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70mph in top gear??? - Printable Version

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+--- Thread: 70mph in top gear??? (/showthread.php?tid=71940)

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70mph in top gear??? - the cueball - 24-03-15

since my speedo is still goosed, can someone please tell me what revs the bike sits at in 6th gear at 70mph please....


I've got the others figured out (30/40/50/60) so its the only one I don't know!


many thanks!!


:o

Re: 70mph in top gear??? - sinto607276 - 24-03-15

I'd need to slow down tomorrow and take a note for you B-)

Re: 70mph in top gear??? - rhinoeli - 24-03-15

6th gear with original sprocket ratio is very easy in km/h

50 km/h -> 2500 rpm
100 km/h -> 5000 rpm

70 mph = 112 km/h -> 5600 rpm

Hey, if you figured out 30 mph, you can do math to get revs for 70 mph...

Re: 70mph in top gear??? - greenman - 24-03-15

Mine sits around 61/2k at 70 with standard gearing.

Re: 70mph in top gear??? - rhinoeli - 24-03-15

(24-03-15, 06:35 PM)greenman link Wrote: Mine sits around 61/2k at 70 with standard gearing.


Are you sure it is standard gearing? It seems to be -1 front sprocket.

Re: 70mph in top gear??? - midden - 24-03-15

(24-03-15, 06:41 PM)rhinoeli link Wrote: [quote author=greenman link=topic=16362.msg188340#msg188340 date=1427218557]
Mine sits around 61/2k at 70 with standard gearing.


Are you sure it is standard gearing? It seems to be -1 front sprocket.
[/quote]
mine is about the same

Re: 70mph in top gear??? - rhinoeli - 24-03-15

(24-03-15, 08:35 PM)midden link Wrote: mine is about the same


70 mph at 6200 rpm in 6th gear? That is certainly not the stock sprocket ratio...

Re: 70mph in top gear??? - YamFazFan - 24-03-15

My 600 is as standard as they come & top gear at 70mph is a fraction over 6000rpm. Maybe 6100'ish.

Re: 70mph in top gear??? - the cueball - 24-03-15

thanks all..


I had a feeling it was about 6 - 7k ish... give or take...  :rollin

Re: 70mph in top gear??? - rhinoeli - 24-03-15

What the heck... Ok, seems everyones FZS600 except mine runs over 6000rpm at 70mph in 6th gear.

Mine is a metric instrument model with standard (15/48) sprockets.

It shows:
100 km/h -> 5000 rpm
112 km/h (70 mph) -> 5600 rpm

gearingcommander.com confirms these numbers.

What am I missing?

Re: 70mph in top gear??? - Millietant - 24-03-15

(24-03-15, 09:49 PM)rhinoeli link Wrote: What the heck... Ok, seems everyones FZS600 except mine runs over 6000rpm at 70mph in 6th gear.

Mine is a metric instrument model with standard (15/48) sprockets.

It shows:
100 km/h -> 5000 rpm
112 km/h (70 mph) -> 5600 rpm

gearingcommander.com confirms these numbers.

What am I missing?
Don't think you're missing much - our is also on standard sprockets and gearing and 70 comes up under 6,000 as well.

Don't know what s going on but it looks like we have sprocket changing ghost hanging around.


Re: 70mph in top gear??? - the cueball - 24-03-15

so I could have a few speeding tickets coming in the post then?!?!


:'( :'(


:eek

Re: 70mph in top gear??? - Frosties - 24-03-15

(24-03-15, 09:56 PM)Millietant link Wrote: [quote author=rhinoeli link=topic=16362.msg188375#msg188375 date=1427230178]
What the heck... Ok, seems everyones FZS600 except mine runs over 6000rpm at 70mph in 6th gear.

Mine is a metric instrument model with standard (15/48) sprockets.

It shows:
100 km/h -> 5000 rpm
112 km/h (70 mph) -> 5600 rpm

gearingcommander.com confirms these numbers.

What am I missing?
Don't think you're missing much - our is also on standard sprockets and gearing and 70 comes up under 6,000 as well.

Don't know what s going on but it looks like we have sprocket changing ghost hanging around.
[/quote]


Mine sits just under the 6k at a SatNav indicated 70mph. My speedo went last year so had to use a Tom Tom for speed for a couple of weeks.

Re: 70mph in top gear??? - HarryHornby - 25-03-15

6000 revs for 70mph.

Re: 70mph in top gear??? - Punkstig - 25-03-15

Speedo runs fast after 50mph so although the maths may be correct people will have slightly different figures to what the instruments tell them!

Re: 70mph in top gear??? - midden - 25-03-15

(24-03-15, 09:49 PM)rhinoeli link Wrote: What am I missing?
A few pounds perhaps.  Wink [size=78%]  You can't put a guaranteed standard on how hard an engine has to work. [/size]

Re: 70mph in top gear??? - rhinoeli - 25-03-15

(25-03-15, 10:55 AM)midden link Wrote: A few pounds perhaps.  Wink [size=78%]  You can't put a guaranteed standard on how hard an engine has to work. [/size]
Basically you are talking about the cluth slipping which may count at hard accelerations or much higher speeds and rpms. Don't think it is the case here.

Re: 70mph in top gear??? - rhinoeli - 25-03-15

Ok folks, let me do some maths to clear things up. I am using values from the specifications found in the official service manual.

Primary reduction ratio is 82/48 (1.708).
Gear ratio in 6th gear is 29/27 (1.074).
Secondary reduction ratio with standard sprockets is 48/15 (3.200).
Diameter of the rear wheel is around 600 mm (depending on tire type, pressure, rotation speed etc), so circumference at 100 km/h must be around 1900 mm.

Let's assume 5000 rpm.
5000 / 1.708 / 1.074 / 3.2 = 852 rpm = 51120 wheel rotations per hour
51120 rotations per hour * 1900 mm = 97 km/h

So we can roughly calculate 6th gear speed/rpm ratios with the following:
50 rpm -> 1 km/h
80 rpm -> 1 mph (5600 rpm -> 70 mph)

My Fazer's instruments confirm these numbers. Also gearingcommander.com gives almost the same results.

Re: 70mph in top gear??? - Paulfzs - 25-03-15

got a phone?


attach it to the bike so you can see it and install a speedo app

Re: 70mph in top gear??? - rhinoeli - 25-03-15

(25-03-15, 01:32 PM)Paulfzs link Wrote: got a phone? attach it to the bike so you can see it and install a speedo app


Done that. My speedo cheats around 3-4% up.