I am currently plotting and planning to fit some wider wheels (well, on the rear, at least) to my K100RS. I've procured a set of wheels, one as-new, one second hand. I'm gunna have 'em painted gloss black in a coupla days, a week or so. I've got a nice set of radial Pirelli Angel ST tyres in 160/60ZR18 to fit the 4.5x18" 3 spoke rear wheel and a 110/80ZR18 to fit a rare as rocking horse poo 2.5x18" 3 spoke front wheel that came standard on later K75S models but were a little-used option on other models of the era. This is not a typical wheel/tyre combo as the bikes with an 18" rear wheel had a 17" front wheel, and mostly vice versa, except for drum rear brake K75 'plain Jane' models, if you think about it a mo'. I realise I'm treading (embrace the pun!) in some slightly new territory but this combo is not too far away from typical.

Today I had a chance to bolt up the rear wheel to see how it'd go on a non-Paralever rear end for which it was not intended by the factory. I was not surprised to see that the rear calliper would have to come off during wheel with tyre ingress and egress. The 140mm I've got now just fits the calliper to exhaust space that's there. I did not fit the tyre to the wheels for obvious labour-saving reasons. I was surprised to see that the 4.5x18" wheel slid right in with a whole heap of room on the swingarm side. It also clears the newer, narrower-looking K1100 centre stand I fit up a coupla weeks back. With the tyre mounted I see that I might have to use an additional 2mm spacer 'tween the final drive and wheel, but the current wheel bolts will be long enough. Here's a picture of the wheels as they are now.




In the end it'll be sorta like a K1100RS out back...and a wider wheel and tyre looks better to me, and we're hoping it handles better as well.


There are a few mm's more clearance from a 4.5" rear wheel (as compared to a 2.75" stock wheel) on the swingarm side and heaps of clearance on the exhaust side. There is probably some 'offset' built into this design. Slipping the tyre in there without the wheel shows it to haveenough clearance without an additional 2mm spacer, about like the stock wheel. The option of using that additional spacer is mine as I have an extra, but with my non-scientific look-see I don't reckon it's necessary.


And on the left.

The front wheel is far less drama as it simply accepts my recently upgraded 292mm Suzuki brake discs with 8mm aluminium spacers on each the side of hub, mated to four piston Brembo R1100GS callipers and the K1100RS 20mm master cylinder. It's close to stock size. Let the games begin.

Thanks for the detailed post TWB. It will be great to get your seat of the pants impressions when the conversion is up and running.

I for one, would be interested in how you went about your front brake upgrade and what you think of the results.

Thanks again...

Dee Why

Off course you appreciate the tyre is wider than the rim, so if the rim just about fits.......

Dee Why, I have done something similar before with a Y spoke wheel on an Airhead, the same front wheel and two piston brakes as an early K bike. I'd already had the discs, three of them, machined to accept the four 10mm bolts through the hub. The trick was getting them centred in the middle of the four piston callipers. For that I had a mate fab up two 8mm wide aluminium spacers to sit on the hub and properly align the discs to the new callipers. Here's a pic...you can see the aluminium contrasted against the black wheels. These 292mm diametre x 6.5mm wide discs came off some late '80/early '90s era Suzook, dunno which. They fit right up into the callipers with a whisker to spare to clear the calliper bolts that hold the callipers together. The 'feel' is far better, more powerful, progressive and solid. I went up to 10W fork oil to contain some of the increased dive since I was using only 5W for its supple feel over bumps. I also have the firmer, shorter travel K75S forks fitted.



The master cylinder came off a K1100RS and is the 20mm version since a 13mm stock version gives you no pressure at the lever to speak of. The switch gear attaches as original and the bonus is an adjustable-throw lever. I used Venhill braided stainless hydraulic lines through the fork stem as original too, and attached them to the lower steel lines, no need to use the banjo bolt design of the later models. Too easy!


The goods.


