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I'm rebuilding a 750GT that I picked up in December. It's got a 2nd plug in each head, on the opposite side from the original plug. The man who sold me the bike wasn't the one who had the 2nd plug installed, and couldn't tell me anything about it. Can anyone tell me anything about twin plug conversions, just to satisfy my curiosity?

Thanks - Peter Tourin

this is an old racer trick some folks did in the 70s - more spark, faster combustion. Won;t really gain you anything for normal riding but it does look pretty cool

That's more or less the way I see it -- I can't imagine that it'll do anything that I'll notice -- as long as it doesn't make things WORSE <bg>....

As Steve says, faster combustion, so you can retard your ignition somewhat. I've taken them back about 8 degrees.

TONY.

Gives new meaning to the old saying "I need it like I need another hole in my head"

why then did ducati race bikes have twin plug heads

Wasn't it to try to gain a complete fuel burn and like Steve said faster combustion, add to that larger carbs and flowed head ,,,,,,presto more power

Dual plugs were used on singles back when. On a hemi head they are great as the piston crown on a bike tends to obscure the flame front,masking the fuel.
This became real big in the late 70's on BMWs when octane was reduced.You can retard them significantly and hence run a lower grade of fuel.

Syd Tunstall did a lot of singles back in the 70's. I don't know if he did trwins but I don't see any reason why not. He had a lot of special tooling for both and did a lot of engine development in those days.