Author Topic: OK- gearing question (Read 12753 times)

leedogg · « **on:** May 31, 2007, 05:41:50 PM »

I know that you swap srockets to change the gearing on bikes- what is out there for our bikes. I find myself cruise 70+ quite regularly and that is pushing 4000 rpm...I am certain that a little less rpm's would make it alot sweeter on the open road.

What do you have to do to correct the speedo afterwards? i noticed that my speedo reads fast anyways- i would like it to be accurate.

Would it be possible to get the 70-75 mph range down to say 3000 or so rpm, without killing the take off. the bike pulls way hard in first now- I never plan on doing wheelies or the such- so the down low isn't as important to me. I take off in 2nd a good bit just to eliminate having to shift right away as it is.

ZenMan · « **Reply #1 on:** June 01, 2007, 01:03:49 AM »

Mine reads 72mph at 3700rpm in 6th gear... that's pretty low rpm's for 70+ in my opinion, and your'e at peak torque (85 ft-lbs).

But it does pull 80ft-lbs at 3000rpm's, so going down a couple teeth on the rear would probably still leave you in the "fat" range.

I'm happy with mine the way it is, though. I can lug it down to 50mph in 6th, crack the throttle and it just jumps up and goes.

leedogg · « **Reply #2 on:** June 01, 2007, 01:33:06 AM »

Quote from: "ZenMan"

Mine reads 72mph at 3700rpm in 6th gear... that's pretty low rpm's for 70+ in my opinion, and your'e at peak torque (85 ft-lbs).

But it does pull 80ft-lbs at 3000rpm's, so going down a couple teeth on the rear would probably still leave you in the "fat" range.

I'm happy with mine the way it is, though. I can lug it down to 50mph in 6th, crack the throttle and it just jumps up and goes.

50- hell I can get down to about 42 or so- and it'll pull fine with my 320 lb butt on it! OK so maybe 4000 is 80mph indicated...still way too high IMO...I just start to feel the buzz of the engine after about 30 minutes of that.

ZenMan · « **Reply #3 on:** June 01, 2007, 03:16:06 AM »

You feel a buzz? I sure don't on mine... but I have yet to ride it for more than a 2 hour stretch.

Well considering the old Bandit with the 5-speed was running a little over 4000rpm's at 70mph, and the SACS motor was notorious for buzzing in the mid-range, I'd say the B1250 is quite an improvement (no offense, B12 guys!).

I swear I have yet to feel any buzz at all, maybe it's the foam grips... ?

Go ahead, drop a couple teeth on the rear, you can always go back, and I'd be interested to hear how you like it. Not sure what sprockets are available, but it wouldn't suprise me if it was interchangeable with the 2nd Gen Bandits.

leedogg · « **Reply #4 on:** June 01, 2007, 09:22:51 AM »

it's not a heavy buzz...just enough for me to notice. I will do some researching to see if I can find anything...so far finding the aftermarket for the new Bandit has been scarse(sp).

Red01 · « **Reply #5 on:** June 06, 2007, 01:18:48 AM »

Is the stock gearing on the 1250 the same as the 1200?
(15/45 or 3:1)

While you could gear it to turn 3K @ 70, that's a pretty big change and take-off might be more challenging, especially up a steep grade.

The 1200 will handle a tooth up on the front (16/45 or 2.81:1) or -3 on the rear (15/42 or 2.8:1) OK, but more than that is usually not done.

Remember, this isn't an American V8, it's a little DOHC 16V four popper. So, even though the 1250 is torquey for a bike, it still likes RPM more than the average OHV V8 car motor and at 4K RPM, you're not even half way to redline.

leedogg · « **Reply #6 on:** June 06, 2007, 01:32:16 AM »

I prolly just need to get used to it..but it just seems like it is high rpm for cruising...think red is right...I am used to cars I suppose.

Spinmon · « **Reply #7 on:** June 06, 2007, 05:43:47 PM »

Leedog,

I just got this bike as a replacement for a 800cc Suzukii Volusia. I know the vibration that you're mentioning. I've only had the bike for a few days and out for 150 miles. I asked a sportbike friend about it and he rode the bike around the block. He said is was smooth as silk to him, but he didn't want to push it. I told him to take it further and let me know. When he came back, he called it a "frequency vibration" not an engine vibration. I guess since I've been used to cruiser twins and 2 stroke singles, I didn't realize that fours produce a certain vibration naturally as a nature of the engine. Sort of like the buzzy sounds you hear from 4 cyl import cars. I'm a muscle car guy too. I've got an '01 Z 28 and the vibe is definately different!

