Originally Posted by
guyhockley
One of my first jobs as an apprentice was helping to twin plug a couple of cylinder heads. Not for performance, though, it was a VW 1200 for a plane!
My father decided to take up flying in his mid 60's. At one of his first post flight social cuppa's he had to explain to a group of tutors exactly why you did a mag drop pre flight...They'd always done it because they were taught to.
Wonder if the second plug is something to do with emissions? Adding a third one is probably just psychological - people like symmetry. Think Aprilia used the same basic engine with a 5 valve head - that could do with all the plugs you could squeese in?
Saw an interesting french supermono that took a bit of head scratching. Rotax motor, air-cooled cylinder, water-cooled head but it had the intake cam lifted and very down-draught inlet. No idea if he changed valve angles. Bike also had an airbox feed through the headstock, first time I'd seen that.
Bookmarks