The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: fbenach on February 16, 2012, 08:39:44 PM
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Hello everyone.... another question for the wizards!!!
A friend of mine is putting together a "cafe racer style" R65... the original bike is a R100 with its engine working properly...
Now, my friend doesnt want such a big engine on his bike, so we were wondering if we could exchange engines (I dont mind the upgrade), but are not sure if the R100 will fix in my bike and viceversa... anyone tried this? is there any kit/change/thing that has to be done in order to do so?
Will my transmission resist?
Thank you in advance!!!
Regards,
Fernando
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If he want's an R65 and you want an R100, Then, Sounds like you need to just swap bikes....
And, bike for bike, They're both going to have about the same amount of power.... It's not like the R100 is light years faster than the R65....
A little, Yes, but not as much as you'd think.. Swap bikes and go for a ride and let me know what you think...They'll both scare the piss out of you above 80 MPH... ;D
John
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Putting an R100 Engine on a lower R65 frame would give engine clearance problems especially during cornering.
I remember seeing an LS model being fitted with a R100 engine, although he retained the R65 gearbox. I forgot who made it, But I am pretty sure it's in the forum somewhere.
Just forget the engine swap thing, It's really just easier to swap the bikes themselves as the frames, gear ratios and a whole lot more are different.
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The frame geometries are the same, though some of the brackets and attachement points are different.
The engines will swap one to the other, and the transmissions will also swap, if they're from the same generation - pre or post 81.
But as has been said, it's probably best just to swap bikes. You'd also have to swap final drives if you swap engines. Then the speedometers would be off, but they won't interchange...
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There is only about 1/2" difference in ground clearance between an R65 and a R100.
I have both an R65 and a R100 - the length of the front forks is very similar, if not the same, when the bikes are at rest on their side stands. The R100 has a longer travel and was more softly sprung as standard than the R65.
The difference is accounted for in the front wheel size and the rear shock length. The R100 having a 19 inch front wheel instead of the R65 18 inch. That is it. This difference can be tuned out to some degree without major expense (spacer in the forks and shock preload) - if it is required at all. In the real world you might even be able to scrape an R100 head in an R100 chassis before you scrape a R100 head in an R65 chassis......
I will get my tape measure out tonight - if Justin does not beat me to it. And put up the differences in my bikes. However - many people have changed to progressive/firmer springs in their forks and uprated shocks, which will change things.
I feel that this is nothing to be concerned about on a road bike.
If you are cranked over enough to scrape your heads on an R100 then I would suggest you get off the road and onto the track before you kill yourself!
The real difference between an R100 and an R65 is the forks and yokes. The frames are very similar. The R100 has yokes with a smaller offset and the axle is mounted in front of the fork leg. The R65 has a yoke with a larger offset and the axle is mounted in the centre of the fork leg. This means that the R65 has a steeper steering geometry which makes it steer quicker than the more lazily raked R100. There might also be a difference in the swing arm length. this also gives a R65 a shorter wheel base.
Most larger airhead riders would never admit that the R65 has the better chassis than that found in the larger brothers. And they will come up with all sorts of bollocks to back up their theory. And the scraping of R80/100 heads in a R65 frame is one such example of internet myth. They do not understand that the R65 was developed with more sportier credentials that the larger touring bikes. They cannot get thier heads around the notion that the larger, more expensive, bike does not necessarily make the sportier bike.
Let your mate make his mind up and rejoice in you new found grunt if it goes your way.
For me I am happy with the R65 engine I have in my Cafe Racer. and am also happy with the touring R100. I can afford to have both bikes. But if there ever came a time when I had to down size to just one bike - then it would be a hybrid.......I.e. I would be putting the drive train of the R100 into my R65 chassis.
Rev. Light
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So in other words, Putting the R100 Engine and tranny into an R65 is a straight forward and modification free process which would create a bike with the sportier feel of the R65 with the improved power output of the R100 without sacrificing any mobility brought about by the 1/2'' lower ground clearance.
Sounds like the ultimate Airhead to me.
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It is.
Its been done many times before, and is certainly easier than trying to pry some more BHP from and R65 motor.
The biggest worry is the old pre/post 81 business, i.e. the type of flywheel. You do not need to swap the gearbox, as they are the same unit, if both bikes are from the same era. But you will need the final drive to match, along with the exhaust (which might have to be modified), carbs, etc.
I do know who will be getting the better deal out of this engine swap though.
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IF you do not swap the final drive unit and keep the R100 engine with the R65 final drive, the torque of the R100 will give you some faily impressive acceleration off the line, but the engine itself doesn't rev up as quickly, and your top speed will be limited as the R100 engine does have a lower "red line" than the R65. In most R100 bikes properly tuned up, the R100 will just pull to the redline in top gear, but that is ~ 20MPH more than the R65 top speed. With an R65 final drive, the R100 will run out of RPMs before it runs out of HP.
