Monday, March 21, 2011

Dia de Los Vespino pt.1

This weekend was full of cooking out, drinking beer, playing lawn games riding and wrenching on mopeds. Here's Sean and Neal playing ladder golf.

The most exciting news however was that I worked out the ignition problems in the Vespino! While checking for spark we noticed that it was sort of weak and orange in color. By Responsible John's recommendation I tried to adjust the coils a little bit so that they would run a little closer to the inside of the flywheel. After adjusting and readjusting I got them set just a little closer. We also used an existing timing mark on the stator and lined it up with the edge of one of the bolt holes. You can see the timing mark by the right screw...

This was a stab in the dark that paid off because the bike fired right up! I got to ride it down the street a little bit. The Metrakit seems like it has some good potential and feels a lot like the Puch kits. The circuit pipe that I have didn't really let me get up too fast (nor does the 14/12 carb). I still have a lot of tuning to do. Gabe took some video of the maiden voyage which he's editing together and I'll post up soon.

I still have issues however. The rear clutch is constantly engaged and kills the bike when trying to idle. After taking the clutch bell apart, reviewing diagrams, etc. I had an idea. Nate and Mark thought that I was missing a piece that holds the start clutch arms together mostly due to this image...

This photo makes it look like there's a piece that the little arms connect with...But I really dont't think there's anything missing.

Here's my take on the Vespino clutch:
1. It's a poorly designed system. It has two little spring like tabs that force the clutch out inside of the bell.
(picture from
2. It works as a "slip clutch". It's always engaged, but when the bike slows its allowed to slip backwards as the clutch bell spins. This means that when you try to push the bike forward its engaged; you can move it backwards with no problem...but forward is hard work.
3. However at idle or very low rpm's it doesn't know what to do, so it occasionally grabs and kills the engine.
4. With this in mind I realized the function of the bicycle mode. The original design for the vespino had a separate throttle on the left side that you twisted to engage bike-mode. This is necessary as it disengages the clutch and allows the engine to idle at a stop.

I tested this theory last night and was finally able to get the bike to idle. Because I was starting the bike without the decomp lever, I just used that cable and lever for the bike-mode.

All it all it was an awesome day. So glad to get this thing at least starting. Still needs work though. Venga!

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