R65 vs R80 vs R100
 

I'd like to have you BMW experts opinion on this: Is it better to go for the R65GS instead of the R80GS or the R100GS when it comes to longevity for the engine? The rationale goes like this: With less hp output (but with acceptable torque still) than the engine actually is capable of, and smaller pistons to move, the engine on the R65 will run with less vibration and perhaps be able to last longer than both the R80 and the R100? I'll be riding solo, occasionly with one of my kids riding pillion, no serious off-roading. Kind of like Iceland.

I was considering the R100, but stumbled over an R65 which was for sale for practically next to nothing. So - what do you think?

[This message has been edited by indu (edited 22 January 2006).]

I had an R65(but not the GS) for 12 years and had no trouble with it whatsoever.It was smoother and much more economical than the R8 0st i also had for a couple of years,although a little bit slower obviously(i'm not a slow rider but still managed to get over 70mpg).If you've found a cheap one and it feels right to ride,go for it!

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Just going for a short ride on my bike....

hello, the r100gs and r80gs are paralever, the r65gs and the r80g/s are monolever and lighter. monolever are supposed to be more reliable, see : http://www.micapeak.com/bmw/gs/

The R65G/S wasn't sold in north America, and I've never actually talked to anyone that had one. Based on the Mica Peak site, I have always figured it was a European market only bike identical to the R80G/S except for displacement. I suppose if the price is right it might be a good buy. I owned an R65 (non G/S) for a few years and found it underpowered for two up or loaded-with-luggage hwy speeds. As an around town bike, or for gravel roads I doubt this would ever be a problem.


As to the issue of reliability, I think the overall condition of the bike now (as a used bike 20 odd years old) will be a far greater factor then it being a smaller engine. In some cases, a smaller engine gets worked harder, as in run at a consistently higher RPM, so it could actually reduce longevity. however, I don't really think that is worth thinking about one way or the other.

I would assess the bike on it's merits of price and condition relative to what you are going to be using it for. It would be easy enough to swap in an R80 or larger motor at a later date if you decided you wanted more power.

I agree with Timo. The 2-valve flat twin isn't good for high revs, esp. when still cold. If the proposed R65 is in a good condition - why not. I prefer the R80GS, because it runs smoother than the R100 and is much easier on consumption. Additionally I had the pistons & conrods balanced. Now the engine runs nice & smooth. And hopingly 200.000 k's ....

Thank you all.
Thing is we're probably going for a R65GS for my wife and a R80GS for me - both in very good condition, both recently serviced and to very good prices. I think they'll be great for our use. See you on the road somewhere!

STRONGLY recommend same power for both - or you take the slower bike - or she leads!

See the threads on the "which bike" forum, especially this one for why.

There is virtually no difference in the R65 and R80 G/S's in weight or physical dimensions, only power. You could just buy a complete R80/R100 top end for the R65 if the bike is a great deal. I BELIEVE the entire crankcase / crank is identical - rods are shorter, and the rest outwards is different, but "top"ends complete are completely swappable. DO check to be sure first!

Grant

The crank is different on R65 G/S and R80/R100 (shorter stroke).

Rats - had a feeling it MIGHT be.

Oh well - can always swap the entire motor out! THAT's easy and very doable. http://www.horizonsunlimited.com/ubb/smile.gif

Right. Point taken, Grant - I'll take the slow bike then.

AliBaba: It's the R80GS which belongs to Mr. Larsen, whom I believe you know.

hi Indu,

Here are my toughts and advices regarding the 2 valves GS range.

I have an GS100 from 91,paralever, with fixed dash. Its a very very reliable bike, and torky, with wich I have covered over 140.000 k of travelling abroad. Still all original engine, gearbox etc oil consumption is lesser than 0,2 L/1000 km .

Lets consider some important basic off raods tech data of the GS65/GS80/GS80Paralever/GS100Paralever/GS100ParisDakarParalever


dry weight: 180/170/185/185/200 kg
HP: 48/50/50/60/60
torque: (I dont have fig.for 65) 61/61/76/76 NM at 3500rpm .
susp. travel front: 200/200/225/225/225 mm
susp. travel back: 170/170/180/180/180 mm
The paralever bikes has 17" rims in back instead of 18", front all has 21".
tankcapacity: 19/19,5/26/26/35 L
nr. produced: 1727/21864/14765/19701/11914

Out of this I would conclude first that there is no weight advantage for the GS65, only the GS100PD is heavier.
Also, the paralever bikes have much better susp. travel (offroad) and they have Marzocchi fork (225 mm). Tanks are larger on para-bikes too.
Last but not least finding a "good" GS65 is much more diff job than a paralever as lesser then 2000 GS65 were produced, compared to 45.000+ paralever bikes.

