16 tooth disappointment

2100 Views 20 Replies 8 Participants Last post by bbarnier, 1 mo ago

bsouza10x

Discussion Starter · 10 mo ago

I installed a 16 tooth front sprocket today, and I'm a little disappointed.

At highway speeds (75 MPH) my speedometer read +4MPH as verified by GPS and RPM at 75MPH was 6000RPM.

After installing the 16T, speedometer reads the same as before, and RPM at 75MPH only dropped about 300.

I was hoping for 400-500 rpm drop, and some correction in the speedometer, but not what I was hoping for.

Well, so much for hope!

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muzscorpion

· #2 · 10 mo ago

75 mph are exact 120,7 km/h in europe. During the tests
with the sixteen teeth front sprocket on the 650 RS
with the homoligation equiment and datalogger i read
120,12 km/h at 5460 rpm.
The tolerance for the speed is 0,01 km/h and the tolerance for the
rpm are +_ 10 rpm.
The rpm-signal come from the ignition-system and the speed
from Gps with a tolerance from +- 1m for GPS-Signal.Tire pressure
was 3 bar on the front and 3.5 bar on the rear. The rear tire was
brandnew, because the speedsignal for the speedometer from the RS
come from the rear ABS-ring.
Brian, i think you have your drop from 400-500 rpm in real!
But not on the dash... !

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bsouza10x

Discussion Starter · #3 · 10 mo ago

I believe you, but I was using the GPS before and after the sprocket change.
Do you think a 43 tooth rear sprocket would give me the additional 200 RPM change I'm looking for?
Thanks!

muzscorpion

· #4 · 10 mo ago (Edited)

I recommend you max. down to the 43 teeth sprocket in the rear,
gives you 466 rpm more drop...

muzscorpion

· #5 · 10 mo ago

Forget somthing:
16 font and 46 rear: your rpm drop down to 5288 rpm at the speed with 75 mph,
change in the rear down to 43 teeth you get 4822 also with theoretical mathematic
at the same speed with a 160/60 R 17 tyre.

bsouza10x

Discussion Starter · #6 · 10 mo ago

I wonder why my GPS was showing 5800 RPM at 75 MPH? Unless the GPS application on my cell phone sucks.

Either way, maybe a 43T (or 44T?) would be what I'm looking for.

Thank you for your help!
Brian

muzscorpion

· #7 · 10 mo ago

Brian,
for 16t front and 44t rear you get also a "recomended"
at your speed with 75 mp you will have 5009 rpm (theoretical)
Mike

Carvalho Ciclismo Eduardo

· #8 · 10 mo ago

I never touched the oem front sprocket, but changed rear sprocket to a 43t.
The speedometer readings were closer to real and rpm dropped about 500rpm.

muzscorpion

· #9 · 10 mo ago

Changing the number of rear teeth will not change the speedometer reading as the signal for
the speedometer is generated by the rear abs. A change occurs only when the diameter of
the tire changes.

brian.souza

· #10 · 10 mo ago

I've got a 43T rear on order. I'll report back later!

muzscorpion

· #11 · 10 mo ago

I hope that the lenght from the chain is ok,
mean you have to take min 1 compleet link.

brian.souza

· #12 · 10 mo ago

I installed the 16T front, which moved the rear forward, and now with the 43T rear, it will move to the rear, so I think I will be ok.

John2018

· #13 · 9 mo ago

I would not modify the sprockets on the motorcycle. Each motorcycle is designed with a specific purpose.

If you want a motorcycle for Fwy use in the range of 75 ~ 120, 130 MPH get a Suzuki GSXS1000 or a Kawasaki ZH2.

The Suzuki GSXS1000 can cruise at 35 MPH under 3,000 RPM or 75 ~ 80 MPH about 5,000 RPM which makes about 50~ 55 MPG.

mattv

· #14 · 8 mo ago

John2018 said:
I would not modify the sprockets on the motorcycle. Each motorcycle is designed with a specific purpose.

Terrible advice. Modify your motorcycle to your purpose. Be safe and have fun.

Reactions: 3

John2018

· #15 · 7 mo ago

mattv said:
Terrible advice. Modify your motorcycle to your purpose. Be safe and have fun.

Yes, to your purpose of suicide. Do you know how many motorcycle riders get into an accident for modifying their bike in a wrong way? Some are not with us anymore to tell their story.

Motorcycles are already extremely dangerous, modifying it adds more to it, just one screw that one leaves loose and one can get killed.

mattv

· #16 · 7 mo ago

Who do you think assembles your motorcycle?

Reactions: 1

muzscorpion

· #17 · 7 mo ago

John2018 said:
I would not modify the sprockets on the motorcycle. Each motorcycle is designed with a specific purpose.

If you want a motorcycle for Fwy use in the range of 75 ~ 120, 130 MPH get a Suzuki GSXS1000 or a Kawasaki ZH2.

The Suzuki GSXS1000 can cruise at 35 MPH under 3,000 RPM or 75 ~ 80 MPH about 5,000 RPM which makes about 50~ 55 MPG.

If you modify your motorcycle with a larger front sprocket, you only want to reduce the speed and save gas.
It is worse when the engine power is increased and the engine is destroyed during a fast drive and
somebody get a heavy accident and the rider died!!

John2018

· #18 · 7 mo ago

mattv said:
Who do you think assembles your motorcycle?

Competent mechanics who know the motorcycle better than you and me combined.

John2018

· #19 · 7 mo ago

muzscorpion said:
If you modify your motorcycle with a larger front sprocket, you only want to reduce the speed and save gas.
It is worse when the engine power is increased and the engine is destroyed during a fast drive and
somebody get a heavy accident and the rider died!!

The whole point of riding a motorcycle is to have a fast 0-60, a fast take of, otherwise it will be better to drive a car like a grandma.
The Z650 was designed for fast acceleration in mind, if you put a bigger sprocket it will completely ruin the whole purpose of this bike. It will have a horrible take of, any car will beat you in take off.
6K or 7K rpm is just fine 75 ~ 90 MPH. My Z650 makes 115 ~ 120 MPH very quick at top RPM. I just do it for short periods of time, perhaps just to pass a car that is making 100 mph.

eduardopereira5000

· #20 · 5 mo ago

I should have kept 15… and gone to 43 rear.
750rpm less.

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