Bonus adjustable lever, but the throttle cable must be changed. It no longer uses a gear and chain, instead, a plastic guide tube and the cable rotates round the throttle tube's end, and the cable slips between the fuel tank and steering head instead of going down from the front inside between the steering head tubes, so it's a more direct route. I had to fiddle with the other end of the cable too since at the same time I fit K1100 throttle bodies. It was a half a day project, all up.


The goods getting bled. The pads I had in them were getting a bit thin (about half worn) so today I plopped in some new EBC-brand FA407HH sintered pads and can't wait to try their increased braking once they 'bed in' a bit. Basically, I have a larger footprint pad area over larger diametre discs, twice as many pistons (albeit of a smaller diametre), and more hydraulic pushing power. It works, but it's essentially the same as any K1100 model, so it's a subtle upgrade but worth it.

Rene, goes without saying, mate. I didn't come down with last night's rain. Though with my penchant for doing these mods as they come to me I'm like a kid in a lolly shop!

Good stuff!



Ehh, whilst living in Scotland, can we forget any references to rain?? We have enough as it is!

Our annual 'rain festival' will be upon us soon enough, though it will be nice and warm...

looking good mate ....

cheers !!!

Thanks for the detailed reply TWB. Much appreciated.
Your red RS is constantly evolving. Great stuff.

Cheers, Dee Why

The rear wheel and tyre should fit in OK, TWB.
The wheel I used had a Bridgestone radial on it and it fitted no problem once the caliper was unbolted to allow it in.
It looked really good from the back.
I have heard of one person who claimed it did touch the swing arm though. May be down to tyre choice if that turns out to be a problem. Don't forget BMW allow a tolerance of 5mm on the back wheel.
The rear was the easy part. I gave up the conversion when I realised the whole front end and brakes needed swapped over. That front wheel you picked up would have made things so much more straight forward. I believe the first 16v K100RS used the same front wheel. Again, very rare.
Be really curious to hear how it handles when you get it finished.

I recall your write-ups about using a wider wheel out back, Comber. I could see that the 17" front wheel and brake swap was gunna be a fair bit of hard yakka so I opted for the 'easiest' option. I'd already been in possession of the four piston callipers and discs for a few years with this in my mind's eye, but man, I had a search chasing that front wheel! I finally dragged one out of a dusty corner at Iron Horse motorcycles in sunny Tucson, Arizona after someone pointed me there based on an ad in a local BMW club newsletter, after they spotted my wanted ad on www.ibmwr.org ...long way round but it got the job done. I knew what I was looking for and when I started it would be like peering into the dark with my only source of light a flaming faggot (a lighted bundle of sticks tied together and used as a torch, for those not up on the origins of slang).

I've just added up my receipts and all up the two wheels, various international postage, two new Pirelli radials, K1100 centre and side stands, four additional wheel bolts, 2mm wheel spacer, front wheel bearings and lock ring for the 'as new' front wheel, 20mm master cylinder, throttle cable, Venhill brake lines, and new EBC pads have cost me just under AU$1000.

Money well spent? We shall soon see.

Two freshly booth sprayed and baked wheels with new Pirelli radial rubber spooned on and balanced, 5 grams each wheel. Tomorrow new front wheel bearings, brake discs mounted, then we roll.

sweet!!!!!



ima guessin that rear will get a few looks from the back ....from folks "in the know" .....looks awesome !!!!!

Tasty!!! Can't wait to see those on the bike.

OG

The tyre fits right in with plenty of clearance on both sides, much more on the swingarm side than the exhaust side, which surprised me. Only one 2mm spacer was used, the calliper must come off, and the exhaust rubber mount removed so the exhaust can be pushed slightly to the left away from the tyre, and it must be installed from underneath, so a bike lift with a drop-out was required. Alternatively, you and several mates could lean the bike waaaay over. Nuh! There are trade-offs! A fifth lug bolt without the cone goes in the centre to hold the adaptor for the centre cap. The K1100 centre stand is not necessary, in fact the left 'foot' rubs the left edge of the tyre, so it has to either be ground away or made to stand off a bit with a thicker rubber spacer. (See updated post below)


