Greetings The above mower bought in 1981 is putting burnt oil smoke out of the exhaust box. Suggests needs new set of piston rings. Any one any experience of re ringing this engine and ideas of possible snags. Can I expect the bore to be standard size. Snags on fitting new rings and where to get them. Any suggestions greatly appreciated regards Bob
Petrol Mower Suffolk Punch Model 30 12" Engine Assy A98
Jun 22, 2009
2 Replies
Blimey. Blast from the past that one.
Not much help, is that the sidevalve 4 stroke?
Might be valve stems/guide wear as well...
Or even just a build-up of crap in the head which is stopping the valves from operating properly. The B+S engine in our mower has a surprisingly small service interval between pulling the head and de-crudding it (5 years I think, without checking - so if it's never been done it's probably long overdue on a 28 year old engine)
Pulling the head's probably a good idea anyway just to check for bore wear, damaged piston etc. (although I suspect the OP's likely done that already if they're the sort that's up for fitting new piston rings :-)
Heck, if it derives timing from the flywheel then it might even be a sheared flywheel key and the timing's just completely off.
cheers
Jules
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