Interesting Technique

[Spokes]

Before I say what I tried, I have to tell a story.
This is about my CA160 build, but it should work on a CA95 and perhaps any old engine.
My 3rd CA160 was a real mess. I imagine it sat outside, in the midwest for 30 years. Rusty, filthy, grimey. The engine was stuck, the points cover was missing and even the advance was rusted on the cam. Three decades of mud wasp nests, caked oil, rodent eaten wires...the mac daddy of wasted. My idea of a perfect project bike.

While rebuilding the bike, I decide to just service the engine, clean it up and out. I filled the cylinders with PB Blaster and worked the pistons loose, filled the engine with fresh oil before removing the side covers to clean the sludge and to service the clutch. I salvaged the starter, which was packed with rust tight, salvaged the carb and rebuilt it, took the engine to the plant and steam cleaned it,(boiler steam pressure rules) then painted it.
She sits today as below.


Time to start the engine. Timing, points, coil, carb all set. Can't start the engine. So, I check the compression, 50lbs. Oh well. So here is what makes this story an interesting technique.

For kicks and grins (and knowing I have nothing to lose) I add maybe 1/2 oz. of motor oil in each cylinder, replace the plugs and hit the starter. She fires right up! The engine burns no oil and runs strong. I have put a few miles on her and the carb needs some adjustment as I have retrofitted an external throttle, but otherwise the engine runs perfect.

This is the first time I have tried this. Maybe someone out there who can't get the old bike running can try this "interesting technique"

[ByTheLake]

I love these stories. Gotta take a stab at this, walking it through in my pea brain.

So, it's given that we start with 50 PSI. You didn't say whether that was one cylinder or two cylinders, so I'll assume it was roughly 50 PSI for both cylinders. Should we make an assumption that the mechanic followed proper procedure and wasn't on some summit in the Himalayas when taking the measurements? Ok, we'll assume proper procedure was followed. (sorry, couldn't resist).

We also know that you added .5 ounce (which is one tablespoon) of oil per cylinder. Let's see ... that will lubricate, seal, and consume space. At TDC, there's not a lot of room between the valves and the piston crown, so the oil could boost compression a bit, at least until it's pushed out the valves.

I'm discounting the fact that the oil consumed space and affected compression temporarily. I'm guessing that the lubrication and sealing aspects of the oil were key factors.

If both cylinders were similarly low in compression, I'll assume it wasn't a stuck valve or some carbon deposits. I will guess at this scenario:

Rings were stuck in the grooves: Could the oil have sealed the cylinder walls enough to build compression sufficiently to break the rings loose again, allowing them to expand to the cylinder walls under compression again? If the engine sat in the elements as long as you suspect it did, the rings and grooves could have accumulated corrosion.

That's the best I can come up with.

Putting it another way, the proof below explains the logic.

[grubsie]

By the Lake.... You went through an awful long explanation of how this engine was able to run when the answer was quite simple. You and the other members simply need to look at your formula more closely. It's actually right in front of you. Can't believe that you missed it. Hopefully most of the other members already know this. Approx 4 lines up from the bottom, almost in the middle of the line. Don't even need the rest of the formula.

E.<K>=<U>-1/2MW;A'

So simple really.

Also a shout out to you Spokes. You do "Sick" work. My next project after my Benly is a '66 CA160. Gonna do my best, but that shot of your engine is going to keep me awake nights. Especially where the previous owner painted the engine, carb and wheels/hubs in flat black while everything was still on the bike. Also rattle canned white on the body, shocks etc in the same fashion. I get tired just looking at it. Sigh!

[Spokes]

No longer available

[ByTheLake]

If nothing else, your experience is a testament to the durability of these Honda designs. If that engine can endure what it's been through and still run, just imagine how dependable these engines should be if they're taken care of and have regular oil changes.

Thanks for sharing the experience, Spokes.

[Jetblackchemist]

Done.