Front Sprocket Change

[Johnnylane]

Does anyone have an idea what the torque changes to with the change from the stock 16-tooth front counter sprocket to the 15-tooth? This for a 2007, US FZ6.

I believe the stock 16-tooth delivers 46.5 foot-pounds at 10,000 rpms. What happens to the torque when the 15-tooth sprocket is installed?

[mattcosta7]

Originally Posted by Johnnylane

Does anyone have an idea what the torque changes to with the change from the stock 16-tooth front counter sprocket to the 15-tooth? This for a 2007, US FZ6.

I believe the stock 16-tooth delivers 46.5 foot-pounds at 10,000 rpms. What happens to the torque when the 15-tooth sprocket is installed?

It doesn't change the torque delivered, it just makes the torque applied at a lower rpm. I'm not sure the exact figure, but since you're revving the engine higher to hit the same speeds, you are likely to spend more time in the powerband, and thus feel more torque at lower speeds

[DefyInertia]

you just get more thrust, that's all.

[sledjeski]

The available torque at a given engine speed and gear is determined by the engine output, the transmission ratio, and the final drive ratio. I think the stock final drive is something like 16/46; going to a 15/46 will result in about 7% additional torque with the engine speed and gear selection being equal.

At a given motorcycle speed, say 65 mph on the on ramp curve. You get the 7% from the gearing "plus" the extra torque the engine is making due to the increased rpm needed to achieve this motorcycle speed. It's the most economical performance (acceleration) enhancement - you get the benefit as soon as the clutch is engaged.

[DefyInertia]

Originally Posted by sledjeski

At a given motorcycle speed, say 65 mph on the on ramp curve. You get the 7% from the gearing "plus" the extra torque the engine is making due to the increased rpm needed to achieve this motorcycle speed.

That's kind of a misleading way of explaining it...at least for me it is.

Your HP and torque curves will look exactly the same...they will simply occurs at slower speeds (top speed in each gear will be lower). It's like having a bigger lever...more leverage to put power down.

You simply wind the bike out faster but it's not due to a power or torque increase.

[urbanj]

Originally Posted by Johnnylane

Does anyone have an idea what the torque changes to with the change from the stock 16-tooth front counter sprocket to the 15-tooth? This for a 2007, US FZ6.

I believe the stock 16-tooth delivers 46.5 foot-pounds at 10,000 rpms. What happens to the torque when the 15-tooth sprocket is installed?

I was reading up on what every had to say about the front sprocket as I anxiously wait for mine to come and I wanted to clarify.

The stock ratios in say first gear are 2.8 for 1st gear 1.955 for primary reduction and 2.875 for secondary reduction. Which is your front and rear sprockets.

That's a total multiplication of 15.7:1

When the transmission is in first gear at 10000rpm engine speed, the rear wheel is spinning at 10000rpm/15.7 = 636.9rpm and 730 ft. lbs. (46.5ft. lbs*15.7) are being applied to the rear wheel's axis.

now when you go down -1 on the front sprocket you get at total gear reduction of 16.8:1. Which would mean at the same 10000 engine rpm the rear wheel is spinning 595.2rpm (10000rpm/16.8) and torque applied is 781.2 ft. lbs. at the rear wheel's axis.

But now you are traveling slower but with more torque applied at 10000rpm in 1st gear with a 15 tooth front sprocket.

to go the same speed you would have to rev the engine up to 10700rpm

636.9rpms / 595.2rpms = 1.07
16tooth 15 tooth


1.07*10000rpms =10700rpms for the same rear wheel speed.

except now torque applied will be different because the engine make peak torque at 10000rpms. At 10700 it may be 40 ft. lbs. instead of 46.5. I don't know.

So you can see how the gearing does affect the actual torque being applied to the ground through reduction and thus limits traveling speed due to the slower rpms of the rear wheel.

the 180/55/17 has an approx. circumference of 198.6 cm or 1.986 meters. Multiply that by the stock ratios calculated rear wheel speed of 636.9rpm and you get 1264.88 M traveled per minute or 74746m per hour = 74.7km/h.

with a -1 front sprocket at 10000rpm you will be going 69.9km/h

(1.956m * 595.2 rpm *60minutes = 69.9km/h

Check it against the gearing commander site and you'll see it's correct. Neat huh?

I am by no means an engineer so anyone that is can chime in. But I'm fairly confident in my theory even though I leave out a lot an engineers precise calculations.

[OneTrack]

Sooooo......
You're saying that going -1 in the front is a good thing........right?
I'm also going to try a 15t front sprocket....What the heck, for $40 it's worth a try and is a mod that's easily reversed if I don't like it.
Edited to add: Where are you getting your 15t front sprocket from?

[jniedermeyer]

Originally Posted by OneTrack

Sooooo......
You're saying that going -1 in the front is a good thing........right?
I'm also going to try a 15t front sprocket....What the heck, for $40 it's worth a try and is a mod that's easily reversed if I don't like it.
Edited to add: Where are you getting your 15t front sprocket from?

kneedraggers
http://www.kneedraggers.com/details/...6--623469.html

[urbanj]

Yeah it sure looks like it is and everyone swears by it. In sixth gear looking at the speeds and rpms it's only a 450rpm or 8km/h difference. Which I think is a non factor and you get all the extra pep. I was just clarifying for the OP who asked how the torque changed.

I just ordered a AFAM one from Bayside today. They said 5-10 business days and it cost me $52.37 taxes in. No shipping needed as I'm going to pick it up. I'm hoping the speedo healer will come at the same time and then I'm in business

EDIT: I ordered the AFAM one because I didn't read to much about them being used on our bikes. They seem like high quality stuff and it was only $10 more.

[OneTrack]

Originally Posted by jniedermeyer

kneedraggers
Vortex Racing Front Sprocket - 530 - Yamaha FZ6 - Fits 2004 to 2007 Models - KneeDraggers.com

Yes, I wanted to order one from Kneedraggers, but the calculated shipping cost made it prohibitive , so I'm ordering one from Bayside Performance locally.