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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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 Posted: Sat May 24, 2008 8:32 pm Post subject: For those "Searching for Sixth Gear" |
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Just got my final drive with the 2.54 Cruiser gear installed put on the bike this past week.
It's a relief to get the gearing where it deserves to be. Calmed the whole bike down at highway speeds.
I also put new tires on it. Went with bias ply types, for the first time in probably 20 years. Slightly harsher ride, but more stable and less "flickable" if you can use that term with a K-bike. I switched form a 150/70R17 to a 140/80-17 rear. Taller tire but I haven't checked to see how much it has affected my speedometer.
The speedo was pretty accurate with the 150/70 tire at highway speeds. I have made no other changes and now it reads 3500 rpm at an indicated 60 mph, 4000 at 70 and 4500 at 80. I can do a rev limited 60 mph in low gear, 90 in second and 115 in third. Didn't have the room to try fourth. With my old tall transmission gearset installed it would read 3600 at 60, 4200 at 70 and 4800 at 80. So the change in final drive gear is maybe closer to 12%.
The swap is really straightforward if you can find a used final drive for the now out of production R1200C cruiser. It can be done with no extra mods to either the monolever or paralever type final drives.
I have always felt that the stock gears on all the K's were intended for trailer pulling, hill climbing or drag racing. They have needed a sixth gear, in my opinion, from the start. This mod gets you there and can be done without extraordinary expense. The bearings, shims and seals are all interchangeable between all models. I expect about a 5 mpg increase from what I was getting with my drag race setup.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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abreeze
Flying Brick Rider
Joined: 17 Jun 2006
Posts: 671
Location: atlanta
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| Posted: Sat May 24, 2008 9:23 pm Post subject: |
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| do you think a k1200lt final will work?? Ive heard some final are not compatible?? but I dont know...... |
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owrstrich
Flying Brick Rider
Joined: 29 Oct 2006
Posts: 2566
Location: CheezConsin
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| Posted: Sat May 24, 2008 10:47 pm Post subject: |
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good find duckbubbles...
im happy with the stock 6 gears... but if swapping my 6th gear with a r1200c
6th gear is the trick to 5 more mpg... i can see the payoff...
thanks...
j o
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yeeeeeehaaaaaaa... |
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Flying Duck
PsyKotic Waterfowl
Joined: 27 Jan 2005
Posts: 10102
Location: Bumf***, WA
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| Posted: Sat May 24, 2008 11:00 pm Post subject: |
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When they built the 4 valve Ks they did actually make 5th gear a wee bit taller than it was on the 2 valves while 1-4 stayed the same. So it's actually like 5+1/4 gear on our bikes. 
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE |
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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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| Posted: Sun May 25, 2008 12:07 am Post subject: |
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| owrstrich wrote: | good find duckbubbles...
im happy with the stock 6 gears... but if swapping my 6th gear with a r1200c
6th gear is the trick to 5 more mpg... i can see the payoff...
thanks...
j o |
Actually, the transmission is the same, 5 gears. What I did was replace the ring and pinion gear in the rear end, final drive unit. Every gear is taller in overall terms, but I still only have five. The change is equivalent to the difference that having a 6th gear would make. I hope that is clear.
A K1200LT rear gear would work, but I believe that the LT gets it's long legs, tall gearing, in 5th gear by having a special ratio in the transmission, like an overdrive.
My gas mileage was around 45 before I put this "new" transmission in. That is with my original special gears. With the new tranny and the 2.91 rear gear ratio final drive, I was getting 39-40 and spinning the engine too high in my opinion (70 mph was about 4800 rpm). Since I am now close to where I was originally in the gears, I expect to see 45 mpg again.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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| Posted: Sun May 25, 2008 12:21 am Post subject: |
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| Flying Duck wrote: | | When they built the 4 valve Ks they did actually make 5th gear a wee bit taller than it was on the 2 valves while 1-4 stayed the same. So it's actually like 5+1/4 gear on our bikes. |
I got curious about that and looked up the parts on Real OEM.
