Modern Vespa

Hey all,

I have had to strip and clean my carb in my Vespa, all good...

Everything is back in place and starting fine.

I am struggling to get the bike running properly though, I have adjusted the fuel mixer slightly and the timing screw following some YouTube videos but unless I have the choke out slightly I can't seem to get it to run properly. I did have it running fine with the choke slightly out.

I have tried to adjust more so I don't need it out but when I use the accelerator it seems to flood it, causing it to almost stop... I can't seem to get it right and the mixer screw is the pain in the backside one that I had to bend a socket to adjust, it's a pain.

Any tips on the best way to do it?

Thanks.

You have an air leak somewhere and you are compensating with the choke. Something on reassembly didn't go right. Re-do it and make sure no gaskets were torn or out of place.

Mixture screw at the back should be 2.5 turns out from lightly seated. Idle adjuster should be whatever it needs to stay alive.

Thanks, any idea where the most common air leaks might be, I used all new gaskets and pretty sure it's all good, I took out the carb again as I had screwed the fuel mixer out too far...

I am going to screw that all the way in and then open 2.5 turns as you suggest and see how that does but any tips on where the air might be getting in massively appreciated

Most common leak spots are under the box, or under the carb, towards the rear bolt.

I goofed my last time and it was the gasket under the carb. I pulled the bolts and used a small pick to align the gasket a little better via the bolt holes in the carb. Then even back and forth, torquing on both so the carb sat flush and didn't warp.

Thanks will give that a go...