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The R100 cylinders stick out an inch farther, and with the ground clearance less on the R65 you could get into trouble on a tight bumpy corner. I've never sraped a valve cover, but know people who have.
When doing the swap, one thing as yet not mentioned is the exhaust. The muffler mounts are different, so custom hangars or exhaust would be in the program.
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the exhaust is a pain in the ass,
The rear mounts are only a direct bolt up for the odd shaped R65 mufflers.
Been there done that.
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The point I was trying to make earlier is that the R100, as standard, has softer, longer travel, suspension than the R65. It is after all a touring bike. The fork length of both bikes, at rest, is the same or very similar - at least my bikes are. The R100 forks have the ability to travel further from that start point than the R65's can?
This might mean that an R100 could deck its cylinders before an R65 fitted with an R100 engine when under load. So if someone was able to deck the cylinders on an R100, it does not necessarily follow that they will deck them sooner in an R65 chassis.
In the end you have to make you decision based on the roads you will be using the bike on and you riding style. In the UK our roads tend to be flatter - i.e. no excessive camber (although it is present, obviously) and they are not in unreasonable condition. And we have corners.
I measured some key aspects of my bikes last night and stand by my comments above:
1. At rest both sets of front forks are the same length. However I am aware that both bikes have heavy duty springs in them - i.e. neither are standard.
2. The rear shock on the R100 is half an inch longer that the rear shocks on the R65. Both bikes are equiped with Koni's. However this can vary when you start mucking around with the preload.
3. The standard front wheel on a R100 is an inch larger in diameter than the R65. This accounts for the 1/2 inch higher at the front of the R100.
4. The R100 swing arm is significantly longer than that on the R65. Which obviously makes the R100 longer wheel base when added to the difference with the forks. This make the R65 much livelier - which is my experience.
Some things are just a little bit more complicated, when you start looking into them. Whatever, there is no reason why you cannot easily and cheaply, give the R65 a little longers legs if you want to.
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Interesting data Steve. I'll have to measure the height to the valve covers or the ground clearance. That's not the same, is it?
I believe I weighed my LS and came up with 425 lbs. That could make a little difference in the comparison as well - at the very least, 50lbs lighter than the bigger beemers.
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Thank you all... I get the picture quite clear...
I was expecting more difference on horse power from one engine to the other.... if thats not the case, We will just put together the R100 away from my R65 and have fun driving both!!!
Thanks for the info, you guys are great!!
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You're welcome!
There is a difference in horsepower - but coupled with the lower final drive the R65 doesn't feel that much less. At least for solo riding. Loaded down touring, or with a passenger, you'll definitely notice the difference climbing mountain passes! Count on it!
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1. At rest both sets of front forks are the same length. However I am aware that both bikes have heavy duty springs in them - i.e. neither are standard.
I have to disagree, as the forks are an inch shorter on the twin shock R65 bikes, than say on a 79 R100.
At rest is not a good way to compare apples and oranges for these factors. same goes for the shocks.
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I will measure the same on my bikes - i.e. The height above the ground of my cylinder heads, in the upright position, with weight on wheels. I will use the centre nut as the point to measure to, for comparison. I have a 1979 R65 and 1982 R100. And I bet if you had an RS or RT fairing on they would sit lower.
Wirewrkr - I do not dispute the fact that the R100 has longer travel forks. We are discussing where they sit at rest - the point from where they start moving up and down.
But we are comparing apples and oranges - as neither of my bikes forks are standard internally - they both have heavy duty fork springs in them. And both bikes have koni's. I can't remember whether the front springs are progressively wound though, which might also make a difference in the ride height
There should be something like 20+bhp difference between the R100 and R65. This varies between models. I would be noticable - especially the torque. But on the road the R65 seems to be able to hold its own, especially when not weighed down.
However none of these issues should be insurmountable and it certainly would not stop me from going ahead with this excercise.
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DO ITTTTT!! To make everything easier, depending on the year, swap transmissions too. only problem i ran into putting a r90 motor in my 65 was the ignition. going from a wire harness for electronic ignition and trying to make it work for points was tough. this all again depends on the year of the motors though. exhaust was no problem though as i wasnt using stock bmw mufflers to begin with, if you're swapping, you'll need his mufflers to modify because your headers are smaller.
as for the final drive...leave it if youre putzing around town, it turns into a completely different animal. touring or commuting or if you just that concerned about mpg, change it. i left my stock 32/9 on and the first test drive after everything was squared away scared the @&!% outta me! no clutching or anything, just a handful of throttle and i stood my 65 up in the air almost falling off the back! now i don't wheelie on purpose but it wasnt the last time that happened. if i'm ever inclined to ride with gusto, 1st to second is a wheelie and 2nd to third is a wheelie...just saying.
the most valuable piece of advice i ever got was to WRAP YOUR FRAME! go get some blue painter's tape and make a good 4 or 5 layers on your frame lowers to protect the paint. that motor is small but awkward to take out even with someone helping and i promise that it will hit and/or be rested on the frame at one point or another. be careful not to hit the neutral switch and bend or damage the tabs.
also, it's common to remove or slide back the swingarm in order to pull the trans, then pull the engine. not unnecessary. it was easier for me to unhook the driveshaft, pull the rear motor mount, then tilt the motor and trans up towards the backbone of the frame, THEN pull the trans.
if i think of anything else i'll post or if you have questions, feel free to ask. i did the job on my own so it's not impossible or even drawn out, it just requires alot of patience. good luck.