It appears that the input and intermediate shafts are the same, K1002v and K11004v. There is a difference in the part number of the fifth gear on the output shaft which would seem to indicate a change in ratio. But fewer teeth (to make a taller ratio) would take a smaller diameter gear since the other two remain the same. And that would require different spacing between the intermediate and output shafts. I don't know what the answer is. If somebody has access to a spec chart that lists the separate ratios, that would answer the question.
I am pretty sure that the ratios are listed in my original owners manual. I'll look it up soon.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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| Posted: Sun Jun 01, 2008 11:28 am Post subject: |
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I finally got to run through most of a tank of gas with the new ratio final drive in the bike.
The results were, 198 miles, 4.4 gallons of gas, or 45 mpg on the nose. That is a 12-14% increase over the 39-40 mpg I was getting with the 2.91 rear gear.
What is of interest to me is that the gear ratio change is from 4.83 (overall in fifth gear) to 4.22 (with the 2.54 gear) or 13% change. Could it be that mileage changes in direct relation to gear ratio change? It appears so, in this case at least.
It's just nice to get the mileage back to where I know it will normally be.
I ran through a tank of gas last weekend. But it wasn't a representative sampling as I saw 125 mph a couple of times and did lots of large throttle accelerating. The mileage turned out to be approximately what I was getting with the lower geared final drive or a little less.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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PHIL1601UK
Big Brick Rider
Joined: 01 May 2007
Posts: 64
Location: Bristol, UK
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| Posted: Sun Jun 01, 2008 6:57 pm Post subject: |
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Hi duckbubbles,
Did you perform this mod yourself? Does it make any difference to the bike when pulling away from standstill? Any chattering fom the gearbox?
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1996 Aspen Silver K1100LTSE - acquired 23/03/07 |
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Flying Duck
PsyKotic Waterfowl
Joined: 27 Jan 2005
Posts: 10102
Location: Bumf***, WA
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| Posted: Sun Jun 01, 2008 7:09 pm Post subject: |
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| duckbubbles wrote: | | Flying Duck wrote: | | When they built the 4 valve Ks they did actually make 5th gear a wee bit taller than it was on the 2 valves while 1-4 stayed the same. So it's actually like 5+1/4 gear on our bikes. |
I got curious about that and looked up the parts on Real OEM.
It appears that the input and intermediate shafts are the same, K1002v and K11004v. There is a difference in the part number of the fifth gear on the output shaft which would seem to indicate a change in ratio. But fewer teeth (to make a taller ratio) would take a smaller diameter gear since the other two remain the same. And that would require different spacing between the intermediate and output shafts. I don't know what the answer is. If somebody has access to a spec chart that lists the separate ratios, that would answer the question.
I am pretty sure that the ratios are listed in my original owners manual. I'll look it up soon.
Frank |
A guy who recently bought a K100RS4V tranny from me told me the difference was 1.61 as opposed to 1.67 which is why he wanted to put a 4V tranny(same gears as K11) on his K75.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE |
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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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| Posted: Mon Jun 02, 2008 6:11 pm Post subject: |
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| PHIL1601UK wrote: | Hi duckbubbles,
Did you perform this mod yourself? Does it make any difference to the bike when pulling away from standstill? Any chattering fom the gearbox? |
I don't have the special tools to take the pinion gear out of the gearcase, so I had a long time tech/friend do it for me. He didn't charge me anything, yet. I'll have to do something for him in return.
There are really no problems taking off from a stop, uphill or anywhere else. You'll get used to it in 5 minutes. The 1100's have enough torque to handle it without drama. Even my original 2 valve K100 engine didn't struggle with similar gearing.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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PHIL1601UK
Big Brick Rider
Joined: 01 May 2007
Posts: 64
Location: Bristol, UK
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| Posted: Mon Jun 02, 2008 7:26 pm Post subject: |
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Hi again Frank,
When you say "get used to it in 5 minutes", what is there to get used, or what difference would I notice initially?