So dont hesitated, go for the paralever bike. You will have much more choise (from 2500 to 3500 Euro), bikes will be younger, and ofroads capacity is much better to me. I can follow (with luggages) easely enduro bikes on real bad gravel roads. Only on xtrem offraod and in the dunes the GS100 struggles, and is showing her weight.

I would prefer the GS100, 25 % more torque, same weight, but consumption can be a positive point for the 80.

My average mileage with a loaded GS100 is 7,5L/100 km on gravel .

Another choise (for a leigthweight or lady) is the F650 Funduro, which is not expensive at all (2000 to 3000 E) , much younger and over 35.000 produced.


I have bought 4 yr ago a second hand 96 for my wife with only 14.000 km. It has a lowered saddle height an is very reliable. She has about the same off road capabilities with a person of 50 kg as the GS range loaded. The only neg point is the cooling fan blowing hot air right on the legs ... (Should I say it keeps my wife ... ? )
With this bike my wife is as quick on paved and gravel roads, as I am on the GS100, with the luggages.

The F650 has a dry weight of 170 kg, susp. travel front/back 170/165 mm and HP is 48/57 Nm torque. Avg. consumpt is 5,5L/100 km with 17,5 L tank . It has about same travel capacity (w/o reserve) as the GS100 which is around 300 km.

I recommend to change the secondary transmission sprockets from 16/47 to 16/49 to get a lower first gear ratio as the monocylinder is a bit low on torque on low revs. No real change in motorway speed, (avg. 135 km/h)

To me the F650 is a much better buy for long distance travelling than the GS650 would be.

But ou can always choose for the monocylinder GS650 from 99 onwards. Its even better than the F650.

My wife does not want any other bike to travel W Africa.

Good luck.

Norbert

I am driving bikes since 1963 and BMW since 1974.



and with 60 BHP , which is more than enough, very handy.
Only problem is consumption, when loaded (bike + me 95 kg + 70 kg of luggage) the bike can go for up to 8L/100km on dirt.
Its not a fast bike on motorways, will recommend max 140 km/hr on odometer which is really 125/130.

I made a little mistake:

tankcapacity for GS80para/GS100paralever is 24 L istead of 26 L

There have been a limited number of these R65GS sold so consider it a collectors item.
Buy it and keep it in good order, change nothing.

The R65 GS produced 50hp, the same as the R80 GS. The shorter stroke added the extra horses for the smaller capacity motor but the downside is low torque. You will find the 65GS a happy rever and it is especially good around 5500rpm where it seems to almost get a sudden power surge. This again the characteristic of a short stroke engine.
I would say it is fantastic for one rider using it at higher revs and not loaded to heavy on trips but fun to play around with.

Are there two setups on the R65? The one we've been looking at had 27 hp?

http://www.bmw.mc.no/bmw/r65gs.gif

Type four-stroke, two-cylinder, horizontally-opposed "Boxer" engine, air-cooled
Bore/stroke 82 x 61,5 mm
Cubic capacity 649,6 cm3
Max power 27 PS (20kW) at 5500 rpm
Max torque 43 Nm at 3500 rpm
Compression ratio 8,4 : 1
Valves per cylinder 2
Valve control ohv, using push rod and rocker arm
Carburation system 2 constant depression carburettors Bing V 64/32/317 - 318
Engine lubrication wet sump
Power transmission
Clutch dry single plate, with lever-action diaphragm spring
Number of gears 5
Gear selection dog-type gearbox (ratchet foot lever)
Gear ratios 4,4 / 2,86 / 2,07 / 1,67 / 1,50 :1
Rear wheel ratio 1 : 3,44
Bevel/crown wheel 9 : 31 teeth
Electrical system
Alternator Bosch 280 W
Ignition Contact-free electronic ignition (Bosch)
Starter Bosch 0,7 kW
Spark plugs W 7 DC / Beru 14 - 7 DU / Champion N 9 YC
Suspension
Type of frame double-loop tubular frame with bolt-on rear section
Front suspension telescopic fork with hydraulic shock absorber
Rear suspension BMW Monolever - swinging arm
Spring travel 200 / 170 mm
Rims front 1,85 x 21 WM
Rims rear 2,50 x 18 WM
Tyres front 3,00 - 21 48 R
Tyres rear 4,00 - 18 64 R
Brakes front single disc brake Ø 260 mm
Brakes rear Simplex drum brake Ø 200 mm
Dimensions and weights
Length x width x height 2230 x 820 x 1150 mm
Wheel base 1465 mm
Ground clearance 218 mm
Tank capacity 19,5 l
Unladen weight, full tank 198 kg
Max permissible weight 398 kg
Fuel consumption 5,0 l / 100 km (at constant 90 km/h)
Acceleration 0 - 100 km/h 9,4 s
Top speed 146 km/h

