ASP FS61AR reassembled and running nicely

We are all on coronavirus lock-down and like many, I am keeping myself busy in my workshop with hobby-related projects. I’ve several kits on the go which I’ll post up in due course. Thankfully the shops are still processing online orders so getting hold of workshop items has been unaffected – indeed some shops are posting up notes stating demand has been staggering which can only stand them in good stead when things return to normal. For second-hand eBay is also still going strong which brings me to today’s subject.

I recently finished a book on the history of motorcycles in which the author touched briefly on how early riders in Australia approached the maintenance and repair of motorcycles. Spare parts were not forthcoming – sometimes taking months to arrive and were more than likely prohibitively expensive. So, ever practical, the early Australian riders either made do and mend, or if a part was absolutely beyond all hope of repair (i.e. knackered) then a ‘she’ll do the job’ part was knocked out on amateur lathes. Now my reading happened to coincide with the arrival of an ASP 61 four stroke engine from eBay which, advertised as locked up and non-running, I’d bought at a quite reasonable price for spares.

One ASP FS61AR Four Stroke displaying signs of careless handling and a ‘dipped in toffee’ look.

The previous owner had described ominous clicking noises when attempting to turn it over. It also had that ‘dipped in toffee’ look indicative of caster oil and a perhaps less-than-careful previous owner. I expected the clicking to be valve damage and sure enough my first suspicions were only raised as the front face of the prop driver was heavily worn. The kind of damage that would happen if, say, the prop was to let go….

Still the carb and exhaust were fine which is all I had really wanted from it. Curiosity made me delve further and that’s when things become puzzling. Under the cylinder head the valves were fine. The piston was certainly shot, and the cylinder head, near the glow plug hole, had signs of metal particle impact. The glow threads also looked a little worn. I can only assume that a glow plug, perhaps too loose, broke up. That doesn’t explain the prop driver of course so the true story is likely to remain a mystery.

Fully stripped down and cleaned up I set about wondering “what would the aforementioned Australian’s do?” Was she salvageable?

Engine parts layed out following a good clean to remove all that nasty castor oil. The bearings were smooth enough so despite the handling it’s suffered I don’t think it’s actually had many hours run time.

Curious damage to glow threads, combustion chamber, prop driver and piston. Yet those valves seats were fine and the marks on the pistion didn’t line up with the poppets.  Was the damage terminal though?

Methylated spirit-tight so presumably air-tight…..

So, taking stock, piston; shot but they are cheap enough. Liner; no damage at all. It’s ringed so, unlike an ABC engine, the liner doesn’t really need replacing when changing the piston. Cylinder head assembly: well they are more that the engine’s worth to replace. But was the damage beyond that Aussie-style make do and mend? To a mechanic I’m sure the thought of using any part below par is anathema but thinking about those valves I wondered if perhaps those chips weren’t so bad as to stop it running. A quick tightening of a glow plug revealed the threads were solid enough. Reassembling the valves, I applied methylated spirit to the combustion chamber to check the valve seals for leaks. Nothing leaked though so they were fine.

I took the plunge and ordered a new piston. Once reassembled I bolted it to my test stand and took it outside (remembering to observe social distancing of course!).

All’s well that ends well. Purring away nicely on a 12×6 prop