Roxy: Mechanical Milestone

All right, so I did fix the brake lights earlier, but let's face it, that was an electrical issue (and a rather simple one at that).  This time we worked on the carb - perhaps not true "engine work", but certainly another significant baby step toward the goal of a complete engine overhaul!

During yesterday's ride, I noticed that problem again where she just wouldn't hold idle.  She was good for about 10 seconds before before stalling. I rode the whole loop through Golden Gate Park feeding her throttle the whole time.

I checked a couple of easy things that night.  Battery voltage was still good at 6.4V.  Also, I tried using the air and throttle screws to see if that did anything.  It barely had any effect.  Based on a lot of reading on the S90 group, that symptom pointed to a clog in the idle circuit.  (For reference, the screw settings were 2-1/4 out for air, and 3 full turns out for throttle).

So today, I actually opened the carb up.  Was a little nervous, despite having opened and dismantled the carbs on the other bikes dozens of times.  Again, it's different when you're working on the bike you actually ride versus one that just sits in place.


A reference shot of the screw settings.

The drain screw comes out.  After the gas had drained from the bowl, I realized that there was still plenty of gas left in the filter and I realized it was being held there by vacuum.  Next time I suppose I could run the engine with the petcock closed and thereby drain it completely.

Inside, the carb is actually nice and clean.

And here's the culprit, the slow jet.  I couldn't see daylight down the length when I first took it out.  Also noted that these are definitely not factory.  And they didn't even have a size on them.  I suppose it would be nice to clean up the original carb and get it back in, but then again, if this carb works with this engine, maybe there's no need to muck with it.

Pine Sol soak for a few minutes, followed by WD40 and then air.  While that was soaking I also checked the entire slow circuit by doing these 3 steps:
- with the air screw removed, shoot WD40 into the inlet and it should exit through the screw hole
- with the screw back in and the slow jet removed, shoot WD40 into the inlet and it should exit the slow jet hole
- cover the slow jet hole with your finger and shoot WD40 into the inlet and it should exit into the chamber

All back together, and then the moment of truth.  Took a couple of kicks to start her and I was sure I'd buggered something up.  But then she fired, and wouldn't you know it - SHE IDLED!

And in conclusion, don't run in Reserve unless you have to!!!  I think that's how it ended up clogging in the first place.