R100gs with coverted motor from R80gs

[topher]

Hi, I'm looking for some advice about the above and would be grateful to hear a few opinions. My basic situation is that I am looking for a r100gs to undertake an overland trip later this year (Germany to Nepal and back). A friend of mine here in Bavaria (an engineer at BMW in Munich) is a GS enthusiast and is into restoring GS's - he currently has 5 which he intends to keep (he finds it almost impossible to let one go when he has restored it - much to the annoyance of his girlfriend!). However, he has one (a 1992 r100gs), which is currently in bits, that he would be prepared to put together and sell to me for a very reasonable price. The advantages of this situation for me are clear: I would be able to "help" him put it together and at the same time get to know the machine and gain experience which could be invaluable during my trip. Secondly, he has a vast array of spare parts and the machine would be essentially "custom" built for my trip (where appropriate). The only thing that concerns me is that the motor (which has done about 40000km) was originally from an r80gs and has been converted to 1000cc (I assume 980cc). Is this potentially a problem? (in terms of reliability, longevity, performance, availability of spare parts............). Like I say, I would be pleased to receive any advice/tips etc. relating to the above and also to general modifications that might be sensible for such a trip (a larger tank - probably the 43l from Touratech seems sensible but I am open to any other suggestions).

Thanks in advance!

Topher

 

[nud1e]

The R80GS engine upgraded to 1000cc is considered to be better that the R100GS engine - more torque and better fuel consumption. The upgrade is by cylinders and pistons. The bottom end is the same, as is the cylinder head and carbs.
Of more concern would be the paralever drive shaft which should by rebuilt by Eric Demant - if it hasn't already been.
43l of fuel makes for a very heavy bike and some reports suggest that the standard tank is more than adequate. A couple of 5l petrol containers might be a cheaper option for extending your range.

 

[JohnnyBoxer]

My 1000cc (80GS) was pretty nimble and I know Wreford, the new owner thinks the same

 

[(RIP) pastyman]

Ive got a TT 43ltr tank on my 100 and I have been very surprised how light it feels on the road. The weight is carried very low and although I accept that if it is dropped it would be heavy to pick up, but so is a heavily laden standard bike with a couple of extra tanks strapped on. The 35ltr PD tank is also a good compromise

 

[Garry H]

The R80GS engine upgraded to 1000cc is considered to be better that the R100GS engine - more torque and better fuel consumption.

I have both a R100GS and a R80GS...
The 100 is standard the 80 has a Siebenrock 1000cc kit fitted.....
The standard R100GS engine is better than the Siebenrock 1000cc kitted 80 .....
I find the standard 100 better on fuel and smoother at higher reves...it also feels like it's got more midrange power...
As for reliability they have both been fine ( i have done over 20k on the moded 80 ) without problems

One thing that is well worth thinking about is the standard 100 is 8.5:1 compression ratio and will run on poor quality fuel ....
The Siebenrock 1000cc kit is 9.5:1 and will not unless you reduce the compression ( then you lose power )

I think reliability would be fine with either...
BUT
Given the choice out of the 2 engines i would pick the stanard 100 engine every time

 

[Duncan Richmond]

Hi Topher,

I spent 5 years in India with my 80GS (for work reasons) I have the large tank fitted, but to be honest you don't really need it though it can be useful. I then moved to the Middle East for 3 years and fitted the sibenrock kit, it has not given me any trouble and the extra grunt is useful - it does rev out in top gear though so you have to watch the rev counter. Given the sort of trip you will be doing you won't be on a motorway much. The quality of fuel in Syria where I was based was hit and miss but didn't seem to cause any running problems with the Sibenrock conversion, I eventually rode the bike back to the UK with no problems. As Nud1e suggests get the shaft sorted as this can be a real weak point. Also a decent shock absorber. I would think twice about taking camping gear to use in India /Nepal, we never had any problems finding somewhere to stay (sleeping bag reccomended though) and it saves you lugging all that extra weight around. At the end of the day any reliable bike can do this trip so you don't have to go mad with the modifications, I have a German friend who has ridden a standard Enfield Bullet back to Germany from India twice without any major issues.
Best wishes

Duncan

Duncan

 

[topher]

Thanks for each of the responses to my enquiry! I'll think it over for a while, and continue researching, before finally deciding what to do. I've already spoken to Erich Demant (a very friendly and helpful chap) - he's sending me more information about his modification to the drive shaft.

Cheers

Topher

 

[Namastebuzz]

A person would need to be a total blithering idiot, with luddite tendencies, to ignore the perfectly sorted 1150GS in his garage and waste a good deal of time, thought and money on a clapped out dinosaur because he has some romantic notion about being "at one" with his machine on the road to Kathmandu.


Discuss...........

 

[Rob Farmer]

A person would need to be a total blithering idiot, with luddite tendencies, to ignore the perfectly sorted 1150GS in his garage and waste a good deal of time, thought and money on a clapped out dinosaur because he has some romantic notion about being "at one" with his machine on the road to Kathmandu.


Discuss...........

Whaat!!! outrageous behavior. You sir are banned from these hallowed halls until the time that you can see the error of your ways. A hundred lines as well if you will - 'I must not upset the dribblies'

 

[BamBam]

A person would need to be a total blithering idiot, with luddite tendencies, to ignore the perfectly sorted 1150GS in his garage and waste a good deal of time, thought and money on a clapped out dinosaur because he has some romantic notion about being "at one" with his machine on the road to Kathmandu.


Discuss...........

So The blithering idiots on the side of the road waiting for a BMW technician with a diagnostic computer would be the 1150 the 1200 and the hp2 owners. Not the Good old Airheads owners how can fix their bikes weaving wool and bobbins

 

[Namastebuzz]

I would have been disappointed to have any less vehement replies.

Well done gentlemen.



Actually THIS blithering idiot made the same trip on his 8 year old 1100GS without recourse to anything more than a feeler gauge, a plug spanner and a few allen keys. No factory technicians in sight.

Try getting up to 5600m without fuel injection!

Anyway....I'll get me coat before the ban kicks in.