27hp = the restricted version for sale to learners on restricted licenses. It could be easily de-restricted by the dealer when the time came.

Hi everybody,
I am from Italy (and new comer to this forum) and since 2004 I am riding a R100GS (1991): it is a funny bike, I can really go GS (in and outside the pavemented road)...

But... there is one aspect against...

Why this bike vibrates so much!? Vibrations are particularly irritating at the hands, when driving at 130/140 km/h and over...
This unpleasant "detail" makes the bike not comfortable at all for long trips.
Perhaps the vibrations of my bike are exceptional for some reasons I do not know.

Is anybody willing to give me some advice on how to reduce such a problem?

Many thanks, Superciuk

Yours may be worse than normal - or normal - hard to say - find someone who is an expert on the bike and get their opinion. Carb adjustment is the number one cause of excessive vibes - but they DO vibrate. The R80 is MUCH smoother.

This should possibly a new topic, but the horizontally apposed engine is naturally balanced and is one of the smoothest engine designs.
It is very important though that the weight of the conrods and pistons should be the same.
The conrods is more involved as far as their balancing is concerned as a large part of the conrod weight(bigend) rotate with the crankshaft, called the rotating mass, and a smaller part of weight(smallend) is moving back and forth with the piston, the recipocating mass.
To balance the conrods they should not only have the same weight but they have to have the same weight distributed between the bigend and small end sides.
To balance the Pistons and conrods is a very inexpensive and qiuck job. It get's done by removing material of the heavier items in a area where it does not effect the strenght or working of the engine.
The biggest job is to remove these items from the motor which is easier done than on any other engine.
The only reason why an opposed motor vibrates is because the pistons are not directly opposite each other.
The smoothes bike I have ever ridden is a old R80GS with the HPN 1040cc Malhe convertion
At 100km/h you could not feel any vibration through the handelbar or footpegs.(no cloves)

Take a look at my website, you'll find loads of pictures and also differences between the 2 R65GS and an R80G/S. I have an unrestricted one from the danish army, and there is a dutch merchant who sells unrestricted french versions (now and near future he gets more). Here is a picture of mine taken yesterday
.
http://westerbaen.tweakdsl.nl/R65GS/200/IMGP2572e.jpg

www.forcemotorcycles.com Have some ex-Danish army R65GS's for sale on their web site. If you have a use for one they look like ideal examples.

First you have to find the source/cause of the problem.

Tyres 'cupped'?

Tyres out of ballance?

Steering head bearings loose?
Swing arm bearings loose?

Drive shaft bearings going?

Valves correctly adjusted - remeber end float

Carbs ballanced correctly and not leaking?

Then you can think about engine ballance being teh source.. assumeing the road is flat of course.

If I were you i would do some carb maintenance. Change the needles and needle jets for new ones, and install a pair of new diaphragms. Then adjust carbs. finall road test the bike at your preferred cruising speed. If it vibrates, adjust -ONE- of teh carbs throttle cable a little bit, say 1/6th of a turn. does not matter which way. then re test the bike. If the vibration is worse, adjust it the other way. If better repeat the adjustment until it is worse, then reverse that adjustment until it is as good as it gets. The throttles only open a butterfly valve. carburettor opening is done by the diaphragms so they need to be similar. if the cylinders produce different amounts of power, there will be vibration. This advice assumes you have a good pair of plugs and the tappets are adjusted the same on both sides. Sometimes (not often)a coil with favour one side