Saturday, November 21, 2009

Lean or Vapor Lock?

So, I braved the 3 mile journey into town to the gas station with the S7 Deluxe this morning.  It was a beautiful autumn day and I couldn't resist.  KYL95 started right up and purred along nicely down the road.  No popping, no carrying on, just reliable shaft power pushing me down the road to reach 11,900 miles.

I got a few quizzical glances while topping up.  It even started with a gentle kick for the journey home.  6 miles later I was still enjoying the wind on my face when I pulled in the driveway.

I figured I should take a quick glance around the machine and make sure no leaks or loose bolts were developing.  I let it sit for a few minutes and then figured I'd go out again!

That's when the trouble started.  She wouldn't start.  I had to put the strangler on, and then when I turned it off when the black smoke started, the engine would sputter and stall.  What's going on?  It ran fine for 6 miles and even up hill both ways!

I surmise that either the engine is simply running lean, or that the carb is vapor locking after sitting next to those hot exhaust pipes.  I coaxed it around the house and closed the garage door behind me.  Further investigation is required.  I can't believe that its running lean since when its relatively cold it runs great.  Its gotta be the heat off that exhaust header, even with the fiberglass exhaust wrap.  I wonder what I could use to insulate?  Maybe a piece of the exhaust wrap around the bowl and around the fuel line?

1 comment:

  1. I put a VW Beetle spark coil in and saved the original Lucas coil. The beetle coil is surely producing a stronger spark, but I don't think the original coil was at fault. I was still able to reproduce the sputtering after getting the engine good and hot. It ran fine until I turned the engine off and tried to restart it.

    I moved the carb needle up one notch to see if that improves it. It was too rainy today to take it out for a test. Maybe later this week. I have a feeling I'll be moving that carb needle back where it was. More testing is needed.

    I checked the ignition timing again. Set statically, the points open at TDC per the manual. When running and observing with a timing light the actual fire occurs a few degrees BTDC. Not sure if that's right or not.