Sprocket changes up in front down in back

[Shaft]

Has anyone done this? Up in front, down in the back? Looking to get the rpm's dropped a bit for touring. How much of a difference? and fuel mileage?

thanks guys.

[Professor]

On the Gen I bikes swaping to an 18 front is fairly common giving a 18/40 instead of a 17/40. Busawhipped likely has the numbers you are looking for. It puts the speedometer much closer to being correct also.

I'm running 18/41 on the street with mine right now to tame the hit a little bit.

[BusaWhipped]

I have 16/42 on right now for the track. I run 18/40 normally. If I remember correctly, 70 mph is 3500 rpm with the 18/40 setup. Semi is running 18/40 maybe he'll chime in on this thread.

[Stumpy]

dr1300r is also runnin an 18/40....i was running 17/40 and got better mpg then he did on the way to the eureka springs

[Got-Busa?]

18/41 is great for 200mph+ touring...

[Shaft]

nice. I'm definitly looking to do the change.. my bike only has 4700 kms on it. don't wanna do the chain as well.. do you guys think its safe to just change the sprockets and leave the chain alone? i keep it clean and oiled religiously.

I have a speedo healer so calibration will be a sinch!

[BusaWhipped]

nice. I'm definitly looking to do the change.. my bike only has 4700 kms on it. don't wanna do the chain as well.. do you guys think its safe to just change the sprockets and leave the chain alone? i keep it clean and oiled religiously.

I have a speedo healer so calibration will be a sinch!

As long as the chain and sprockets are healthy, you can change one without the other. I swap sprockets a couple of times a year to match the riding I'm doing at the time. Chains usually last me 1.5 to 2 years.

[BusaWhipped]

dr1300r is also runnin an 18/40....i was running 17/40 and got better mpg then he did on the way to the eureka springs

A lot of that depends on the fuel map and the throttle hand. semi and I are both getting around 45 mpg on the highway running the 18/40 setup.

[rusheriv]

A well maintained chain with less than 3,000 miles (4700km), I'd say you're good to go with just the sprocket change.

[Shaft]

busawhipped whats the stock setup on the genII's for sprockets? do you know the Stock fuel consumptions as well?? I miss that on the GEN I. fuel computer built in was always sweet to have.

[Professor]

do you guys think its safe to just change the sprockets and leave the chain alone? i keep it clean and oiled religiously.

Some will argue this. I say check the chain per the service manual. If it is within specs, run it. You should always check it anyhow.


Try this link

https://www.hayabusa.org/forum/engi...-what-chains-do-you-guys-use.html#post1450033

[sixpack577]

busawhipped whats the stock setup on the genII's for sprockets? do you know the Stock fuel consumptions as well?? I miss that on the GEN I. fuel computer built in was always sweet to have.

Stock Gen2 is 18/43

[Professor]

busawhipped whats the stock setup on the genII's for sprockets? do you know the Stock fuel consumptions as well?? I miss that on the GEN I. fuel computer built in was always sweet to have.

The Gen 1 is a 17/40 (112 link chain)
The Gen 2 is a 18/43 (114 link chain)

This is a pretty good site to bounce numbers.

Gearing Commander: Motorcycle Gear Ratio Calculator for Sprockets RPM Speed Chain


Part of the information you are going to get on fuel consumption is going to be flawed unless the riders have calibrated the factory speedometer with each change or adjusted for error. The factory speedometer (and fuel computer) is off and will show better fuel consumpion (more miles) than actual. Most don't make correction for the changes they make to the gearing.
Pretty much you are going to get better mileage at the same MPH if you are turning less RPM. Of course you still keeping within a range the engine is capable of pulling the load. The busa make loads of power down low so that is not really a problem.

[Sous]

I was asking about this a while back due to a lot of highway riding and was sending PM's back and forth with a .org member that went to 19/43 on the Gen II. He said that his RPM's dropped by about 200 at around 65-70 MPH. So, if you drop down on the rear sprocket as well, you could possibly get down to the RPM you are looking for during touring.

[Professor]

A 19/43 will be very close to the 18/41 I am running. I'll do a few calculations.

[Professor]

Here is a ratio of chart of some combinations that come into play.

17-38 2.24
17-39 2.29
17-40 2.35
17-41 2.41
17-42 2.47
17-43 2.53
17-44 2.59
17-45 2.65
18-38 2.11
18-39 2.17
18-40 2.22
18-41 2.28
18-42 2.33
18-43 2.39
18-44 2.44
18-45 2.50
19-38 2.00
19-39 2.05
19-40 2.11
19-41 2.16
19-42 2.21
19-43 2.26
19-44 2.32
19-45 2.37

[Shaft]

wow great information guys.. surely lots to play with on this.

as far as sprockets and quality... where to purchase? and what kind of life are you getting from these sprockets?

[Spkrdctr]

I have 19/43 and it works great! I would not hesitate to do the front sprocket change. It still has too much first gear hit for me. I can't handle it at my skill level. So, I don't whack it wide open in first! Once I hit second, then I go WFO. I need someone to train with on launching the bike hard in first. But, no one around my area.....Tampa Florida.

[Shaft]

sprockets ordered from Tim. Can't wait to do the swap! You guys use an impact on the front sprocket?

[Black Sheep]

Just one tooth either sprocket makes a huge difference. From experience!
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