron flange, about 3mm bigger diameter than the bore size, then parted the requisite ring width off the end. A bit of work with file and hacksaw and I had a manageable piston ring. Being cast iron, it bedded in pretty rapidly and very much to my surprise it functioned rather well for lots of miles. I figured that if it was good enough for my mate Soichiro, Mr Honda that is, it might do for me. Soichiro started off making piston rings, bless him. Mind you, he did get a bit carried away when he had to make oval ones for the NR! Fave quote from Mr. Honda: “Real happiness lies in the completion of work using your own brains and skills.”

 ??  ?? 1
1/ One mullered piston.
1 1/ One mullered piston.
 ??  ?? 3/ After surgery, with a new ring installed, ready to rock… 3
3/ After surgery, with a new ring installed, ready to rock… 3
 ??  ?? 2
2/ Fire up the TIG set, weld up the mess and add a chunk on top.
2 2/ Fire up the TIG set, weld up the mess and add a chunk on top.

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