R80 or R100 ?

I'm looking for opinions... I've got a 1986 R80 that is a great bike. I love the handling, it is extremely smooth, and I like the looks. It is extremely comfortable for me to ride, but I'm weary of doing more than 70 on the highway because of the gearing. I'm pretty light, so I don't need more power, but I definitely wouldn't mind an extra 10 horses.

I've found a 1982 R100 nearby that is also a great bike. My question is... is it worth selling the R80 and buying the 1000cc? I've got no problems handling the R80 around town, will an R100 feel that much different? Will I miss the monolever suspension?


Thanks for any opinions... this problem is definitely a good problem to have, because either way I'll be riding a great bike.

The 750's, and 800's, are the smoothest running of the twins, but a R100 is going to have more torque and will pull a taller gear. If you pack double with gear a R100 is probbaly a better choice. If you ride solo, put a higher gear ratio, lower numericaly, final drive on your bike. It would be cheeper than another motorcycle.

Ken G.

The monolevers have quite a few advantedges over dual-arm bikes: low maintenance wheel bearings, no rear drive splines, tubeless tires, better brakes...

Install a set of 1000cc cylinders, and if you really want fewer revs,, install a taller RDU or ring and pinion. If you balance the rods and new pistons, it'll be every bit as smooth as a stock R80.

From what I can look up quickly, your 1986 R80 should have an 11/37 rear end in it. To drop your RPMs at speed, you can drop in a rear end from a similar errar R100RT or RS which should have an 11/33. That will give you a bit more comfort at cruising speed, but your acceleration from a stop will be slower than you have now. If you are not of the hard fast acceleration crowd, you will never notice it. Plus, it should also give you a higher top speed. Bolting it in is very straight forward.

You will have to change your speedometer as well to match the rear end. Probably get one from the same bike the rear end comes from.

You can easily check which rear end you have as it is stamped into the top of the differential near the breather.

I don't think that your top speed would increase with a taller final drive - the R80 doesn't produce enough horsepower to still pull redline with a much taller rear drive, unless you're going downhill, I think. You would get more relaxed cruising, but may need to sometimes downshift for a pass whereas before you might not have needed to downshift.

Still the R80 is a smoother machine than the R100. I like the monolever bikes, though the engine tuning on them generally emphasized lower end torque over peak horspepower, compared to the earlier bikes. If you are thinking of adding a sidecar, you're better off with the dual shock/2-sided swingarm frame with the tapered wheel bearings for handling the side-loading. If riding without a hack, the monolevers are pretty nicely setup. The R100 has a noticeable/useful increase in "grunt".

Keep the R80 - don't sell

I would keep the R80. You know what you got.

Then again I am bias... I got an R 80, put an RS fairing on it... changed the rear end to drop another 500 rpm on the interstate... Mine loves to run between 80 and 90 mph, smooth. I will never sell it, only add to it.

Thanks for the responses. I'm leaning towards keeping the R80, as it really is a nice bike. I have all the maintenance records for it, and it has been taken care of for its entire life.

I'm not so concerned about top speed, as 90mph is plenty fast, I just am not comfortable revving my engine at 5 grand for an entire tank of fuel.

Any long trips I take on this bike will be solo. I have an relative willing to lend me his K100 for any two-up trips, and that K is truly superior in every way for 2-up riding.

Thanks again,

Kirby

Don't worry....

If you tend to your maintenance, your bike should be able to run at % grand for, oh... Maybe the next 20 years!

I woke up this morning and keeping my bike just feels right. I'm a college student and live 3 hours away, so I'm going to head home tonight, drop my car off and pick up the R80, hopefully making it back to class tomorrow morning.

Keep the R80. Enoy it. They are probably the smoothest of all boxer engines.

And yes, if you do change the rear gearing you will drop the revs and will get a higher road speed out of it. We did it to my Brother-in-law's 1978 R80. He also wanted to drop his revs. Dropped in a set of gears from a broken R100RT (32/11). Dropped engine speed significantly. Dropped hard acceleration a bit. Got to a higher indicated speed, just took a little longer than my R100. Now he is much more comfortable on long trips.