You mentioned switching from a 150/70R17 to a 140/80-17 rear - I'm looking at tyre options myself. To answer the effects of different tyres (doesn't take into account load or tyre pressure):
140/80 VR17 - rolling radius = 327.9mm - Circumference = 2060.256459mm - wheel revolutions per mile = 260.3792345 - speed at 3600rpm = 60mph
150/70 VR17 - rolling radius = 320.9mm - Circumference = 2016.274163mm - wheel revolutions per mile = 266.0590558 - speed at 3600rpm = 58.719mph
160/60 VR18 - rolling radius = 324.6mm - Circumference = 2039.521948mm - wheel revolutions per mile = 263.0263433 - speed at 3600rpm = 59.396mph
The last one being the K1100RS rim.
Phil.
_________________
1996 Aspen Silver K1100LTSE - acquired 23/03/07 |
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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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| Posted: Mon Jun 02, 2008 11:31 pm Post subject: |
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| PHIL1601UK wrote: | Hi again Frank,
When you say "get used to it in 5 minutes", what is there to get used, or what difference would I notice initially? |
The point I was trying to make is that, yes, there is some difference, but you will probably forget about it after you use it a little bit.
Now, if you are two up, running very heavy and pulling a trailer or two, the initial start may be more of a problem. It's NOT like trying to take off in 2nd gear, but something in between. If you are having trouble getting going with the stock gearing, don't attempt this mod.
I have always liked tall gearing on my bikes. I left the stock gearing on my Ducati when everybody else in the world said I should add a couple of teeth to the rear sprocket. The real payoff is going down the road with the bike feeling a whole lot calmer, relaxed. I hope that explains it for you.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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PHIL1601UK
Big Brick Rider
Joined: 01 May 2007
Posts: 64
Location: Bristol, UK
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| Posted: Tue Jun 03, 2008 1:15 pm Post subject: |
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Yes it does, thank you. I read somehwere that someone else performing this mod was told by his mechanic that he wouldn't be able to use the 5th wheel bolt in the centre of the hub, any substance in this?
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1996 Aspen Silver K1100LTSE - acquired 23/03/07 |
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duckbubbles
Flying Brick Rider
Joined: 01 Jun 2006
Posts: 361
Location: Austin, Texas, USA
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| Posted: Tue Jun 03, 2008 7:47 pm Post subject: |
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| PHIL1601UK wrote: | | Yes it does, thank you. I read somehwere that someone else performing this mod was told by his mechanic that he wouldn't be able to use the 5th wheel bolt in the centre of the hub, any substance in this? |
That is correct. The center of the crownwheel hub is hollowed out, maybe an attempt to reduce weight.
I wouldn't be too concerned about losing the center bolt. I knew a couple of K bike owners years ago that had turbo setups making 150+rwhp. They used the original four bolt rear wheel setup and had no problems. And they used the 150+hp all the time.
Also, I think the figures for the different tire sizes you quoted may not be entirely correct. Were they calculated? The 140/80-17 tire I put on is quite a bit taller than the 150/70 I took off, judging by the extra lean of the bike on the sidestand. Different brands and even different models of tire from the same manufacturer can have quite a bit of difference between them. I haven't made any measurements, I'm just judging by the lean angle with no other changes. I need to borrow a buddy's GPS to check my speedo again.
