The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: mfrias2nd on June 18, 2012, 11:36:38 AM
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Hello Everyone!
I usually ride my bike around town and in the surrounding hills but yesterday was the first time I've taken it on the freeway with a buddy. At around 5k rpm's I was doing between 65-70. I felt that I was pushing the bike but was definitely in the slow lane. With that said it's an 82' with about 35k miles on it. My questions are...
Is 5k rpm's at around 65mph normal? or was I pushing the bike too much? (I heard it tops at around 100, I'm sure this is needle in the red though)
Can anything be done to increase top speed without modifying the engine? (IE gears, transmission swap etc.)
How does my experience compare to yours? Maybe my bike is lacking what is normal.
Your notes are always appreciated.
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Can anything be done to increase top speed without modifying the engine?
There's a little grippy bit on the right hand handlebar, twist it towards you to go. Red line's not until 6900 RPMs! 8-)
Sounds like to me you were not in top gear, probably in 4th gear. 65 mph @ 5k seems slow for top gear.
Disclaimer: my speedometer hasn't worked in almost a decade. American units where applicable.
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HAHA Right, and I do and when I twist back I fly but I can't do that for the entire trip which was about an hour.
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These engines are designed to spin, and are happy at 5K all day long, assuming that you are running it at a road speed that gives it plenty of wind to keep cool.
Just because some people think it looks like a tractor, doesn't mean that it is one!
5K RPM should be around 71-74 MPH, depending on your final drive ratio.
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Highway speeds will result in high engine rpm's with an R65 .
Your observations with your bike, are quite normal .
Other than spending a fair amount of money on different transmission gears, or a different ratio on the final drive, you're pretty much need to live with what you have .
If you change the final drive, you will change the 'character' of the bike and may not like the end result when you're finished .
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SOUNDS GREAT!
Thanks for the input.
My brother (who was riding with me) said I was screaming. Since I had never taken the bike on the freeway it was new to me and I do have louder mufflers so it was a bit of a mental thing hearing a screaming engine between my legs.
thanks again!
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Snowbum has a section on rpm/mph
http://bmwmotorcycletech.info/ringgears.htm
All you need to know is your drive ratio.
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Want to go faster? Dump your passenger. Well, not literally, but the R65 is a 650cc bike with a tractor-like engine. Lighter is faster. I do not carry a pillion rider on my R65s. Too crowded and when we're cranking through the twisties, their screams tend to annoy me.
I won't ask you about you and your brother's ATGATT total load weight, but that also make a big difference.
Both my R65s -a 1981 and a 1983- will easily hit 100 mph but it is necessary to use the gears and run the engine up in each of the top three gears.
If you need to go much faster with a passenger or a load of luggage, a larger BMW is out there waiting for you. Multiple bikes for different conditions is a good thing.
One up. Lighten up. Wind it up and Go. [smiley=clap.gif]
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Oh he wasn't riding with me he was on his own bike. I was solo...
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An airhead will run all day long at any speed it's capable of. The limiting factor is how long the rider can hang on for. Even an R45 is faster than I want to go for any length of time.
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An airhead will run all day long at any speed it's capable of. The limiting factor is how long the rider can hang on for. Even an R45 is faster than I want to go for any length of time.
best answer so far
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My 1986 r65 with its original 3.36 rear end would be at 4000 rpm at 100km per hr (62mph) I installed the Kaiser taller fifth gear this winter and now 100 km per hr is 3750 rpm . The bike pulls this gear easily and cruising at 130 kph feels more relaxed (4875 rpm )
John Muir
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What Barry said. I've read (owner's manual, I think) that the red line on the tach is the maximum sustainable cruising speed. It comes to about 105 and mine will just about do that, even with a Windjammer. When I rode to Medford down I5 a few years ago I kept it on about 6 grand most of the way, when I could see clearly no cops ahead. The motor felt really smooth at those rpms. When I hit some curves marked "45" they took me by surprise. They weren't kididng!
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My LS had the 32/9 3.56 rear end. At 70 mph the rpm where somewhere around 5600-5700.
A good friend offered his 37/11 3.36 rear end that he had around his shop for me to try. It is way better now with a little longer legs.
Rpms dropped t 5200 at 70 engine pulls without a problem. I could probably go a little lower to the 32/10 3.20 rear end, but i am having way too much fun to mess with it again so soon. The speedometer is off slower by 4 MPH than actual, but I just compensate and round off to +5 Mph for actual speed. All I had to do was swap the longer LS brake pads to the 37/11 rear, a new gasket, new oil on drive shaft and rear end, replace rear tire and adjust brake.
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Coming home from work today 65 mph was 4500 rpm's
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My 3.36 rear end coupled with the 6% taller 5th gear gives me an effective 3.19 when in 5th gear without affecting the lower gears.
Very sweet on the highway, I was a little concerned that the taller fifth would be to much gear for the bike to pull but it is a great improvement
when travelling at speed for a longer run. I don't do any long haul rides with a passenger.
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Hi John M: Your Kaiser solution sounds great. I may have to do a little transmission work soon. Where can you purchase the Kaiser 5th gear?
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Many years ago when the bike and I were both much younger I wound it out a few times to 180 kmh, it needed a bit of downhill assistance from memory.
The tacho needle is definately into the red at that speed.
Last week I rode the 200 km from Hobart to Launceston on a cold, damp and dark night. It really seems to like those conditions sitting comfortably at 120 kmh with a couple of short sharp sprints up to 140 and even 150 kmh just to break the boredom.
Tassy has some of the best motorcycling roads in Australia but unfortunately the Midlands Highway is not one of them.
They will run all day at whatever speed you choose to ride and they love to rev (in their gentlemanly, pushrody sort of way).
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I've heard the 3.20 final drive is a good match for these bikes, but haven't tried it myself. My LS came with the 3.56 drive and I've changed to the 3.36 and like it much better.
With quieter mufflers highway speeds might be more enjoyable. ;)
Oh, and fill out your profile so we can see where you're coming from!
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My R-65 will run 70-80 MPH all day long..
But it scares the crap out of me !
It takes a long time to stop that bike from 70 MPH... :o
Remember: They were made when 55 MPH was the speed limit everywhere...
John
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Hi doublezero
I had my transmission out to be checked and the circlip installed on the output shaft ( my bike was one of the circlip-less years )I decided that it was a good time to install the taller fifth, Sean Weaver of Black River Motor works opened up the transmission for me (I believe he ordered the gear directly from Germany )
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My 1986 r65 with its original 3.36 rear end would be at 4000 rpm at 100km per hr (62mph) I installed the Kaiser taller fifth gear this winter and now 100 km per hr is 3750 rpm . The bike pulls this gear easily and cruising at 130 kph feels more relaxed (4875 rpm )
John Muir
For those of us that travel relatively long distances on our R65's, can you tell us more about the "Kaiser taller fifth gear" you had installed? Haven't done a Google search yet...
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They're about $150 for the gear and drop RPM about 500. It's like having a sixth gear (but missing fifth).
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The clincher with changing the transmission 5th gear is that one is usually looking at at least $400 to crack the gearbox, replace the gear and and re-shim, and reassemble. IF anything else needs to, plus shipping, etc - it adds up pretty quick unless one is experienced in gearbox work and has the proper custom tools (which include a modified rear gearbox cover plate for the shimming bit..
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A 'new' final drive is way cheaper with a whole lot less downtime. But then there's the matching speedo...