Sprocket

[jamesfz6]

If you compare the FZ6 with a sat nav the speedo is way off. 2-3 mph at speeds of 30 - 40 mph. At 153mph speedo reading my sat nav gave me 142 mph. I found that at 75mph and above the error was between 9 - 11 mph.
The speedo is off IMO. I guess the only way of really knowing is to ride side by side with wavex and she what his speedo computes.

Nelly

Im not saying the speedo doesnt get off. I have never seen a digital be 100% accurate above 80-85mph. I just know that with the sprocket change it hasnt affected the speedo so that i cant travel the speed limits with confidence. If im going fast enough for the speedo to read 150 or higher, im no worried about accuracy im worried about keeping my eyes out for the cops.:thumbup:

 

[Guitar Man]

From an book extract found on the web


"Here is a simple question for you: when does most engine wear occur, at low or high rpm? Contrary to popular belief, the answer is neither, as 70% of ALL engine wear occurs on startup and up to the time the engine reaches running temperature. The remaining 30% of wear occur during normal mileage..."

So yes, in theory, higher rpm means higher wear, but back to the original topic; whether -1 in the front will have a noticeable impact on engine wear or not... I would still say it's negligible.

Your right on that one. The majority of engine wear happens at start up. I push my cars and bikes around the driveway when I am working on them. I don't start them up everytime I need to move it a few feet. And it's good excersise.

The R6's are one tooth lower on the front than our bikes also and have the same rear sprocket. So I guess that means their engines will crater faster than ours. At higher RPM's the extra wear is negligible. Not enough to worry about.

 

[Tailgate]

From an book extract found on the web


"Here is a simple question for you: when does most engine wear occur, at low or high rpm? Contrary to popular belief, the answer is neither, as 70% of ALL engine wear occurs on startup and up to the time the engine reaches running temperature. The remaining 30% of wear occur during normal mileage..."

.

True, cold starts do take a toll. I recommend keeping RPM's low during warm-up (I guess this runs counter to author's quote above).

 

[ItalFreak]

In using the stock information for my 2004 FZ6 at 16/46 I found the calculator to be way off what actually appears on the tach of the bike at 60mph which is the easiest place to get a read because 4th gear at 60 is heads up, 60mph and 6,000rpm. .

What do you mean "way off". At 60 Mph in fourth gear it says 6096 RPM.

You read 6000 so that is a difference of 1,6% !!!
I would not call that way off. And that difference is the inaccuracy of reading the tach.

So actually it is spot on.

Regards, ItalFreak

 

[OkieDavid]

Here's a formula that you can use to determine if your odometer is reading correctly (and if it's not- how far off it actually is) using known distances and a stopwatch. This technique is dependent on maintaining a constant speed as the accuracy depends on it and uses the mile markers on interstates or county roads as your guides. We know that in simplest terms- traveling at 60mph for 60 seconds equals one mile.....For other speeds use the following formula.

Divide 3,600 by the elapsed time in seconds that it took to go one mile and that'll give you your actual speed. For example, say you made your one-mile run at a speedometer reading of 60 mph, and your one-mile elapsed time was 50 seconds. Dividing 3,600 by 50 equals your actual speed of 72 mph.

Apologies in advance to our metric friends......to do this, you'll have to select mph on your speedometer.

 

[KUMAJ]

Please teach me, now I'm confused.
I don't have a beef on accceralation, though prefer to have much more fat midrange. At the time that I riding in winding or twisty road, I'm feeling 2nd gear and 3rd gear riding feels too different character each other. I mean that some time my brain confused in riding to adjust how open throttle or close throttle timing on 2nd or 3rd gear and, I wanna let these be "close gear raito". Should I mod it to "17 and 45" or "15 and 47"???

On my calicuration, of cource magnification raito of "each gear" is not changed but delta is different. If I choose 17 and 45, It looks closed-transmission on delta. Is it true?

I'm little tired to consider something for compensating my riding skill... I should take riding class in closed truck....