On the road the bike doesn't follow the contours and tar snakes any more and rolls easier into corners. In fact the front end felt very light, almost too light, not 'wooden' as when on bias ply tyres. I'll have to get used to that. I might have to raise or drop the fork tubes to bring back the feel of the former steady-on feeling, or I might just get used to it as is. The Pirellis are brand new so I went cautiously on roundabouts and corners and will do that until they 'bed' in a bit after fifty or a hundred kilometres. Oh, and the speedo reads about 2kms lower than the corresponding RPM. I used to go 100 kmh at 4000, now it's more like 97/98 kmh at the same RPM. I reckon the Karamba software is gunna get plugged back in to calibrate the speedo for the pessimistic error.


So far, so good.

thats a fair bit of work old mate !!

and an amazing "full of rubber" look from the back huh ?

and looks like the wheel diameter is actually smaller at the tyre outer or is that an optical illusion (whilst on the centre stand )

yeah i recon a couple of hundred will wash the slipery feel right away

good work...............cheers

Simply outstanding mate! Bike looks fantastic!! Thanks for all the details too. You cleared up a lot of misinformation and old wives tales.

OG

The bike overall has a nice "meaty" look to it.
Well done!

Red and meaty, like our bikes, Blakey!

I scratched the two day old paint on the back wheel in a coupla places fitting the calliper. Doh!

The rolling radius of the 160/60ZR18 tyre is larger than the 140/80VB17, so that's an optical illusion. Of course the sidewall is a 60 series so it only looks smaller. The back tyre took 5 grams to balance.


The front wheel balanced with 20 grams in the end, and the 110/80ZR18 has a smaller footprint and is smaller in circumference than the former 110/80-18 bias ply, which contributes to the 'quicker' feel in the 'bars. But, there's a 120/70ZR18 Pirelli Angel ST available...


The bike was really stable and planted, tracked true and felt really sweet in the twenty five-odd kilometres I rode from work to home and here and there. Tomorrow I will get a good run in before the rain falls again. For work I'm s'posed to attend the annual Laverda concours at Cleveland with our resto 1956 R50 & Steib sidecar. It's no longer held under the Storey Bridge in Brissy. Bathurst V8 Supercars is on the tele...hmmm, many choices. Let's see how I feel at seven AM...

oh! didnt know it was on .....i guess i wasnt back riding this time last year ..

havent been for a bayside ride far a while .....

http://www.webspawner.com/users/clublaverda/concours2011cle.html



thats a great looking pic twb .....

Sunday morning confession: I misspoke. The K1100 centre stand is necessary. Yesterday after fitting the wheel, but before I rode, I could see that the left hand 'foot' was making contact with the very edge of the tyre. I blocked it away with a sturdy rubber bumper and strapped it up tightly before riding home from work.

This morning after a good sleep I saw it was necessary to remove the entire stand and grind away only about a 10mm wide x 20mm length section of metal from the edge of the foot. This in no way compromises its integrity or stability on the ground. It now rests right up against the exhaust pipe rubber bumper as intended. Once the stand was on the ground I compared its spread against the K100 centre stand and the left leg of the original stand would contact the tyre directly. It can't be used, you must have a later model stand assemblage. Chalk it up to experience.

It's a beaut, sunny Sunday in SE Queensland so after doing the centre stand mods I went for a rippa ride on some of my favourite fast, curvy back roads round the neighbourhood, up the motorway for a stretch, then through the farmland towards Redland Bay to the motorbike concours, and am quite comfortable with the tyres now. The bike falls into the corners without having to be 'asked'. I'm getting accustomed to the very different feel. A fair bit of it was on gravel roads and she's lost none of that stability that you'd think with a wider tyre. I didn't whack the wheels onto a scale but in my hands the 3 spokes with radials felt lighter than the bias ply and 4 spokes, so the suspension is working easier as well. Me likey.

