I have an old (25 years +) t1600 briggs & stratton twin. Starts fine but after a minute starts to splutter and l.h. plug oils up + if filter off spray is pressured back from float chamber. Assume carb ok or both plugs would be affected. No sump pressure problem. Wondered if faulty inlet valve was allowing pressure to back feed, but with heads off no visible problem.

Any ideas (inc. how I could get at side valve to check further/ where engine number might be found etc/ where an old manual could be got

Alan Tunbridge Wells, April 2009

Assumng you have changed the plug, the likely answer is a faulty coil. Replace it with a new solid-state version, cut the wire to the points, and connect the stop wire to the tag on the new coil. The coil is not the cheapest (I'm assuming it's he flat twin wth the double-headed coil) but it's better than scrapping the entire machine!

phil_saunders(a)bigfoot.com

Phil Saunders, April 2009