Dual plugging

[John M]

Hi there , I have been wondering what sort of gas mileage improvement you might expect to see with dual plugging in addition to the other benefits it brings. My heads are off for a top end rebuild and it seemed like a good time to consider this option. Best Regards John

[Rob Valdez 79 R65]

Suecanada had her head work done by a fellow in Canada - Bruno?

He could answer the one question that always pops into my head when someone asks this about a R65 - is there enough material in the R65 head to make this practical?
It seems to me I remember reading somewhere that one of the airheads suffered from this malady.

If you do have it done, I would recommend having a airhead expert do it, and I think that is Bruno, and your parts wouldn't have to cross the border.

Yes - Bruno's: http://www.brunos.us/cylinderheads.html

[Barry]

I have been wondering what sort of gas mileage improvement you might expect to see with dual plugging

A wild unqualified guess 5 -10%

Haven't heard of R65's been dual plugged although there is some info in Tom Cutters manual so it must have been done. A search on the airheads list might turn up something. To get the maximum benefit from dual plugging you might need to raise the compression ratio at the same time especially if yours is a low compresion engine.

R100's would seem to benefit most as having a large 94mm cylinder bore the flame front has a long way to travel. Having said that an R65 bore at 82mm is the same size as an R75 so not exactly small.

Besides Tom Cutters and Snowbums articles on dual plugging there are a few others. Here's a very good one you may or may not have seen http://www.gunsmoke.com/motorcycling/r100gs/dual_plug/index.html

[Bob_Roller]

Can't really tell from your avatar, as to what year bike you have, but if the color is original, you have a '79 or '80 model year bike .

If you already have two ignition coils, any idea where you can mount two more coils ?

[John M]

Hi Bob, my bike is a 1986 monoshock

[Justin B.]

The '80 R65RS that is now in the possession of Suraklyn is dual plugged but we never got around to hooking up the bottom plugs as the PO had removed the ignition bits.  From some of the reading I've done I think the major improvement are more tolerant of fuel quality and maybe better starting.