 

[urbanj]

does anyone know how far off is the indicated speed compared to actual speed via gps?

 

[ENSU3]

does anyone know how far off is the indicated speed compared to actual speed via gps?

I'd guess +/- 2% seeing how technology has improved so much over the years, they are pretty much dead on now I would think.

 

[HavBlue]

No. It is measured through the transmission. So when you change the output shaft speed (meaning with a smaller sprocket it has to turn faster to go the same speed) you will read a little faster.


On a side note i did a test yesterday and the speedo isnt really that much off. All the way up to 80mph the speedo matched my car.

OK, lets try this, the engine spins and through reduction the transmission spins but at a different rate. Now, lets say there is no counter sprocket on the end of the output shaft, does it change the relative speed the output shaft is turning? No, of course not, you haven't changed anything in the transmission to increase or decrease the rotational speed of the shaft. When you go from the 16T to the 15T it doesn't change the speed of that output shaft but if you measure the rotational speed of the outside of that 15T gear it will be faster because the outside diameter of the gear is smaller and the closer you get to the inside of that gear the faster that rotational speed will become. The modern speedo is measured through use of a pick-up and a PM generator.

 

[FZ6Pilot]

does anyone know how far off is the indicated speed compared to actual speed via gps?

Just checked mine 80mph indicates = 75mph GPS. This was "a rough estimate" because my gps indicates in tenths MPH. So the speedo shows 80MPH - could be anywhere from 74.5 to 75.5 on the gps (the speedo rounds to nearest whole #)

80/75 = 1.0667 (speedo reads 6.67% fast) If the speedometer is using a sensor on the output shaft, then changing the sprocket from a 16 to 15 tooth should give you a true speedometer reading.

16/15 = 1.0667 (SHOULD decrease speedometer by 6.67%)

Does this make sense? What have you sprocket changers (16 tooth to 15 tooth) noticed?

 

[Oscar54]

Hey Guys!

It is interesting reading everyones individual takes on the gearing issue.

To me 3 things are true about this debate:

1) Engine RPM and Drive Sprocket RPM Ratio for any gear remain unchanged regardless of whatever sprocket mod you do.

2) The Speedometer MPH to Engine RPM Ratio for any gear remain unchanged regardless of whatever sprocket mod you do.

3) Actual Speed MPH is determined only by the RPM of the rear wheel.

So if you want to definitively determine you MPH for a given engine RPM (not considering any error in the tach) you only have to calculate the rear wheel RPM for a given speed and work back through the gear ratio's for any particular gear to the corresponding engine RPM using your modified sprocket ratio. Then take your bike for ride and drive at those RPM's you calculated and log the speed registered on you speedometer. The difference is your error.

The diameter of your FZ6 rear wheel with a stock tire is 24.84". (I got this off the Dunlop website for the D252 tire) Therefore the circumference is 6.503112 ft. So your rear wheel must rotate 811.92 revolutions to travel one mile. So at 70 MPH in 6th gear with stock sprockets your RPM reading calculated is 5,766. My tachometer reading with stock sprockets at 70 MPH is 5,770. Pretty close.

The formula if you want to play with it is:

811.92 X No. of MPH / 60 = Wheel RPM.

Wheel RPM X Sprocket Ratio X Gear Ratio X 1.955 (Crank Shaft to Transmission Input Shaft Fixed Ratio) = Engine RPM

So do a matrix calculating Engine RPM for selected Speeds and Gears and your modified sprocket ratio then run your bike at those RPM's and Gears and see what you Speedo reads.:iconbeer:

BTW you can due this in your garage on the centerstand. Just chock the front wheel.

 

[fz6nick]

I was reading through this thread and thought it was funny how someone could think the engine is going to wear out faster from a higher rpm. It is going to be insignifigant it doesnt matter. Its kinda like saying if you normally shift at 8k rpm, shifting at 9k is going to wear your engine out faster. The FZ6is a sportbike. Its 600cc motor was designed to be in the 8k rpm plus range. Just like any other middleweight bike. Theres no way engineers would design the engine to let it get worn out faster at such insignifigant speeds. Its engineered to be ran very hard for very long period of times.