My 86 R80RT has 32/10 stamped on the housing. It is geared very well for the engine. Besides the rear suspension, the R80 has the improved valves for lead free gas. If the R100 has not been upgraded, that is another expense you will have in the future.

I brought the R80 up to school with me, so I'm going to be keeping it. Riding it for 4 hours, it'll cover 80% of my highway needs.

I didn't remember to look at what ratio is stamped on the housing, but the bike starts getting ready to play at 70mph. It feels great, I'll just have to get used to the rev's.

You have to remember that our bikes like to rev and running below 3000 rpm does not do the engine any justice. They like to run around 4500 rpm.

Keep the R80!

shire2000 said:

Keep the R80. Enoy it. They are probably the smoothest of all boxer engines.

And yes, if you do change the rear gearing you will drop the revs and will get a higher road speed out of it. We did it to my Brother-in-law's 1978 R80. He also wanted to drop his revs. Dropped in a set of gears from a broken R100RT (32/11). Dropped engine speed significantly. Dropped hard acceleration a bit. Got to a higher indicated speed, just took a little longer than my R100. Now he is much more comfortable on long trips.

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Dave,

My first two RS bikes (a '77, then a '78) each had 32/11 final drives.

My current ('77) RS has a 33/11 final drive when I bought him.

Personally, I like the 33/11 MUCH better, even on the 1000cc bike.

Much peppier around town and pleasant on the highway as well.

I think it would make a better ratio on the R80 (vs the 32/11.)

The R80 is smooooooooooth! A keeper, for sure!

Orbitangel, your info tab says you're from Oshkosh. Small world, I go to school in Appleton. I don't see many airheads in Chicago, but I see even less up here.

Orbitangel,
Back in the day, yes I am starting to sound like an old fogey , we used to swap out rear ends on a regular basis. Trying to get that perfect sweet spot. Most of the RT crowd kept with the 32/11 as it was a good touring setup and worked fine around town as long as you kept the revs up a bit. The RS crowd liked the 33/11 as it gave them a bit more punch at low speeds and still gave good "Sport Touring" capability. At the other end of the spectrum was the 'Cafe Racer" crowd who liked 37/11 which gave great acceleration at the cost of top speed. And of course the sidecar crowd tried just about anything they could get their hands on to get the optimum setup. Don't really remember what most settled with, but I think it was around the 32/10 setup.

In Europe the 32/11 was called the Autobahn gearing, which gave the highest top speed at the time, and the 37/11 was called the Alpine gearing. Autobahn cruising was and still is pretty high speed. The Alpine gearing was used more for climbing thru the mountains and the fun twisties.

All in all, which gear setup you use depends on what kind of riding you want to do. All of the "stock" ratios are fine for all stock bikes to be able to cruise at 80MPH all day long. Some will be revving a little higher than others, but none of them will be over revving at normal highway speeds.

At least that is what I remember from "Back in the day".

Small World

Kirbster919 said:

Orbitangel, your info tab says you're from Oshkosh. Small world, I go to school in Appleton. I don't see many airheads in Chicago, but I see even less up here.

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Kirbster,

Yeah, Oshkosh - very close to Apple Town!

I just agreed to do a little Airhead work for a friend, on his newly acquired R80/7, dressed-up to look like a silver smoke R90S.



The thing had been sitting for quite some time.

I installed all new fuel lines, set the valve lash (there WAS no lash), timing was way off (firing at TDC), new battery, new air filter, oil and filter change, not much more (YET.)

Took her for a spin yesterday. She runs like a scalded dog (37/11 final drive) and is sooooooo much smoother than my R100RS.

Still, very capable of keeping up with highway traffic, light, easy handling and fun to ride.

This one has some serious cosmetic issues (rust, mostly) but I would LOVE to keep it!