Bristol Mod Scooter Club

that piston has "caught" some time in the past- i.e. its seized. There is also evidence of "blueing" on the gudgeon pin indicating overheating.

From memory I think you had a 175 conversion done on that engine so you will need an oversize 175 conversion piston- not a TV175 piston as the gudgeon pin heights are different. Scooter Restorations do these pistons I think, and also good small end bearings.

Steve at Piston Broke knows his stuff- simply give him the cylinder and the new piston and he will bore to suit (3 thou clearance). It might be worth asking him to put 2 small holes on the exhaust side of the piston to aid cooling- hes done a few for me and it certainly helps.

Beware, Steve can talk for England.

Yes - it is a 175 conversion and it did 'nip up' a couple of times when running it in!

Would Steve at PB not be able to supply the piston as well?

don't think so- he has a limited stock of "Lambretta" pistons. Your best bet is Scooter Restos.

http://www.scooterrestorations.com/lamb ... ome-rings/

dependant of course on the size you need.

Jim,

Just picked up one of those....

http://www.scooterrestorations.com/lamb ... ome-rings/

and got Steve at Piston Broke to rebore the cylinder.

I needed a 62.2 piston but couldn't find a decent quality one anywhere so went up to 62.4.

I left the cylinder with him and it was done the next day (£30) - he offered to do it while I waited but I had to get on.
You need to write off an hour at least when you take it in - he talks more than Clive.

Thanx for the tip mate!

Was browsing the Scooterotica forum and there is a posting from a guy with symptoms remarkably similar to yours Jim, including a video of the motor running. Similar suggestions regarding small end, big end, piston etc, but also one posting suggested it could be the chain or tensioner making the noise. Just a thought, no idea how to test this apart from chaincase off and have a look, or using a stethoscope !!
Unsolved mysteries are interesting, but can become very frustrating after a while. Bizarrely this guy's noise started after he changed the carb. ?????????????

Just to add the posting was in the Scooterotica 'Lambretta Tech' section and was titled 'Rattle!!!'

Yep - thanx Nick! That is a similar noise to mine! I'm going to crack open the crank case and have a look! I remember back in the day when the chain guide on my TV 175 series 2 snapped and a chunk of it got wedged in the gear box! I was popping along at a fair speed, and needless to say the engine instantly locked up and that was the longest rear wheel skid I have ever done!

Last week I took a cylinder and head to Piston Broke for rebore and head re profile. What a guy that Steve is! Knows his stuff and I now see what you mean Chris and Nick (GI) - had a really good chinwag about engines and just about everything else as well!

These sort of blokes are priceless and we need to keep 'em in business! Highly recommend him!