My dog was having a nightmare while I was writing this and i was laffing my a$$ off, so I hope w/e i just said makes sense. im to itred and lazy to read it over.

 

[FZ6Pilot]

Just checked mine 80mph indicates = 75mph GPS. This was "a rough estimate" because my gps indicates in tenths MPH. So the speedo shows 80MPH - could be anywhere from 74.5 to 75.5 on the gps (the speedo rounds to nearest whole #)

80/75 = 1.0667 (speedo reads 6.67% fast) If the speedometer is using a sensor on the output shaft, then changing the sprocket from a 16 to 15 tooth should give you a true speedometer reading.

16/15 = 1.0667 (SHOULD decrease speedometer by 6.67%)

Does this make sense? What have you sprocket changers (16 tooth to 15 tooth) noticed?

OOPS! The front sprocket should be changed to a 17 tooth (17/16 = 6.25%)
The Output shaft will turn slower (6.25% slower) to give the same roadspeed AND the speedo will report 6.25% slower making it pretty accurate.

Has anyone tried the 17 tooth?

 

[Oscar54]

My previous post was done late and I was tired.

You can also calculate your actual MPH for a given RPM using your new sprocket ratio.

Eng. RPM / 1.955 / 1.083 (for 6th gear, pull any gear ratio in here from the manual) / Mod Sprocket Ratio X 60 (to get to hours) / 811.92 (Rear Wheel Turns per mile) = MPH

I went + 1 on the front sprocket. So now when I'm at 5,770 RPM, my speedo still reads 70 MPH, but I am actually traveling at 74 MPH.

 

[Northern]

I have 15t front sprocket, and my speedohealer correction is -11.5%. It means, if my spedo shows 100, my real speed was 88,5 according GPS.

 

[OneTrack]

When I checked the accuracy of my 06 FZ6's speedo reading against my TomTom GO 720's speed reading, my FZ6 speedo showed 100 kph, while my GPS showed a reading of between 94 and 95 kph (it flickered back and forth).
My Subaru Outback's speedo, otoh, is spot on.

 

[dickieD]

I have 15t front sprocket, and my speedohealer correction is -11.5%. It means, if my spedo shows 100, my real speed was 88,5 according GPS.

i dont have a speedo healer.. but i was riding in twisties yesterday with all my mr2 buddies. and it is for 15t front sprocket... 11%.. so.. for me in the u.s. with a 08' .. thats what the difference is.. so just do the math.. if your doing 80.. your doing 72,..

 

[danieljfield]

Im looking for a -1 front and +2 rear kit. anyone know a place in the UK to order one from...ive found a place in US but its £160 all in to get it here?

 

[Guitar Man]

Just replaced my chain and sprockets (34,000 miles). I was -1 in the front and went back to stock. My gas mileage went from 40-41 mpg to 45-46 mpg. With the price of gas ever increasing I thought it would be good to go back stock. And that was with a 5.2% correction with a Speedo Healer. It was 11.1% with -1 in the front. Just some info for you.

 

[hk_fz6_05]

ok so my brain is way too frazzled to take in all the above math at the moment so let me just say thank you for throwing it up there.

And a question for the experienced folk: I'm currently running a stock setup (about to change since it's worn down) and have been experiencing inexplicably poor mileage no matter how hard or easy I run the bike.....it seems from reading the above, that there is a range of inaccuracy built into the speedos, (especially on older bikes?) - so, assuming that I might have been running with a slightly higher than average error (i.e. going slower than my speedo thought) would that affect my mileage negatively (or at least the fuel consumption calculated based on intake of gas and the odo)?
I.e. would the odo think I'd gone a shorter distance than in reality because the speedo thought I was going faster than in reality?

danieljfield - maybe try intobikes.co.uk - I just got an AFAM 15/46 530 setup from there and was very happy with them, though you still pay freight unless you spend quite a bit of money...