Dual Plug Systems and other Questions

[110066]

I have been talking with a guy about buying his '79r100rs and I thought I pop a few questions into this forum about this bike

Dual Plugs
One of the "features" is that this bike is dual plugged with a ignition booster system what are the pro/cons of this arrangement? Was this an option from the factory? will a bmw shop work on bike with upgrades like this on it? I know my (gasp!) Honda NT650 had a dual plug system - but it came that way from the factory.

Shift Kit
It also had a "shift kit" installed - what are these? and again are
there any down sides? he said it shifted really smoothly

any kind of help would be great

thanks

[srb]

Dual plugging was not a factory thing back in the 70's, and I don't think BMW ever dual-plugged any airhead from the factory. Someone with more technical knowledge can answer the pro/cons. I wouldn't let the dual-plugging be a deal breaker, I know plenty of people that have it, and don't have any problems. As far as dealer work, I have difficulty getting to do anything to an airhead. I use an independent shop. If I were you I would call the closest dealer and ask them straight up, or go there and see if they have any airheads in the service area. Usually a service manager will be happy to let you talk to their airhead expert. I am not quite sure what the shift kit is, I do know that in 1978 BMW added linkage to the shift mechanism to make it easier to shift. That may be all it is. If the RS fairing is in good shape, that alone could make this a good deal as those fairings are becoming a little more scarce. Good Luck!!

steve
'79 R100S

[lkchris]

Along about '83 BMW improved the shifting of this transmission.

Older versions can be modified by installing some new parts, commonly called a "shift kit."

Done well with the actual BMW parts, this is a good thing.

[WesPeterson]

Originally posted by brian thompson
Dual Plugs
One of the "features" is that this bike is dual plugged with a ignition booster system what are the pro/cons of this arrangement?

thanks

this link will give you some info about dual-plugging

http://pub217.ezboard.com/fairheadte...picID=17.topic

[DrCurve]

Oh Man, is there ever a lot more to it than that. Tom's book, as he says right up front, was OK at the time for him and some others................but don't go there now. Lots of information on dual plugging out there. Lots of things not said in his early papers on this subject. A number of us were "on up the line" by that time however. Very interesting subject over the years...........and now even more so with the new GS and its "phase shift" which I wrote about in On several months ago. Dual plugs on airheads is the way to go........just make sure you get it right. Best,

[110066]

Thanks for all the input on dual plugs
I finally made made a decision and decided to go with a 4 plugger - It just happens to be a K

Thanks for all the help - I can tell that this Forum thing will come in handy!

[CustomSarge]

Shift kit: aftermarket(?) shifter drum with different curve guide patterns to move the shift forks that move the internal gears. Objective: smoother, quicker shifting & elimination of unintended neutrals, most notably between 2nd & 3rd. My 1st BMW, an R90/6, got one from Capital Cycle after I burnt up 3rd & 5th due to not knowing tranny oil is separate from engine. Since rebuild was in process, upgrade wasn't expensive. Change was SO good I nearly swapped trannys for it when I got the R90S & sold the /6. I don't think I'd rip a good tranny just for that, but if it's down anyway, I'd do it without doubt.