What size sprocket?

[AtlBanditMan]

Hello everyone, I was hoping you all could help me with some info on Sprockets.

I know most people are looking for more power on take offs. Me myself I want top end. So I was thinking about going down in size on the rear sprocket of my 03 Bandit 1200. To me and it may just be me. But to me when I am riding and I am in 5 gear I always trying to go up one more gear. So I wanted to know has anyone gone down in teeth on the rear of there bike and knows if this will be ok for the bike?

I ask because I had a friend who went up in teeth on the front of his Ninja 600. After he did that, if he was riding his bike on the freeway or any highway speeds after so long it would kill on him and he would have to pull over and what to start the bike. Once he put the stock gear back on the bike it did not do it any more. So I ask only to know before I put the money out on the new sprocket.

Thank for any help.

[Red01]

You can easily drop 3 teeth in the rear - or add 1 up front (requires minor clearancing to the sprocket cover).  These have both been done by many B12 owners looking to drop cruise rpm.  An added plus is it usually makes the speedo more accurate.  You could probably drop more than three teeth in the rear, but this isn't as commonly done and I don't know if there's anyone still here running anything taller than a -3 rear or a +1 front.  (If so, hopefully they'll pipe in.)

One thing for sure, I've never heard of anyone having any kind of troubles like your Ninja friend, no matter what gearing they've run.

[daniel1]

The stock gearing on the bandit is quite high to begin with and the bike does not have the power or aerodynamic shape to pull redline in top gear.  You will probably have higher top speed if you went the opposite way.  The old gixxer 1100's were geared 15/48 and the bandit is 15/45, the 15/48 or 14/45 combo is more in line with the power and shape of the bandit.  If you go the way you are thinking you will get a little lower rpm at highway cruise speeds but I'd bet your top speed would be down.

[AtlBanditMan]

I'm not looking at high top speeds. I'm just looking to slow the RPM's down a few more hundred. I know its going to slow the take off power as well. But the way I see it is I don't like very fast take offs  I'm not looking to do wheedles or any kind of high speed take off. All I'm looking to do is slow the eng. down in the highway. And was worried that it may cause some other things to go wrong.

[CWO4GUNNER]

In that case your still going to achieve the same proportional results. Like stated above, 1 on the front equals 3 on the back so if you want to do it cheap add one tooth to the front and try it, about $13-$25. Of course you could always spend more by dropping 3 teeth on the back which will mean a new shorter chain to adjust for run out trying to accommodate a 3 tooth smaller rear sprocket $40-$100.

I'm not looking at high top speeds. I'm just looking to slow the RPM's down a few more hundred.

[AtlBanditMan]

Ok so if I go one size bigger in the front what kind of clearancing to the sprocket cover or we talking about? I was buy all new sprocket and chair sets so that's why I'm trying to fine out so I will know what to order. If it was to much I was thinking I would not had to do anything to keep the stock up front and go smaller in the back. What way is easer or better I guess is what I really am asking?

I was thinking more along the long of two teeth on the back but I see everyone is saying three. Either size how much am I looking to drop the speed of the eng? As I said before I do want to slow it down but I don't want to hurt the eng. at the same time. So that's why I am asking now before I do something I am sorry for later.

[pmackie]

Either size how much am I looking to drop the speed of the eng

If my math is correct:
stock 15/45 = 0.33333
15/43 = .34884 or 4.65% change
15/42 = .35714 or 7.14% change

Assuming a stock cruising rpm or 4000 then 15/43 = 3814 rpm, 15/42 = 3714 rpm

If you need new chain an sprockets anyway, then going with a smaller rear will make it all a bolt on. Increasing to a 16 front will likely mean some grinding with a dremel tool or similar. Someone on a 1200 should be able to answer.

[Red01]

Your math checks expressing the gearing in the fractions as you typed them, but typically sprockets are calculated the other way around.

15/45 sprockets, expressed as a fraction would be 45/15, or a 3.00:1 ratio.
Think of it this way, since the countershaft sprocket (15) rotates three times for every revolution of the rear sprocket (45).

Therefore:
43/15 = 2.8667:1 (4.44% change)
42/15 = 2.8000:1 (6.67% change)

And if you just bump the countershaft sprocket up one tooth and keep the stock rear:

45/16 = 2.8125:1 (6.25% change)

[Bob Holland]

 15/45

RPM    MPH   MPH   MPH   MPH   MPH
 1,500    9.9   14.5   18.9   22.6   25.9
 2,000    13.2   19.3   25.2   30.1   34.5
 2,500    16.5   24.1   31.5   37.7   43.1
 3,000    19.8   29.0   37.8   45.2   51.7
 3,500    23.1   33.8   44.1   52.7   60.4
 4,000    26.4   38.6   50.4   60.3   69.0
 4,500    29.7   43.4   56.7   67.8   77.6
 5,000    33.0   48.3   63.0   75.3   86.2
 5,500    36.3   53.1   69.3   82.9   94.9
 6,000    39.6   57.9   75.6   90.4   103.5

15/42
 RPM    MPH   MPH   MPH   MPH   MPH
 1,500    10.6   15.5   20.2   24.2   27.7
 2,000    14.2   20.7   27.0   32.3   37.0
 2,500    17.7   25.9   33.7   40.4   46.2
 3,000    21.2   31.0   40.5   48.4   55.4
 3,500    24.8   36.2   47.2   56.5   64.7
 4,000    28.3   41.4   54.0   64.6   73.9
 4,500    31.8   46.5   60.7   72.7   83.2
 5,000    35.4   51.7   67.5   80.7   92.4
 5,500    38.9   56.9   74.2   88.8   101.6
 6,000    42.5   62.1   81.0   96.9   110.9

[Daytona]

 :annoy:If you think it will get better MPG think again! Super slab commuting @ 85 will drop a couple a miles per. Its easy to lug and just ain't worth it. 16 primary is what I tried. It needed that 6th gear.

[Snubnose]

What increments can the rear sprocket go down in size?.. by ones? 2's" or 3's.

I'm looking for slightly lower rpm at high speed, not alot less, but a little without sacrificing too much from take-off. Oh, I also don't want to play with the front sprocket as I have become conditioned to the quieter operation of the OEM rubber dampened stock 15 version.

suggestions?

[Red01]

You should be able to go down on the rear in 1's... but that would be a very small change. 
Remember, 1 tooth up front is ~= 3 in the rear.