1959 Triumph 'Twenty One'

Engine and wheel restoration


    Some time ago I sold my Honda CD175 Sloper to a chap who delivers heating oil here in Orkney and during the conversations about the bike he asked if I might be able to help with the restoration of a very old Triumph 21.  It might be very old to him but I remember when they were new!  Apparently this is an Orkney bike with a BS four digit number and was bought new in 1959 by the present owner's Father in Westray - an Island just to the North of the Orkney Mainland.

    Some time passed before the unit construction engine and gearbox arrived at my workshop, together with the rather rusty oil tank and the 2 wheels.  It certainly was a sorry mess and appeared to have been stored in a typical old Orkney shed and time had certainly not been kind to it.  Kenny and I took the parts along to a local farmer who let us use his steam cleaner to see if we could remove some of the 50 odd years worth of crud which was well stuck to everything.  I didn't bother to try to prevent the ingress of water as I would be stripping it as soon as it was reasonably clean anyway and no further damage could result from this rather barbaric act; surprisingly, it came up better than expected and the wheels were given similar treatment followed by a liberal spraying with WD40 and Ferrosol - a Bilt Hamber product.

    I made a crude engine stand from MDF and ply so that I could have a stable platform and clamped it to my hydraulic bike bench so that it was at a reasonable working height and wouldn't dance all over the place when trying to undo it all.

    I'm not sure if there has been much (read any!) maintenance done on this bike in its 60 year history - the oil was like molasses and it appears to have suffered the 'black death'; I'll see better when and if I can get inside the thing.  It still had the original cross head screws in all the cases which, despite the steam clean were still virtually smooth headed with bonded on crap.  I had to scrape and poke each one to get to a place where a hardened phillips bit would fit well.  I had been spraying and tapping with a brass punch over a week or so to try to ensure I could get them out and eventually succeeded with every one.  Someone had attempted to drill the head off one of the gearbox lower outer cover screws, fortunately without any damage to the casing and once the others were removed I could slide the casing off the butchered one and that too screwed out just with fingers.  As is often the case with screws like this, they are not seized by the thread but by the larger diameter head.  There was evidence of a fair amount of butchery on various parts of the casings, fortunately most of it will dress out, which can be really time consuming.

Looks a bit like someone has had a screwdriver between the cases here - I'll have to sort that to prevent oil leaks!

More marks needing attention!


Quite a few bad marks around the kick start spindle hole

    Internally things looked a lot better, even badly burnt oil is better than none at all for preservation, although perhaps only marginally!  The rocker boxes and cylinder head came off without too much of a struggle and only one small piece of one top fin is missing.  I have dressed that up so that it looks more like standard.  There was a fair amount of rust in the barrels above the pistons but a small amount of diesel left in there for a week soon loosened that and left the motor free to turn over.  Next off were the barrels (no fin damage on those, just plenty of rust), followed by the pistons with completely stuck rings but I think the pistons themselves might live on yet.


    All of the drive side components came away easily, as did the contents of the gearbox.  The oil pump looks excellent as do all of the timing chest components. 

    No chipped teeth on the cam gears and the cams themselves are near perfect.

    The crank, however is another story.  You might be already aware that the oil is fed from the timing side, into the first big end, then through the flywheel sludge trap and into the drive side big end.  With little or no maintenance when the sludge trap is blocked with debris, the drive side big end becomes starved of oil.  The timing side big end and shells were near perfect but the drive side was badly scored and the shells worn almost to nothing.  This engine must have been shouting at the top of it's voice to be allowed to die quietly with no more suffering.

Looks like something has happened with the clutch, with this witness mark on the inside of the primary chain case.

    Some residual evidence of the 'black death'


    I took the crank along to Precision Engine Services in Inverness on our way to Grantown on Spey for a short break just before Christmas and they have managed to eliminate all of the damage at only 20 thou undersize and shells are available at that size.  The alloy castings have been cleaned and bead blasted, so with shells, rings, gaskets and seals I should be on the homeward reassembly straight fairly soon.  I can zinc plate some of the external fixings but quite a few bolt heads are too far gone to be used again.

    I'll add a bit more as things (hopefully) progress.

Casing blasted

Front Wheel strip and rebuild

Back to Main Page