R65 LS Vs R65 Mono.

[Motu]

Went up to a mates place tonight to help with his Commando,and thought I'd better take his LS for a ride before he sells it.It has a 2 into 1,and Heidenau tyres,so I should feel at home.

What a little bike it is! It feels much lower and shorter than the mono,I don't like narrow bars,and hated these same bars on the mono,but it seems a perfect set up with the LS.The bike was very nimble and changed lines quickly considering the narrow bars...it feels like it leans over more than the mono,but a check of cyl head clearance in corners shows it maybe doesn't lean over as much as the mono...and the side stand scrapes.My mono is not standard,if you have seen photos of it you'll it has been set up a bit strange....suits me.

I expected differences in the chassis,but what interests me is the differences in the engines - how does a 50hp engine with max torque at 6,500 rpm compare to a 48hp engine with max torque at 3,500 rpm? I have heard that the R65 engine has a vibration,my mono hasn't,the LS sure has,it's almost like a Triumph 650 in comparison.The LS is a revvy little engine,on paper they make max hp at the same rpm,but the LS is red lined higher...makes me feel a little easier about over revving the mono.Although the mono is happy to rev out to max,the LS just loves to live there - I can keep it up around 6,000rpm in the twisties,on the mono I would upshift.The mono is much stronger out of corners with better torque down low,but the LS goes a gear down and just rips.The mono is geared higher,and that half a gear down helps the LS.

The LS rides like a 250,it needs to be thrashed,the Mono is a short shifter,it grunts along like a bigger capacity bike - and I think that's what BMW had in mind when they made the R65 Mono,so it wouldn't seem like a small engine in a big bike.I can cover ground faster on the Mono because of the short shifting - it's very much like the Yamaha XS1 I had,I never revved that bike,just rode on the bottom end.The Mono also works better in gravel - I come out of a corner at 3,500rpm and apply throttle,it slides and then hooks up,the LS needs too many revs and hasn't got that bottom end grunt to give the power band I need.

We came back,and then I rode the 850 Commando...it has carb problems,fitting the new Tri spark ign didn't help.It's hasn't got 250cc's more grunt than the R65 - I'm still really happy with the mono...but I'd like an LS in the shed too.

[Barry]

Very interesting comparison Motu.  I always liked the sound of peak torque down at 3500 rpm on the mono engine for loss of only 2 hp.  I wonder what they actually did to re-tune the engine and if it could be done to the earlier versions?  Maybe different valve sizes or cam timing  or perhaps inlet/ exhaust tuning and the lower compression.

[Motu]

So which is the faster bike? Too many discrepancies on the net,especially regarding the Mono.But basically they weigh practically the same,and top speed is within 1 kph.Zero to 100kph,the LS is nearly as fast as the R80,the R65 Mono a lot slower,by nearly a second.The slowness of the Mono would be largely because of the higher gearing - by the time it got up and going,the LS would be long gone.

On a race track the LS would pull away from the Mono,the lower gearing and rising torque curve making it a faster bike on the track.On the twisty back roads we ride in NZ,the Mono,especially mine,would be the faster bike.The Mono has so much more stonk out of corners,and the 4,000rpm wide powerband means it can be held in gears longer - the LS would have to be unmercifully thrashed to keep up...but having fun doing it.

Here are the HP and torque charts - HP and torque on the LS are perfect sloping lines,what you would expect from an engine like this.The Mono has a torque curve that's almost flat,with a strange dip at 4,500rpm,and the HP curve has lumps and bumps.What I wonder is how BMW did this.
R65 LS





R65 Mono

[Rob Valdez 79 R65]

So which is the faster bike?

It is irrelevant to me, as anything over the speed limit seems to get me in trouble with the coppers and the insurance companies.

[Motu]

On our back roads 120kph is about as fast as you can go....and there are no Cops out there anyway.

I hope...

On my test ride I never got into 5th,and pushed it to 70mph on the speedo.Actually I put it into 5th to check rpm at 100kph/60mph.

[trolle]

Maybe different valve sizes or cam timingor perhaps inlet/ exhaust tuning and the lower compression.  

The carburettors are definitely different. I tried riding with mono carbs on my '84 which meant a higher consumption without any discernable improvements in power. The carbs have a heavier return spring for the diaphragm piston.

greetings from a grey north

[darrylri]

On our back roads 120kph is about as fast as you can go....and there are no Cops out there anyway.

I beg to differ with you, Motu.  When I visited your lovely islands, I rented an R80GS Basic.  I believe that bike is good for just slightly over the ton.  My friends were riding an F650GS and an R1100RT (two up), and I was chasing them the entire two weeks.  I wore a hole in my glove from holding the throttle to the stop.  But it's true that we never saw any cops.  

[Semper Gumby]

Egad!  Wrong side of the road.  Gives me the willies!  

Good pictures though.

Do you have AMALS on the commando?

[Motu]

I go on backer back roads than that!

The 850 has a single Mikuni,and was jetted wrong.The pitfalls of buying a bike that's been sitting for 4 years and no history.You'd expect it to be jetted correctly if it was a conversion...or we did anyway.

[darrylri]

The next time I get back to En Zed, I'm going to let you guide me around!

[Motu]

Anytime - but if you ride with me you might have to step into some gravel.