G'day TWB ,
a great contribution , I was sort of chasing the same goal with my bike but only managed to get half way there , I too was trying to go down the path of radial tyres , after looking for 2-3 years for the rare as rocking horse poo three spoke front I gave in and bought one new ( $1k ouch ! ) , my rear wheel is a 3 spoke 3x17 inch off a early 90's RT second hand for $200 , 1st set of tyres where Dunlop Roadsmart 110/80/18 front & a Dunlop D205 140/80/17 rear , they were quite good but Dunlop discontinued the D205 so when the time came to get new tyres the next option was an Avon Azaro ST on the rear which is just about the only radial that I know of in a 140/80/17 size with a Avon Storm Ultra 2 on the front in 110/80/18 size , results are not too good , all stability is gone , feel is quite vague , never mind , let me get to the point finally of my post , I think I will go down the path that you have outlined beautifully but a question , you mention a 5mm tolerance in the rear , what do you mean by this ? , is it a max amount that the front & rear wheels can be offset in track ? . I have bookmarked your thread so that I cannot loose it and will begin to pull together the parts required ( k1100 centre stand etc )

Ta

Ciao

JR Melbourne Australia

nice one jr .......welcome to the forum ...pics ?

Nuh, it was 'Çomber who mentioned the 5mm offset, and I presume he meant track as well. I too searched for a tyre in the near-stock size of 140/80R17 and found nothing that I'd want to use. I get the creeps over Avons, having spent years riding in rainy environments, and seeing their slippery slidey ways. Pardon to those of you who think they're the shit. It's a small time tyre company that's been left in the past, though they were the first to mass-release a motorbike radial tyre in the '80s.

There is not enough room in these models for any more than one single 2mm spacer unless you have an aftermarket exhaust that is slimmer or can move the stock exhaust to the left with a modified mount. There is just enough room on the right hand swingarm side, and I might remove the 2mm spacer...the 4.5x18" 3 spoke K1, K100-16V, K1100RS and R1100 road bike series wheels are a 'dime a dozen', used from about 1988 through the late '90s. But either measure and modify your centre stand or get a K1100 version. This is the way to go, IMHO.

The mention of the 5mm tolerance came from the official BMW workshop manual, A5 sized, thick paperback, if you haven't seen one. Sort of useful to have but wouldn't have paid the £50 they cost if it hadn't came with the bike.
I would guess it means that its OK as long as the rear wheel is within 5mm of the centre line of the front wheel.
I seem to remember an article from beachcomber on the same subject and he seemed to think it was not a big issue if it was within that measurement.

It does mean that, and I have seen it ages ago in a BMW workshop I once worked in, but they're all in CD format nowadays, the newer models at least. The keys on my laptop wear a slight sheen of fingertip grease from my efforts.

The right hand side tyre to swingarm clearance is about the same as when the 140mm tyre was fitted I think due to wheel offset, of about 10mm, it's the exhaust side that's closer, but that could be the shape right there at that spot of my Motad brand exhaust as well. A stock or other aftermarket brand exhaust system might offer more clearance. Also, it would not be too difficult to 'çlearance' the exhaust a smidgen.

I might remove the 2mm wheel to final drive spacer to allow for a tad more space over that side as the easy fix first. Though nothing is wrong with the available clearance. It's just the idea of spinning rubber (read, potentially expanding and/or contracting along with suspension movements) and hot metal being in close proximity (less than 10mm) to one another...

If I had another project bike I would perform this wheel and tyre mod on it as well. It has been well worth it, like the other subtle upgrades I've made. It has not been revolutionary as much as evolutionary, they are not wild changes, and in the end I have a nice, older K100RS with a few improvements which make even it more of a pleasure to ride easier, smoother, faster, and a bike that stops better too.

I think you will find that those spacers are there so as to be able to adjust the alignment to centre they are not meant to adjust the clearance to the exaust.

I left the spacer out accidently at one tyre change and it fell into right hand corners but was a real hand full trying to go into left hand corners or the opposite I can't remember now but I think that is right.