SUPPORT HYBRIDS!!
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So I went home last night and sat on my 1982 R100 in the garage near a wall so I could keep the bike dead upright. My son measured the height from ground level to the left rocker cover centre nut.
15.5 inches.
The we did the same with my R65. 16 inches!
Yes, you read it right, the R65 was higher up than the R100. No one was more surpised than me, we had to repeat the excercise, just to make sure! I thought they would be close, but I did not expect my R65 to have more ground clearance than the R100. But as far as my bikes are concerned, that is the case.
The rear shocks on both bikes were set to the minimum preload. I suspect that the type of springs fitted to the front forks has a lot to do with this result. But I also suspect you will find with standard springs, both bikes might be more equal footing.
I also am aware that my R65 is a 1979, which means more weight. Heavy Flywheel, heavy bosch starter, heavy iron liners, etc. Putting a lighter R100 engine in the frame might make it sit even higher.
So like awaffa2003, get on with it! Great bike by the way!
Rev. Light
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awaffa - did you notice any ground clearance issues? Scraped valve covers?
I also prefer the method of removing the rear engine bolt and tilting the engine rather than removing the final drive. Used that method just this last weekend performing a clutch replacement.
Steve - glad you re-checked your measurements - I wouldn't have believed it either. Guess I'll have to measure mine now!
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you scrape pegs before your scrape your heads i'm sure. if not the pegs, then your feet. honestly if you're THAT worried about it, weld some plates on the valve covers. ACTUALLY i lied, get your friends R100 and your 65 side by side in the garage and lay them down on the heads. take a few steps back and ask yourself, "am I really going to be laying myself over that far" the answer will probably be no and if it isn't, i suggest that you invest in some knee pucks and stop talking to Reg Pridmore...
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True enough! I usually scrape a peg, side or center stand, or my foot first. The worst case is a bumpy corner that bottoms the suspension and loose a lot of ground clearance; a good reason to stiffen the suspension when riding sporty.
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yeps. it's not as big of an issue as people make it out to be. don't let a few degrees of lean angle dissuade you.
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For any street riding, I tend to agree - I've dragged my pegs, feet, stand, and mufflers on various airheads taking corners on the streets, but never valve covers (though some bumpy corners made it seem like a close call)
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Scraping things while cornering is a very subjective issue. It depends on how people ride, how they corner. I've followed riders that 'lean out' ie they push the bike down and keep their body more upright. Riders that 'countersteer' through every corner will also run out of clearance long before a rider who sets themselves up and 'leans in'.
Unless I have seen how they ride I don't put much weight on claims of 'I was cornering so fast I scraped my pegs'.
Leaning in will maximise ground clearance, the extreme example is motorcycle racers who of course don't have any choice if they want to corner as fast as they do.
Leaning in is also invaluable on wet or gravel roads.
I'm not casting aspersions on any posters here who have scraped bits of bikes, I have been caught out on bumpy corners under brakes, I'm just passing on theory learnt through many years of instructing motorcycle rider training classes.
Cheers
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I think what we need is a few more points of reference. Other peoples bikes might show other results, and we need to get an average.
Anyone who has both an R65/45 and a R60/R75/R80/R90/R100, to measure the ground clearance, as I did, as a comparison. All we need to know is the difference between the two, the bikes compared and any known modifications. If we can get even a small group of comparisons, that would be great.
Either way, I think we can agree that it would be cheap thing to sort if you felt you had an issue. And local riding conditions have a great bearing on this. Either by going for stiffer springs or even just a spacer in each fork leg to preload the ones you have. I am actually considering putting some spacers in my R100 to raise her up a bit.
And I have also seriously considered putting an R65 yoke setup on my R100 - but it is a complicated job, with instrument and ignition mount changes, not to mention changing the disc carriers and axle, as the fork legs are further apart. And I have to consider the rake and trail of the new setup - when using R100 stantions.
Personally, I would like to put this 'internet myth' to bed, once and for all, if we can. There is no telling how many people have been put off doing what awaffa2003 has done by attaching too much importance to fork leg length and not the real ride height of the bike with a rider on it. Its probably originally come from some armchair 'experts' at a certain other BMW site that I stopped visiting some years ago, due to some of the acrimonious arguments on there. Though I am led to believe it has quietened down these days and I still do occasionally lurk there as a guest. But they have always 'looked down thier noses' on the R65.
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And I totally agree with Bruce's comment about riding style as well.