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Collection, Preservation and Display of Old Lawn Mowers

Piston Rings 75cc Suffolk

Hello to you,

my name is Jan-Henrik age 46 - I am new to old lawn mowers and to this forum. The other day I bought my self a Suffolk Super Punch 17``in nice condition. And I fell in love with this engines. I bought 4 others since then - in very different conditions. Only one have realy strong compression and it´s the only one wich does not smoke - not even a bit.

Here comes my question: What is your experience - will new pistonrings bring up the compression, and stop it smoking?

 

cheers Jan

Forums

wristpin Fri, 22/11/2013

Maybe!

Worn rings will cause oil burning as will a worn bore, worn valve stems and guides and a sticky crankcase breather. 

Start with the breather behind the valve chest cover below the inlet and exhaust manifolds. Carefully dismantle and clean it and if the little "paxolin" valve disc has a worn face try turning it over to present an unworn face to its seat. It should be reassembled with a paper washer between the valve body and the cylinder block.

Any further work depends on the availability of new piston rings and it's possibly not worth spending further time on the engine unless you know that you can obtain these.

Central Spares are still showing pattern 75cc rings in both standard and +ten thou 75cc oversize but nothing for the 98cc as far as I can see.

Other than the very early machines I would expect to find a 98cc engine on a 17" machine and not a 75cc one.

PTR48 Sun, 24/11/2013

A likely cause of poor compression is a leaking exhaust valve due to burnt valve face and valve seat.

PTR48 Sun, 24/11/2013

A likely cause of poor compression is a leaking exhaust valve due to burnt valve face and valve seat.

jan-henrik Mon, 25/11/2013

OK - thank you! This is something to deal with. I havent got time the next 10days - so it ´ll take some time to get the engine running.

Jan