A sixth gear for a Bandit 1200...Please

[Desolation Angel]

You know, it seems to me that a GSF is just a real grown up GS, and the GS series bikes had 6 gears, did they not?  So, I wonder if something could be swapped out from the GS1150 transmission to get a 6th gear?  This from a non-mechanic, so I don't know what I'm talking about, but I wish...

A transplant I'd be willing to do!

[tacoman]

Being that the B12 motor came from the gixxers, its original design was for racing and not sport touring.  I had a gixxer 1100 and first gear was very tall, geared for the track.  I imagine if Suz tried to go with a 6th gear there would be durability issues.  Being that the motor has about used up its economic life I don't see Suzuki spending any money on it.  Being that it is chain drive you can always change sprockets if you want better hiway cruising.

[Noonie]

Call me ignorant, or just stupid, but my B6 has 6 gears... Was it just the B12 models with 5?

[Vee Dub Nut]

yes b6's have 6, b12's have five...

[Bob Holland]

I'm running 15/43 gears, and that is about as tall a gearing as you would need. A stock b12 would not be a wheelie king with 15/43, but it would have plenty of torque for that gearing. People use to put the GSXR 750 trans in the GSXR 1100s, but the GSXR trans are not interchangable with the Bandit, but I would think that the 600 Bandit might be.
I had a new under cut GSXR 1100 trans, and when I rebuilt my bandit, I tried to use the complete trans, and it would not fit, I think that the Bandit cases are heavier in the trans area, than the old GSXR.

[Red01]

With the right mix & match of parts, you can build an 1100/1200 motor with a six speed box from a 600/750... but I don't think there's anything to gain. Suzuki didn't give the 1100/1200 six cogs because its torque doesn't need six gears. If you want to lower cruise rpm, just change the sprockets.

All the SACS 1100 & 1200 gearboxes have the same ratios (not all parts are the same from year-to-year, but the ratios are the same):

Primary Reduction Ratio: 1.565
1st: 2.384
2nd: 1.631
3rd: 1.250
4th: 1.045
5th: 0.913

SACS 600/750 gearbox
Primary Reducion Ratio: 1.681
1st: 3.083
2nd: 2.062
3rd: 1.647
4th: 1.400
5th: 1.227
6th: 1.095


From oldskoolsuzuki:

GEARBOXES
1127: Depending on the clutch type there are long and short shafts. Also the gears themsleves from these boxes are different. It may be possible to swap a few gears between these boxes, but the gearchanges might not be very smooth.
Apart from the clutch type, the 91-92 1127R has a double row bearing on the output shaft, and therefore a slightly different crankcase (around the bearing area).

Gear boxes from all 750's are swapable. I have no experience with swapping gears seperately.

The B6 has a different shaft, so it can only be used with it's own clutch.

and

750R 6 box in a 1127 motor
The only hard thing here is to have a hole drilled through the gear box shaft, for the pushrod. The 750 6 boxes have a single row bearing on the output shaft, and the clutch does not have a diaphragm spring. So the easiest 1127 engines to put a 6 box in are the ones with a single row bearing on the output shaft, and no diaphragm clutch, ie. only the GSXF1127 engines. In these engines the 6 box drops straight in, only the shaft has to be drilled.

Second easy would be an 1127R engine with a diaphragm clutch, but no double row bearing (88-90). In this case the box would still drop in, but for the clutch one would have to use the inner clutch parts from a GSXF1127 (with normal springs) and the outer clutch basket from the 1127R (with a straight cut gear, not helical).

Most work is in a 91/92 1127R where one would have to match the clutch as above + find a solution for the double row bearing (the solution is actually to turn the double row bearing inside out, and make a little hole for the small pin). Of course the shift drum and forks from the 6 box have to be used as well, but they drop in any 1127 without problems.