After riding a cruiser the past few years I went into this thinking that the rpm's were high at 80mph, but really that is less than half of redline. The engine doesn't even break a sweat at 90 mph. As configured, the engine's piston speed works out to about 3980 feet per minute, so that is well below the industry limit of 4500 fpm for street engines (racing engines typically hover around 6000 fpm, but need to be rebuilt after a race or two).

This engine should be able to last forever with relatively little piston wear or valve float, even if you ride it at 9500 rpm all day long!

leedogg · « **Reply #8 on:** June 06, 2007, 11:38:43 PM »

Thanks for letting me know that I am not the only one...thought I was going crazy.LOL

pmackie · « **Reply #9 on:** June 06, 2007, 11:41:32 PM »

If it make you feel better, my little 600 cruises at 6000 rpm at 110 kpmh. For most of it's time on the highway or twisty stuff it is running at 7000 or above (with the occasional run up to 11,500

)

leedogg · « **Reply #10 on:** June 07, 2007, 01:10:48 AM »

ok just playing with the #'s.... if 4000 is 80- the sprockets sets suggested would lower the 80 mph to 3720. not bad.

Then just for giggles- I thought what if you done a 16/42...that'd net you a 2.625- with would put you at 3500 at 80. It would be a 12.5% reduction in gearing.

So, in my way of thinking, that isn't alot. So I am kicking around the idea of getting the -3 for the rear...and see how I like it...then go from there.

This is still down the road a bit though. And no one answered the speedo question. How do you correct the speedo after a sprocket change? I think I read somewhere, on here, that the front wheel gives the speed...so maybe no changes are needed?

leedogg · « **Reply #11 on:** June 07, 2007, 01:13:01 AM »

Quote from: "pmackie"

If it make you feel better, my little 600 cruises at 6000 rpm at 110 kpmh. For most of it's time on the highway or twisty stuff it is running at 7000 or above (with the occasional run up to 11,500 )

ha- if I ran mine up to 11,500- I would be picking up the pistons out of the road!LOL

I just have a hard time with it cuz I think it is torquey that the higher rpm is unnessasary. it detracts from the ride to me. Honestly I prolly won't mess with it for a while- just wanting to learn how it works.

Bob Holland · « **Reply #12 on:** June 07, 2007, 09:18:17 AM »

B1250
TRANSMISSION
6-speed constant mesh

PRIMARY DRIVE RATIO
83/54 (1.537)

FINAL DRIVE RATIO
43/18 (2.388)

I do not have the trans gear ratios for the Bandit 1250, but it is possible that they are the same as the Hayabusa, if not they should be close.
The primary ratio is the gear on the crankshaft/clutch basket

Hayabusa 6 speed constant mesh Gear ratios :
1 - 2.615
2 - 1.937
3 - 1.526
4 - 1.285
5 - 1.136
6 - 1.043

B1200
TRANSMISSION
5-speed constant mesh

PRIMARY DRIVE RATIO
72/46 (1.565)

1st gear (31/13) 2.384
2nd gear (31/19) 1.631
3rd gear (25/20) 1.250
4th gear (23/22) 1.045
5th gear (21/23) 0.913

FINAL DRIVE RATIO
45/15 (3.000)

ZenMan · « **Reply #13 on:** June 07, 2007, 11:16:56 AM »

Compared to the B1200, 1st and 2nd are about the same, 3rd and 4th are a little taller, 5th is about the same, and 6th is overdrive.

Honestly, I don't see much point in going any smaller on the rear sprocket... 4000rpm at 80mph is just loping along as it is.

Now if you went a bit bigger on the rear, I bet you could get redline in 6th... maybe 170 mph?

leedogg · « **Reply #14 on:** June 07, 2007, 01:15:37 PM »

all good info. according to that graph- it appears that the B12 and B12.5 trans is the same ratios- with extra gear for the 12.5.

Maybe something is wrong with my bike- I just don't like the way it feels at those rpms....not cruising.