Frank
_________________
85 K100/1100RS, 321,000 miles, 25 years
96 Ducati 900SS/SP, sold it
05 R1200ST, 35,000 miles, 5 years
400,000 BMW miles |
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pulhamdown
Joined: 11 Nov 2010
Posts: 7
Location: TAYSIDE, SCOTLAND
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| Posted: Fri Nov 12, 2010 11:07 am Post subject: |
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Hi. I`ve only just discovered this thread. I couldn`t work out how the final drive ratio of 2.54 was arrived at, since virtually every reference on the net said the bevel drive was 33:11. Clearly this gives a ratio of 3.0. By a stroke of luck, I have had a cruiser rear end lying in the garage for several years, so I`ve pulled it apart, counted the teeth, and discovered that the bevel drive is actually 33:13. That makes 2.5384 or 2.54. My next job is to get the bevels transferred into my K1100 bevel box, and then look forward to a drop in revs of around 800 rpm for any given road speed. I have a 15inch rear wheel currently, and am doing 5000 rpm at 60 mph! Thanks for the info. Great site
Colin
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K1100 LT with VELOREX S700 SIDECAR |
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Karlos11
Flying Brick Rider
Joined: 05 Feb 2008
Posts: 188
Location: Portugal, Europe
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| Posted: Sat Nov 13, 2010 5:16 am Post subject: |
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Can you post some photos? I'd never heard of the 2.54 Cruiser. Not sure what it is (language barrier  ).
Sometimes, even in my K11 RS, I think it ought to have a 6th gear. I rode a K11 LT once and the feeling was the same. Basically that's what it is, a feeling. Fuel consumption wise, e.g., I believe K bikes are more economical the Hondas ST1100 (which I also love, sorry  ).
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Carlos
'95 K1100 RS
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pulhamdown
Joined: 11 Nov 2010
Posts: 7
Location: TAYSIDE, SCOTLAND
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| Posted: Sat Nov 13, 2010 9:29 am Post subject: |
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| Karlos11 wrote: | I'd never heard of the 2.54 Cruiser. Not sure what it is (language barrier ).
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Hi. I think there is a bit of language confusion here! The bevel drive gears are from a standard BMW R1200C Cruiser. The bevel gear ratio is 2.54 :1. I hope this a bit clearer.
Colin
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K1100 LT with VELOREX S700 SIDECAR |
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PHIL1601UK
Big Brick Rider
Joined: 01 May 2007
Posts: 64
Location: Bristol, UK
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| Posted: Tue Nov 16, 2010 4:59 pm Post subject: For those "Searching for Sixth Gear |
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| Quote: | | By a stroke of luck, I have had a cruiser rear end lying in the garage for several years, so I`ve pulled it apart, counted the teeth, and discovered that the bevel drive is actually 33:13. That makes 2.5384 or 2.54. My next job is to get the bevels transferred into my K1100 bevel box, and then look forward to a drop in revs of around 800 rpm for any given road speed. I have a 15inch rear wheel currently, and am doing 5000 rpm at 60 mph! |
I'd be interested to ear how it works out if you complete the mod Colin ....
Phil.
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1996 Aspen Silver K1100LTSE - acquired 23/03/07 |
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pulhamdown
Joined: 11 Nov 2010
Posts: 7
Location: TAYSIDE, SCOTLAND
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| Posted: Tue Nov 23, 2010 3:39 pm Post subject: Re: For those "Searching for Sixth Gear |
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| PHIL1601UK wrote: |
I'd be interested to ear how it works out if you complete the mod Colin ....
Phil. |
I`m just sending off my bevel boxes to a friend tomorrow to get the bevel gears swapped over. Should be on the road in the next few weeks. Needs to be road tested before going to the Elefantentreffen, and the Tauerntreffen at the end of January.
Colin
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K1100 LT with VELOREX S700 SIDECAR |
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Shoganai
Biscuit Fluffer
Joined: 27 Apr 2005
Posts: 2234
Location: Culpeper,VA
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| Posted: Tue Nov 23, 2010 10:59 pm Post subject: |
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I have a question...
Why is it so hard or not possible to recut a new transmission?
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1993 K1100RS aka The Shop Whore
1994 K1100RS aka Blue Streak
The long road is a rainbow and the pot of gold lies there.
So slip the chain and I'm off again,
You'll find me everywhere. I'm a Rover. - JT
Nana korobi ya oki |
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