Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Stubborn start M3W

Mark, I believe the engine has S&S “ease start” cams, which slightly open exhaust valves and reduce compression to allow for easier starting (until the engine is running), so probably the compression test is completely off. Does you car have an immobilizer?

Yes, compression tests on this engine would be meaningless. You can do a cylinder leak down test (which is really more useful) by ensuring the valves are both closed on the tested cylinder.

Seems to me the H-D mechanic should have known this, and that it's not a "Harley" motor.

Could the “ease start” cams have morphed into “no start” cams?

Based on another recent thread on TalkMorgan: Check out the O2 sensors. A crudded up sensor could negatively impact starting, but once hot might work well enough for the engine to run normally.

It can happen, but then it would not be running at all, as you’ll have no compression

Thanks. I don't know anything about an immobilizer. I can't find a mention of one. I found a mouse nesting in the boot this morning. That pretty much says immobilized to me.
Is it the governor that prevents starting when the gas is depressed? It's got that.
I'm searching for some guidance on checking the O2 sensor.

Mark, it’s a device that reads a chip in your key to enable starting. You probably do not have it, as you never had to mess with it.

I had a pair of used o2 sensors, can borrow them to you in case you wanna run a quick test.

Another idea, try to start it with the gas cap open (and open the spring-loaded valve in the filler’s neck).

This is very perplexing, so here’s my “out of the box” theory -

The engine sees higher rotational speed on a push start so the easy start cams no longer reduce compression and the engine starts, alternatively turning over on the starter at c 400 rpm the cams cause the compression to be too low to ignite the mix. There may be a background reduction in compression from another cause that compounds the problem when combined with the easy start cams?

How do I check o2 sensors?