I have built a few frames for drag racing bikes and you have to be very careful to get the alignment spot on or they want to move right or left under hard acceleration. The effect is even worse with a 10" wide slick as it drives across the full width and pushes the bike to the side that the front is set to. If the front wheel is set to the right then it pushes to the right and at 150mph with 200hp the results are to say the least dramatic.

K Freak wrote:I think you will find that those spacers are there so as to be able to adjust the alignment to centre they are not meant to adjust the clearance to the exhaust.

Of course, it would only be removed if the centre line of the tyres is not affected. I proceed with some measure of caution.

[img][/img]

Here she is Charlie99 , picked her up in Germany new in March 1987 then brought her home after 6 months touring , she's my daily ride & now has 242k clocked up , new 3 spoke up front with a Dunlop Roadsmart in this pic , second hand rear with Dunlop D205 ( can't really tell in this pic ) , front discs are "Braking" , Staintune pipe installed in 1989 , Corbin Canyon Dual sport seat , K1100 mirror pod spacers ( also not visible ) , Ikon shock ( hopeless ! ) braided goodridge lines back & front ( and the little bugger under the dash pad ) , AGM PC680 battery .

Ciao

JR Melbourne Australia

sweet !!!!

Those Odyssey PC680 are some battery! I obtained one that had been in use in a cop bike for two years and the mechanic thought it had been losing charge, so he replaced it, Odyssey didn't pay the claim so it sat on our used parts shelf for another 18 months, then the boss was clearing things out and handed it to me where I promptly put it into a succession of Oilheads (three) over the next four years! Last I knew it was running round the streets of Portland Oregon in a blue and black R100RSA owned by a mate of mine who bought the bike from me. That was in 2006. They take a charge with lotsa amps, and can be resurrected from a very low state to near-new. Funny, but we used to buy them for US$79, a true bargain...they can't be touched for almost $300 with postage in OZ.

I had thought of using the 3" K1100LT rear wheel too but wanted a wider tyre than a 140 and again, that limited radial tyre choice issue.

Great history with the bike, JR!

G'day TWB ,
yup agree with you completely on the PC680 , they slot straight in no mods ( just flip over the battery clamp ) got mine from a specialist battery place only a few K's from my home , no more free acid making a mess , but back to your wheel mod if I may , please advise on your final set up ie spacers in or out , tyre pressures and you mentioned you may slide your forks up or down , I fully intend to do this mod to my machine so will be following your progress very closely .

Ta

Ciao

JR Melbourne Australia

Well, I've had the bike on the road like this for six days now, commuting and twisty back road and some motorway riding, sunshine AND rain. She falls into the corners with amazing ease akin to a more modern bike, tracks straight and isn't upset by wiggles and squiggles in the bitumen. Until I change out the short arse Works Performance rear shock to the proper length version I'll leave the forks where I put them a coupla years back, with about 15mm showing above the upper triple clamp. I'm also going to leave the 2mm spacer right where it is and not bother removing it or adding another as the front to back tyre alignment is as spot on as I can tell by running a (fairly) straight edge along them. Tyre pressures I have not sorted just yet as I've not got enough kilometres under them. At the mo' I've squirted 36 psi into the front and 40 into the back, for all solo, relatively low speed/low temperature riding so far.

Right now the grey afternoon sky is dumping a very heavy rain so my ride home from work this evening will be their best test yet on the greasy roundabouts and stoplights in the wet. Let's see how we go!

Verdict: the tyres are bloody beautiful when it's bucketing with rain. No slippery sliding at all, and a confidence-inspiring feeling splashing through deep puddles and on rain-slicked tarmac. 'Tis a pity my waterproof gloves weren't so good at their job.

Thanks for the real world road report mate! I was expecting the radials to be vastly superior in the fowl weather and it sounds like an excellent setup for my neck of the woods.


