Twin spark model 1150GS

[Rugged Path]

Slowly, slowly, I am seeing used parts come on the market on either ebay or from salvage yards for the twin plug bikes.

I have the single spark model 1150GS Adv. and was wondering whether the expense of buying (when available) used engine / electrical parts to do the conversion is worthwhile.

It is a bike I want to keep .

What is the conventional wisdom of the assembled , is it worth the effort?

 

[JohnnyBoxer]

Not worth the expense and trouble

 

[GS TRV]

Not worth the expense and trouble

+ 1 for sure

 

[MikeP]

First question has to be why do you want or need to twin-spark your bike?

As far as I know, the twin-spark was done to clean-up the emissions by ensuring all fuel was burnt.

Some people argue that surging is cured by twin-spark but there is also a lot of evidence that surging is cured by correct valve adjustment/matching of the valve opening in their pairs (something that BMW doesn't allow enough workshop time to accomplish in their schedules).

My own experience bears this out. I own a twin-spark and my mate has a single-spark that was surging when he bought it. Doing a valve adjust and taking the time to do it properly, has transformed his bike. It's smoother than my twin-spark now!

I reckon that twin-sparking will need some loom changes. The coils for single-spark models are used for the secondary plugs on twin-spark models and the coil-in-plug cap primary leads will have to tee into the HT circuit.

 

[Bronco Billy]

Yep what Mike says ......

I also own a Twinspark and before that I had the single spark. No difference mate. The best thing you can do is set the bike up as best you can with valve clearances, rocker shaft end float and throttle balance ....

 

[Eng]

TWINSPARK

Agree with the above! I currently have a twin spark, but have owned many single sparks and there is NO difference!

Cheers
Eng

 

[Paul Young]

I've been toying with this for a while now, too.

- I picked up a pair of twinspark c/heads for £20 over a year ago (just 'cos they were cheap, in excellent nick & I'd probably find a way to use them). Trouble was that they're off a different model & need the sweeping exhaust headers, like those on an 1100GS.
- I then got hold of another pair of coils & the rat-tail that will allow me to wire them in sequence with the ones already one the bike. My thought was that I'd fire both plugs simultaneously like on the twin-plugged airheads, rather than the staggered firing that BWM have arranged for emmissions reduction (the primaries fire before TDC & the secondaries fire at TDC)
- I've recently picked up a set of exhaust headers & a connecting pipe so, technically, I've got everything to make the swap... (Ebay is your friend )

Just a small matter of the c/heads not having cams fitted, so I was going to ask the collective... which cams should I go for? I could just swap over the ones on the GS, but I wondered if others were a little more "lively"...

 

[Twotter]

Just a small matter of the c/heads not having cams fitted, so I was going to ask the collective... which cams should I go for? I could just swap over the ones on the GS, but I wondered if others were a little more "lively"...

Don't Wunderlich do some hotter cams ???

 

[Paul Young]

Don't Wunderlich do some hotter cams ???

I think there are a few companies selling cam kits, but they're b****y expensive &, you may have noticed but, I generally try to pick up parts cheaply. What I was wondering was what other models with the same engine design have livelier cams - 1100S or 1100/1150RS?