Originally Posted by Macca
Just doing the sums and there's about a AUD $5000 (US $2500) difference between the R80GS and R100GS, so if I was to purchase the R80GS and put the spare cash (who's got spare cash these days?) into 'jazzing' up the bike mechanically (Munich Motorcycles - and this is not intended to be a commercial plug) am I on the right tangent, or go for the R100GS.
The bike is for two-up travel, and I note that Grant does recommend either the 80 or 100 for two-up (I actually prefer the Tiger but that's another storey).
Also guys & gals what would be the preferred options to the 'winner'?
Macca & Lynda
Without adventure life is in full decay.
It depends more on your requirement than on the differences between these two beemer options.
R80 runns ok/well with a road-weight(?) of 350-400kg. 450kg is ok as well, but hitting 500kg... it does get sluggish...
It is a smooth running, sweat and soft engine, especially in the version that you are asking about (8.2:1 50hp).
You will however find that raising the compression by swapping pistons to the 9.2:1 55hp pistons will be a -good- investment. The engine becomes a little "raw" though, and a triffle "nervous".
R100 - far more power. Better milage. Runns cooler. Raw. Brutal. Not to my liking (though I do use them).
The light-weight tune-up kit from Germany is however a very neat tuning; the engine will not be as brutal and raw. It will be more rev-willing.
In either case, both models benefits from oil-cooler...
As for cutting costs...
50hp... vs 67(ish)hp
50(ish)Nm... vs 75(ish)Nm...
...that -is- a huge difference...
You will/may spend a bit on fixing the power-less 800cc engine I guess...
55hp and 56Nm is ok though... and that will set you back about 3-400USD (if prices have not risen since I checked), if you can swap the pistons yourself i.e.
As for tuning options:
The 800 cc engine benefits hugely from T-shaped high-flow valves, e.g. Buggpack 44mm. That would require new seats though, so less you plane to change seats 42mm high-flow-valves would be your option. Bugpack valves costs about 50-60USD each, needs to be shortened and new collet groves swiveld and lasp-caps added. The power increase is modest, but pushing the power just over the sluggish limit; the engine will get that little extra that makes it ok to drive.
Dual-plugging is a tuning that I recommed, but it is costly. (I wrote about it in 2008; "ITU gone bust" I think I called the string).