Modern Vespa

Running without oil on the P200 engine.

Down the street to get gas and back again. Started to cut out. Figured any one of the many possible reasons. Fiddled with the screws. Seemed to run better.

Next day, rode about 1/4 mile to the hardware store, then decided to take it for a quick blast. Maybe another 1/4 mile. Sudden bogging at 40 mph uphill, but vaguely siezey. Puttered home real slow.

Looked at the autolube. Line was full but I had completely primed it when I put it away for the winter after rebuilding the autolube. Turned the mixture screw out a bunch. Normally, that would make it smoke like Bogart, but not a whiff of 2t.

Pulled off the carb box. Gasket was bone dry. Pulled the oil pump apart. Noticed a small witness mark on the sleeve. I had it clocked wrong when I put the screw back in that holds it. About 90* off. I knew it had to line up a certain way when I had put it back together. I was certain it was right. But obviously not.

Put it back together and hooked it up to the oil line. Held it upside down while spinning the pump drive. A definitive test. Every few turns it pushes out a slug of oil into the channel. Put it all back together and started it up. Obviously drawing oil through the line. It seems fine. Maybe I got lucky, but time will tell. Jeez.

Ouch.
Well… that's not as bad as just forgetting to put oil in the damn thing. I'm sure that's been done a few times.

Is it worth pulling the jug and inspecting the piston and bore?

I'm not sure what to do at this point. When I was riding, it felt like fuel related issues, but bad enough that I stopped fiddling with screws and went home.

It wasn't until I had a think that I started to suspect the autolube. Then like kicking myself because I put it together wrong even though I knew at the time what I was looking at and how it was supposed to go.

I suspect the cylinder has some new scrapes. Not sure I would even clean it up and rehone. The engine never got up to operating temperature. Seems to run the same. Compression feels the same when pressing the kick starter by hand.

When I rebuilt this engine, I did bearings, seals, cruciform, hone and new rings. Stock crank and p and c were totally salvageable annd owe me nothing. Figured I would get through my Vespa 101 teething with cheap rather than spendy parts.

I'm thinking maybe have a peek at the cylinder with the boroscope and just run it.

Thoughts?

I like your last comment - take out the plug and run a bore scope in there and take a look at what you got. Or if you have the time, just take off the head and run the piston down. The best would be to remove the cylinder, of course. But you can save that for last.

i don't suppose you can show in a picture somehow what you mis-clocked? having never had an autolube system, I'm curious what the mistake was.

This sleeve has three holes in it. Inlet, outlet and a blind hole. The inlet and outlet match up with holes in the pump body. The blind hole is where a set screw goes to hold the sleeve in place. If the inlet and outlet holes don't line up-no oil.

Here's where I went wrong. When you put the sleeve back into the body, pressure makes it hard to push the sleeve all the way to in. Somehow as I was pushing it in, the sleeve must have twisted. The solution is to keep pushing on the sleeve until the pressure bleeds off. Then you can line it up easily. Most people probably don't have this problem.

thanks for that, makes sense!

Probably hard for most people to get wrong, but I somehow managed to do it. I am often humbled by how I still get simple things wrong on these engines.

The downside of Vespa engines is how one little thing can bring everything to a screeching halt. It's also the upside. It's usually a small thing that you can figure out by thinking it through. And usually easy to fix.