Vespa bogging, jetting advice please

[stellp]

Hi guys im new to the forum and would like some advice as i dont know much about these scooters.
I brought a vespa 90 Douglas thats been restored with a 125cc cylinder and a SHBC 19.19 carb the trouble im having is it has a weak idle and bogs mid range badly and feels lean at full throttle. Iv brought it without a airfilter will this make alot of difference?
The carb had #42 idle, #60 atomiser jet and #72 main and iv gone up too #45 idle and #85 main just as a base jet because when riden with the choke on it rides better and a 19mm carb is bigger then the stock 16mm carbs for a 125 so iv up jetted it abit but the engine isnt reacting how i would expect. Thats why i ask you guys what would you try next.
I have checked for air leaks at the inlet and carb this is fine now iv sorted those.

[jbcollier]

Fit the stock air filter first. It makes a huge difference.

[stellp]

Apr 30, 2021 13:28:19 GMT jbcollier said:

Fit the stock air filter first. It makes a huge difference.

Really thanks ok iv got one on order.
So how would you enrichen the mid range fuelling on these carbs as im used too needles and this carb doesnt have one?

Also how do you guys check your crank seals for airleaks as thats somthing i havnt done?

Thanks

[jbcollier]

You can change the atomizer to change the mid-range but it is very seldom done. Usually you dial in the main and that's it.

I use a Motion Pro vacuum tester but it easy to make up your own. Get round expanding rubber plugs from a hardware store (plumbing section) to fit the intake (carb removed and exhaust (muffler removed but stub pipe/elbow still in place. On one of the plugs fit an auto valve stem. Use a bicycle pump to pressurize the cases to no more than 10 psi. Spray soapy water all over and see what you find. Should hold pressure for at least 5 minutes. Longer is better but that's long enough.

[stellp]

Thats what i was thinking i know there quite commonly used and couldnt see people changing atomisers and sliders all the time so i must be missing somthing ill try the air filter when it gets here.

Ok i did make one aswel when i used to build auto engines years ago ill see if iv still got it somwhere, i take it you cant get access to them while its running to squirt some brake cleaner around them?

Wheres best to find info on striping engines/scooters down as there are definitely some components on it fitted wrong like i dont think there should be a roll pin on the gear selector or its the wrong size because it has too much play.

[jbcollier]

The gear selector uses a tapered pin.

The parts book and the service station manual are excellent.

scooterhelp.com/serial/vespa.parts.html

scooterhelp.com/serial/vespa.manuals.html

www.scooterhelp.com/serial/service.V5A1T.V5B3T.VMA2T.html

[stellp]

Nice one thanks for your help mate 👍🏻