LCGB Forums

New engine build for a recent returnee to scootering .

I have made a boob and ordered a PHBL24 instead of a PHBL25. I don’t suppose it will make too much difference on performance (this is not intended to be a high performance engine) but it does mean that I am short of data as most information out there is for the 25mm carb, not the 24mm.

Has anyone got any data on the 24mm carb jetting, or suggestions?

Out of interest what inlet manifold are you using on the Casa 185 to fit the PHBL?

It appears many aftermarket ones won't fit without milling the gasket face on the cylinder (including the fin closest to the inlet). I know the Jet200/Casa Lambretta USA ones fit the clamp-on PHBLs,. My preferred type is the flanged type. I see Casa have recently released an X12 manifold specifically for the 185 but this is for PHBH type carbs. Depending on the hole spacing it maybe possible to swap the rubber for a Keihin PE20-24/PHBL/Mikuni TM24 one. Welcome any suggestions based on your experience.

I have purchased a Casa inlet manifold with the flange rubber. It was £60 from Andy Francis. I haven’t built the engine yet, but the new manifold looks fit for purpose and the notes indicate that it will allow a 24/25mm carb to sit in the right place to allow use of the original air box.

https://www.andyfrancisscooters.co.uk/casa-lambretta--new-inlet-manifold-with-bolt-on-rubber-manifiod-4395-p.asp

The flange rubber certainly mates with the PHBL carb ok.

I've seen a couple of Casa dealers listing these incorrectly as for PHBHs not PHBLs, so appreciate the clarification. Great to know the ID of the flange rubber is 30mm. It means it will also fit the TM24.

A bit more feedback.

The Casa manifold + PHBL fit well, but they are not compatible with the head cowling with the supplementary air intake. The float bowl catches on the ‘scoop’.

I have just had to remove the ‘scoop’ from the head cowling I am using. The alternative is to use or buy a cowling without such a scoop.