OG

Oldgoat wrote:I was expecting the radials to be vastly superior in the fowl weather...OG

Let's just say that with the radials fitted I'm no longer chicken when it's weather for ducks even though I know I'm crowing like a rooster, but don't want to be called a silly goose!

Sorry, mate, you left that one wide open.

Get me a gun mah, there's something I just gotta do up in Queensland.

Spell check hunting?

Two Wheels Better wrote:Spell check hunting?

update:-- saw the beast in the flesh today ...and it looks fantastic ...theres lots and lots of rubber squeezed in there at the back ...and not much room for anything else (about 2mm to the exhaust on the lefthand side had to put my glasses on to see that ...giggle ) ....but more rubber on the road can make things way different to what we know already ....good work twb ....cheers !!!

Today is a day off for me, a Monday but my Sunday, whilst the masses are at work toiling away I'm out riding or playing with my motorbikes. I get my turn, yoke round my neck, shoulder shackled to the grindstone Tuesday through Saturday every week. Time for a play.

The too-tight tolerance 2mm Chazza mentions above on the exhaust side had me thinking, a dangerous thing, so I whizzed off the exhaust mount and shortened the two stud 'barrels' that hold the bonded-rubber-metal mount to the footpeg bracket, and straightened the exhaust's top mounting tab, which was bent slightly outward, pushing the exhaust closer to the wider 160mm tyre. It would be no problem with a stock width rear tyre.

I removed 1/3rd from each of the two barrel's length on the bench grinder then screwed it all back together. The metal ground off and straightening the mounting tab has increased the clearance from tyre's edge to exhaust, so now the space there is the same as the swingarm side, about 6mm per side, which is plenty.


The cylindrical barrels in the centre of the exhaust mount are easily ground away to make additional clearance, without compromising the integrity of the mount.


This angle doesn't fully show the 6mm or so space that is available now. The shiny spot and marks are my rubbings trying to measure the space as I changed things.


"Heaps" of room on the swingarm side, the same as there was when using a 140/80VB17 bias ply tyre.

To further the research done in the interest of more and smoother power, after fitting the K1200RS injectors I gave it a good run to the shops over the empty backroads round my bush neighbourhood. She responds and runs sweet. I whizzed out a coupla sparkies and sure enough there's a nice, light brown colour on the tip of the ceramic, proving for the time being that the teeny tiny weeny little bit of extra petrol at each squirt has done the trick. Progress is painful but if measured shows itself in the incremental changes made. I would do all of this all over again to any older K bike I own.

Time to rip the scabs of a coupla coldies and listen to some Bob Marley, the Who, Porcupine Tree and Paul Kelly too.

There's not much to spoil the view.

lol .....good product placement ...ol mate ......the reward at the end of the day ...is always appreciated ....and nicely poured

The trick is to keep a clean, water-washed only glass (never use soap) in the freezer, glug the beer from the bottle into the glass on a tilt then slow down about half way until it's full. If it's gunna run over you've poured too fast so a clean finger laid across the top will help stop the ol' runneth over - we call that alcohol abuse!

The other trick is to drink slowly and enjoy the froth.

should i moove this to the "how too section " ....... sorry left yourself open there mate .

looks great all the same .....ill bet some of our northern friends will never know the bliss of a coldie at the end of the day ....quite like we have here ...cheers you blokes ...one and all

"How too" as in also, or are you secretly craving a coldie as well!

I've a very cold 100cl tin of Kronenbourg in the fridge that's crying out to be opened! Today was that sort of day.

aye !!!!

This is another interesting way to do the four pot caliper conversion http://www.k-bikes.com/forums/showthread.php?t=18156

Yep, their experiences are all pretty much what I worked out too. Except that I used Suzuki discs and aluminium spacers inside of them against the hub to centre the pads and the discs. Also, I gained an additional 7mm per disc in diameter, the brake pads sweeping close to the edge of the disc's surfaces, and the discs hard against the inside of the calipers to almost touch the two 10mm caliper through-bolts. It was worth the trouble.