2 Sperry Rand Tricubs - restoration project thread

Mini Bike & Go-Kart Parts

Engine for Unit A rebuild complete and first start today. Linked video is after only about 10 min fiddling with carb settings.


I'll finish the cosmetic work on this then start the Unit B engine rebuild.

Now... how to I get this thread moved to the "Trikes" forum?
Freshly rebuilt and accurately trimmed engine for unit A... now on to the unit B engine. Hopefully 2nd engine goes as smoothly as the 1st.

Overdue update on this project…

The unit B, original engine has been fully disassembled and inspected. Sadly the rod journal on the crank was badly scored and corresponding bearing surface of the rod was trashed. This was clearly not the 1st time this engine had been apart. I also noted that the oil splasher was missing from the rod bolt and no evidence of any remnants in the case. The cylinder bore and piston look pretty good, so light honing and new rings should do the trick there. An NOS rod and a barely used replacement crank have been acquired, so reassembly should begin soon.

Also, the tins for this engine are back from the sandblaster and the replacement body has been recovered from OH and safely in my custody.

Slow, steady steps, men. Slow, steady steps.
So back on this project again. 2nd engine (unit B) reassembled now with new crank, rod, rings, lapped valves, honed cyl, coil, points, condenser, rebuilt carb, etc. This engine required a lot more love than unit A engine. Nice bright spark now, so hopefully I can find time to fire it up this weekend.

The Tricub parts book shows an exhaust support bracket secured by a hose clamp around the muffler. No evidence of this part was apparent on this original engine, except for the spacer and longer bolt on the sump cover. During the initial start of the unit A engine, I also discovered that this bracket is probably a good idea since the 90º exhaust elbow had loosened considerably (jam nut was fully tightened) after brief operation and I was barely able to get another full turn on those NPT threads. Anyway this is the diagram from the parts book showing the bracket…

And this is the bracket that I fabricated to replace it (x2).

I have not found any reference to this part in any B&S parts catalog, so it may have been added by SPD during final assembly of the vehicle.

If all goes ok with the start-up, I'll be ready to paint this engine and get both installed on their rolling frames. At that time I can finalize wiring, throttle and choke cable lengths. I also need to come up with a support for the choke cable... again nothing was apparent for this function during disassembly.
Well guys… more delays on this project timeline due to a freak tornado or microburst that took out about 30 of my trees in early June. This damaged my shop roof, barn roof, spring house roof, totaled my hay wagon, but miraculously, no damage to the house. The saddest damage was to my vintage Sperry Stow-a-way storage hut.

But even as bad as this looks, it pretty much popped back into shape after the tree was removed. It will still take some resin and glass work, but not too bad considering the 45 year-old fiberglass.

The insurance settlement was satisfactory so $-wise all is pretty good, but you can never get the lost time back. This is why I never put deadlines on my projects.

Anyway, I did manage to get unit B engine back together and started. I have it pretty well dialed in, but now looks like issue with the float valve, so carb needs to come apart again before I can finish dressing this engine.
Progress report… Admittedly not much done on this project for past few months, but the 2nd engine is now fully rebuilt, dialed in, painted and trimmed. So the twin engines are finally ready to go.

I have unit A engine installed and I am working on wiring layout, choke and throttle cable layouts. I need to design and make brackets for the choke cable support since there was no evidence of anything on the original engine and I can’t see enough detail on the old, original photos. This bracket was apparently SPD part, not Briggs because nothing shown in any Briggs parts breakdown that I can find.

Between the original harness from unit B (heavily butchered) and layout on the unit, I have come up with a pretty good reproduction of the original harness. I have created a plywood template so that I can duplicate this harness for the 2nd unit, plus any future needs. I was able to find the original type cloth wire loom. I was also able to find NOS Briggs wires for the charging and lighting circuits with correct terminals to connect to the engine.
I’ve been on and off this project for a while and I know it is long overdue for an update…
Unit A chassis has been fully assembled with engine, clutch, belt, brakes, choke cable, throttle cable, wiring harness, battery, fuel tank, etc. The engine has been starting and running under its own fuel and electrical system for the 1st time.

Unit B chassis is on the lift table and is not far behind.

Now for the bodywork. Even with the replacement body that I acquired last year to replace the abused body on unit B, I have decided to go ahead and repair the original body. This has taken some time, but I am making good progress. There were 18 extra holes drilled by a previous owner that needed to be filled, plus the choke pull mounting hole was greatly oversized which needed filled and then redrilled to proper size. There was some significant damage on RH side and rear that had bad repair work and needed to be un-repaired and redone. The front corners of the body had been rounded off pretty aggressively, so this needed built back up and reshaped.

The unit A body is in pretty nice shape, but still required a couple of erroneous holes to be filled and some cracks repaired. Anyway, both bodies have had the major stuff addressed and I’m mostly down to smoothing the color side surface. I have found a local boat repair guy who will spray the gelcoat for me and he has had color matched. He’s ready as soon as I deliver the bodies to him.

Stay tuned...