Scooterotica

90% of the time they're a can of worms and what seems like a two hour job can take 2 days as unforseen issues and previous bodges appear that need sorting. Those mechanics that work from home generally charge around £20 per hour but I've heard of main dealers charging 4 times that amount as they've got much higher overheads to pay.

Harry barlow charges a flat £250 to tune and build a engine you pay for any bits he turns them around in about 2/3 weeks

Like most experienced Lambretta enthusiasts I can strip and fit piston barrel head exhaust and carb in about 2 hours give or take.

Here's where the time goes though.!!!!!!
Strip/refit rear runners and bridge piece. 10 mins - 60 mins.

Clean old gasket faces/flat cylinder head ......?

Check ring gap /head squish ....?

Strip refit engine cowlings ....?

Strip old exhaust and probably fettle new exhaust to fit....?

Fit new carb and then remove headset top so as to fit new throttle cable. .....?

Remove carb more than once to jet correctly .....?

Remove spark plug several times to check jetting .....?

Trust me; these are all the things that have to be done AND there will undoubtedly be other obstacles on the way. Yes it will be worth it in the long run but your costs are gonna come from what I always call the "non-sexy" parts of the job.
Day's work at whatever the hourly charge is.