Here we go again! Kickstart piston with pictures!

[sunrisemac]

just go on Photobucket and set up a free account, it's all set up for photo sharing in numerous formats including the img format required by most forum sites. You just click your uploaded photo and the different format options appear, click on the IMG option and it says 'copied', then just paste it into the post. It really is that easy

It really is as easy as coaster says using Photobucket

[alanscottj]

Couldn't do it from my tablet so managed to do it here on home computer







What I am being told from some shops and someone on here is that the compression is high and the pistons are not up to the job, apparently it is a common problem with the Mugello. Aramando's reckon they have some new pistons on order that are made of tougher stuff that those that I have tried.

[DigDug]

As Chris said I'd be happy to use any of those in one of my engines.

It's unlikely that you have gear cluster out of position so my money is on the kickstart lever / chaincase cover.

How thick is your gasket?

[alanscottj]

As Chris said I'd be happy to use any of those in one of my engines.

It's unlikely that you have gear cluster out of position so my money is on the kickstart lever / chaincase cover.

How thick is your gasket?

No idea how thick it is, I have always just bought standard gaskets, will have a look tonight.

You mention the kickstart lever, how could this be affecting things?

[bristolmod]

I think DigDug possibly meant the internal Kick start mechanism- these are a weak point on all Lambrettas and generally snap or fracture internally.

It COULD be that the internal lever is bent and not showing any signs (yet) of stress or fracture. That would mean that the operating mechanism (i.e. the K/S piston) was not completely parallel with the gear it engages with. Which in turn means that it will "fail" earlier than it should - hence 4 "failed" pistons so far.

Possible but I can't say for sure- all I can say is that those 4 pistons aren't too bad.

Chris

[alanscottj]

I think DigDug possibly meant the internal Kick start mechanism- these are a weak point on all Lambrettas and generally snap or fracture internally.

It COULD be that the internal lever is bent and not showing any signs (yet) of stress or fracture. That would mean that the operating mechanism (i.e. the K/S piston) was not completely parallel with the gear it engages with. Which in turn means that it will "fail" earlier than it should - hence 4 "failed" pistons so far.

Possible but I can't say for sure- all I can say is that those 4 pistons aren't too bad.

Chris

Thanks Bristolmod, I get it now. I am going to try one more piston (the new one from Armando's) and see how that goes, if it does wear down like this again I will try replacing the kickstart shaft (again!). I am going to invite one of the lads from the club who has been doing this stuff 30 years to have a look before I do anything

[bristolmod]

check out the bronze bush in the crankcase cover as well- if thats worn (and they do wear) that may cause the shaft to "tip" slightly in operation thus causing the piston teeth to miss the gear.

Let us know how you get on please.

Chris

[coaster]

Is it possible that you have an early style shaft in a newer (GP) side casing? Innocenti strengthened the shaft for the introduction of the GP (DL) and the boss that the shaft turns in is approx. 2mm shorter to accommodate the uprated shaft which is 2mm longer. A short shaft in a GP (or modified Li) side case will struggle to be long enough to fully engage. It's a long shot but someone might have some measurements?

colin

[alanscottj]

Is it possible that you have an early style shaft in a newer (GP) side casing? Innocenti strengthened the shaft for the introduction of the GP (DL) and the boss that the shaft turns in is approx. 2mm shorter to accommodate the uprated shaft which is 2mm longer. A short shaft in a GP (or modified Li) side case will struggle to be long enough to fully engage. It's a long shot but someone might have some measurements?

colin

Could be Coaster???

Also, I replaced the original side casing with a polished one last year. The original kickstart shaft broke and when I replaced that I put on the new casing, I am tempted to put the original side casing on to see if that could be the problem.

[coaster]

Is it possible that you have an early style shaft in a newer (GP) side casing? Innocenti strengthened the shaft for the introduction of the GP (DL) and the boss that the shaft turns in is approx. 2mm shorter to accommodate the uprated shaft which is 2mm longer. A short shaft in a GP (or modified Li) side case will struggle to be long enough to fully engage. It's a long shot but someone might have some measurements?

colin

Could be Coaster???

Also, I replaced the original side casing with a polished one last year. The original kickstart shaft broke and when I replaced that I put on the new casing, I am tempted to put the original side casing on to see if that could be the problem.

I worked at a Lambretta dealers in Ipswich in 1970 when I left school and remember that the only replacement shafts supplied by Innocenti were the GP type. There was an official Lambretta service Agent tool which was used in a Pillar Drill to remove the required 2mm from the boss on the inside of the casing for older models.