Q: R65LS - rubber engine mounts?

[65shawn]

Hi all,

I am the proud new owner of a r65LS and one of the first things I noticed was a discussion on the vibration at around 4k rpm. And then I noticed some talking about rubber aftermarket mounts that ... worked for the vibration ... but ... would also work at cracking the frame over time.  

So my question(s) :
How do I know if my mounts are rubber?

And if they are how afraid should I be of a compromised frame on my new prized bike?

I think the bike has in between 30 and 40k on it according to the previous service records (Speedo Changed by previous owner for a pretty looking one with only 11k on it).

Any advice or help is appreciated ...

[georgesgiralt]

HEllo !
If OEM, no rubber mount on the engine. As per the vibration, you can change the RPM at which they show by modifying a little the torque at which the engine mounts are torqued. And you can reduce them further by ensuring the valve lash is perfectly set and the carbs are properly tuned and clean. This last point will increase gas mileage too.

[Luca]

The rubber vibration dampers were for the front mount only.  If you have oem mounts, there will be a metal washer between the engine and the frame.  Also, the rubber dampers require that the front mount be double nutted (jam nutted) on each side, so that should be a good indicator of what's on your bike.

Plenty of people will tell you that the dampers are bad for the frame and don't address the cause of the vibration (poor tuning, wheel balance, etc.)  Others will say it's the only thing that kept the r65 ridable for them, and put many miles on them without any frame issues.  It's like asking what the best oil is for your boxer  

[montmil]

... It's like asking what the best oil is for your boxer  

Luca! Shame on you for trying to start another DOT.

BTW, What's the best oi... oh, never mind.

[65shawn]

Thanks for the replies, friends. Put some miles on it tonight will look at the mounts tomorrow AM when it's light.

I saw some forums with BMW mechanics talking about hi mile bikes with the rubber mounts having frame issues (either by user error or by incorrect mount design) and of course ... that's something that I take seriously.

Bike's tuned well, got it from a lifer that has had over 60 different personal Boxers go through his garage. Likes to rev high it seems like. Strange power distribution in the revs as well, different than I expected from a BMW.

But yeah, this bike for bay area riding is just fine for me. And the fact that it leaves a little drop of oil instead of a puddle (like all my Triumphs have) is a refreshing thing as well. I'm sure even that drop can be remedied. This bike makes me want to wear a white tuxedo to ride everywhere.

[Luca]

The short stroke means it does like to rev, but it should still have the traditional boxer torque curve (nearly flat).  Power should climb smoothly until redline. The throttle tube does not pull linearly on the cable, though.  You get more throttle per degree of rotation as you reach closer to WOT

Keep the revs up a bit for a longer lived battery and timing chain.

[Matt Chapter]

This bike makes me want to wear a white tuxedo to ride everywhere.

A couple of times through college I went without a 4 wheeler for one reason or another.. reminds me of the time I showed up to a friend's wedding in a suit on the beemer.  Classy!  Had to take it easy on the shifts to save the wing tips though.

[65shawn]

The short stroke means it does like to rev, but it should still have the traditional boxer torque curve (nearly flat).  Power should climb smoothly until redline. The throttle tube does not pull linearly on the cable, though.  You get more throttle per degree of rotation as you reach closer to WOT

Keep the revs up a bit for a longer lived battery and timing chain.

This makes a lot of sense.

The torque is pretty pronounced at 3-4k. Been riding almost every day around town, and night before last I noticed the thing really start to open up around 5-6k... and then I thought to myself: "well perhaps I haven't been letting it hang around 5-6k" I think also the carbs just needed to be run a bit, and now it's performing more evenly.

Does this bike like sitting around 5-6k rpm ?

From Wikipedia:
The power output of early R65 models was 33 kW (44 hp) but from 1981 this increased to 37 kW (50 hp) at 7,250 rpm Similarly in 1981 torque rose from 50 N·m (37 ft·lbf) at 5,500 rpm to 52.3 N·m (38.6 ft·lbf) at 6,500 rpm.[5] This propelled both variants from 0–100 km/h (0–62 mph) in 5.8 seconds. The R65 could do the standing 400 metres (quarter mile) in 14.3 seconds and the standing kilometre (0.6 mile) in 28.1 seconds.


I think I may just be feeling strange about letting it be in that rpm range due to my other bike being a 77' t140 750 bonneville and it's more of a low-end torque bike.

Was also told by the former owner who had over 60 beemers that I should't lug this bike so I have been trying to treat it more as a high revving thing, and mind my shifting to keep the revs high.

But for this bike: what is "high" exactly ?

[tvrla]

Don't make the engine 'work' below 3K. Lugging is where the engine feels like it's working hard - it'll vibrate and complain.

The suspension is kept in line by the frame, and the engine is a stressed part of the frame. The frame really needs the rigidity the engine provides. The bike will handle better without those rubber isolators and even though the frame might not crack in the next 20K, enough have had it happen to not risk it.

Vibration is minimal when the engine is properly tuned and running right.

[Barry]

I think I may just be feeling strange about letting it be in that rpm range due to my other bike being a 77' t140 750 bonneville and it's more of a low-end torque bike.  

I had a T140V back in 75. I'd be interested to hear your comparison between the R65 and T140V in terms of handling and performance.

It's a long time ago but my recollection is the T140V was gutsy low down but ultimately not that fast and the vibration levels tended to discourage high revs. Handling was very good though and it made a fabulous noise. I wish I still had it.

[Luca]

The torque is pretty pronounced at 3-4k. Been riding almost every day around town, and night before last I noticed the thing really start to open up around 5-6k... and then I thought to myself: "well perhaps I haven't been letting it hang around 5-6k" I think also the carbs just needed to be run a bit, and now it's performing more evenly.  

I don't hold it that high unless I'm in 4th (without a reason to shift up) or 5th.  Around town I tend to keep it at about 3500, that way I have no reservations about cracking the throttle open if I want or need to.

Less than 3k and you're not at full ignition advance, which is hard on the engine when you make it work at that range.  Also, the cam chain and sprocket are lubed by a straw coming from the oil pressure bypass, so at low revs there is much less lubrication to the timing gear because there is less excess oil pressure.  You also won't start charging your battery until somewhere around the mid-range

Another thing about lugging an air cooled engine:
air cooled engines rely more heavily than liquid cooled engines on the exhaust system for cooling the engine.  At lower rpm's you have less exhaust flow and thus the engine does not rid itself of heat as well;  especially when you are making it work.  To counteract this air cooled engines tend to be jetted rich on the idle circuit to keep things cool.

[Barry]

I never deliberately lug the engine but winter temperatures provide a dilema where you have to choose between lugging and reving the engine with cold oil. On my short commute low oil pressure is never an issue at any revs because the oil just doesn't get hot enough and cold oil is my real concern. I measured oil temperature of just under 50 Deg C  (120 F) when I got home the other night. I compromise and ride between 2500 - 3500 RPM with an occasional burst to 4000 and  I do what I can to reduce oil cooling by fitting my custom made valve covers when the temperature drops.  It's not enough though. I really could do with a sump heater.

[65shawn]

Good advice, all.

Barry, I don't have to worry about excessive cooling, I'm in Sunny Florida. I wish it would get excessively cold here and kill all the pythons and mosquitos.

Also at your request I gave some run downs of my limited experiences with other bikes in comparison with the r65.

In short over all the r65 wins. But the t140V was/ an amazing bike from model year 76-early78 for the pre emissions motors.

I did that review at the below link so as to adhere to the rules of the forums ! 8-)

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1384839135