Top chain guide damage

[Northener]

Found bits of metal when changing gear oil & sought to investigate, found my top chain guide to be damaged (on a bog standard GP150), it was originally set as per factory at 12mm play, it was after I set to 6mm play that the front of it had the chain cut into it about 10mm.

Any ideas on what caused this?

I then reset to 12mm after changing the guide - obviously, on taking sidecasing off again there is once again but this time very slight wear as though cutting in again.

I have now replaced both guides with NOS Innocenti ones, set at 12mm play.

[Tractorman]

Did you turn the engine over and check the play in several places? One of the sprockets may not be true so the chain is tightening in one place.

[HxPaul]

Did you use the standard GP chain (Indian Rolon)because they're renown for shedding rollers and they could catch on your top chain guide.

[Northener]

Thanks for replies, it's Italian & has Regina chain (although will double check at weekend). When I first got it I looked it over & set the play to 6mm as modern thinking although it was set at 12mm - it's all very much as it was when it checked the factory.

I assumed me setting it to 6mm was the original problem but I see some slight wear into metal again after resetting to 12mm.

Would you believe one of the sprockets to be 'warped' Tractorman or even clutch needs aligning??

[Warkton Tornado No.1]

There's certain things that I do as a matter of course, regardless of the state of tune, & besides never, ever allowing Rolon chain anywhere near a Lambretta, I would never use the standard chain tensioners again.

They really are not up to the job.

I must have dozens of standard tensioners that will never get used, but I keep them, along with all the air filter boxes with their restrictive hoses, for when they become 'collectible'..........

[Mrnice71]

There's certain things that I do as a matter of course, regardless of the state of tune, & besides never, ever allowing Rolon chain anywhere near a Lambretta, I would never use the standard chain tensioners again.

They really are not up to the job.

I must have dozens of standard tensioners that will never get used, but I keep them, along with all the air filter boxes with their restrictive hoses, for when they become 'collectible'..........

l agree never use standard tensioners , get yourself an MB one , some engine builders even leave the bottom tensioner out