Modern Vespa

So it's been a while since I posted.

I've replaced the ignition, spark plug, lead, fuel hose (cut short as possible) and am stumped as to why the bike will not start.

It seems to be not pulling fuel from the carb. The float chamber is full but it seems the casing is not pulling a vacuum. It will run on brake cleen but cuts out as soon as the brake cleen is used up from the casing.

Amy ideas of the low hanging fruit I should start with?

Here's a shot from the automobile museum in Turin in advance payment to anyone with some suggestions.

Have dou tried to manually open the fuel tap?

That worked perfectly Leif. I opened the screw on the electronic valve at the carb and fuel started to flow. After that I chased down some air leaks and now it seems to run OK so it's down to the business of jetting.

Test ride with the biggest main jet I have.

https://youtube.com/shorts/LG2CkrQqOlk?si=D9yb51zVWidMUhA9

The carb slide is sticking and so I cannot evaluate if the idle jet is good so once I get a chance I will change the carb for an SI24 and then start the jetting again. I feel like I need richer idle and main jets as when I tried the richest main I could still rev it out on the stand.

Also mixed my fuel with a bit too much oil so it's a bit smokey, not great for break in but in the grand scheme of things I'm very happy with the little cosa.

The air leak was down to me loosing a washer from under one of the carb screws, turns out the boot is too long without the washers to clamp the carb down properly so I'm also pretty confident I've built an engine with no leaks but I will see about that when I have the new carb fitted.

I also fitted the rear carrier that came with it.



Will carry some saws but looks like I'll be short some space for the firewood. Maybe I'll just keep this one for going to the local shop.

Also on the fuel supply issue the electronic fuel supply solenoid on the carb seems to have been stuck. Once I took it off and refitted I seemed to have no fuel supply issues. I had been on a test spin and came back to find the manual tap had been closed. Must have just been stuck o rings.