Author Topic: 70mph in top gear??? (Read 8248 times)

the cueball · « **on:** 24 March 2015, 04:29:42 pm »

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!!

sinto · « **Reply #1 on:** 24 March 2015, 04:37:59 pm »

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

rhinoeli · « **Reply #2 on:** 24 March 2015, 04:44:45 pm »

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...

greenman · « **Reply #3 on:** 24 March 2015, 05:35:57 pm »

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

rhinoeli · « **Reply #4 on:** 24 March 2015, 05:41:15 pm »

Quote from: greenman on 24 March 2015, 05:35:57 pm

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

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

midden · « **Reply #5 on:** 24 March 2015, 07:35:37 pm »

Quote from: rhinoeli on 24 March 2015, 05:41:15 pm

Quote from: greenman on 24 March 2015, 05:35:57 pm
Mine sits around 61/2k at 70 with standard gearing.

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

mine is about the same

rhinoeli · « **Reply #6 on:** 24 March 2015, 08:02:18 pm »

Quote from: midden on 24 March 2015, 07:35:37 pm

mine is about the same

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

YamFazFan · « **Reply #7 on:** 24 March 2015, 08:12:48 pm »

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

the cueball · « **Reply #8 on:** 24 March 2015, 08:24:55 pm »

thanks all..

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

rhinoeli · « **Reply #9 on:** 24 March 2015, 08:49:38 pm »

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?

Millietant · « **Reply #10 on:** 24 March 2015, 08:56:19 pm »

Quote from: rhinoeli on 24 March 2015, 08:49:38 pm

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.

the cueball · « **Reply #11 on:** 24 March 2015, 08:58:15 pm »

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

Frosties · « **Reply #12 on:** 24 March 2015, 09:28:45 pm »

Quote from: Millietant on 24 March 2015, 08:56:19 pm

Quote from: rhinoeli on 24 March 2015, 08:49:38 pm
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.

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.

HarryHornby · « **Reply #13 on:** 25 March 2015, 06:41:36 am »

6000 revs for 70mph.

Punkstig · « **Reply #14 on:** 25 March 2015, 08:28:52 am »

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

midden · « **Reply #15 on:** 25 March 2015, 09:55:03 am »

Quote from: rhinoeli on 24 March 2015, 08:49:38 pm

What am I missing?

A few pounds perhaps.

[size=78%] You can't put a guaranteed standard on how hard an engine has to work. [/size]

rhinoeli · « **Reply #16 on:** 25 March 2015, 11:46:29 am »

Quote from: midden on 25 March 2015, 09:55:03 am

A few pounds perhaps. [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.

rhinoeli · « **Reply #17 on:** 25 March 2015, 12:14:37 pm »

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.

Paulfzs · « **Reply #18 on:** 25 March 2015, 12:32:46 pm »

got a phone?

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

rhinoeli · « **Reply #19 on:** 25 March 2015, 12:34:34 pm »

Quote from: Paulfzs on 25 March 2015, 12:32:46 pm

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.

Paulfzs · « **Reply #20 on:** 25 March 2015, 12:41:49 pm »

Quote from: rhinoeli on 25 March 2015, 12:34:34 pm

Quote from: Paulfzs on 25 March 2015, 12:32:46 pm
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.

most speedos read slightly wrong, id trust my phone gps over the speedo any day

rhinoeli · « **Reply #21 on:** 25 March 2015, 12:50:05 pm »

Of course GPS is way more precise.

What irritates my mind is the thing that many say their bike runs over 6000 rpm at 70 mph. Referring to the calculations above, 70 mph should be at around 5600 rpm. This is almost 10% difference. Tacho and speedometer should be more precise. In fact his speedo has to show less than the reality, which is not typical. Or the tacho has to show more than reality, which... yeah, we should test it with a proper rpm measuring device.

Might worth some experimenting on this topic in the future...

midden · « **Reply #22 on:** 25 March 2015, 01:08:09 pm »

Quote from: rhinoeli on 25 March 2015, 12:50:05 pm

Of course GPS is way more precise.

What irritates my mind is the thing that many say their bike runs over 6000 rpm at 70 mph. Referring to the calculations above, 70 mph should be at around 5600 rpm. This is almost 10% difference. Tacho and speedometer should be more precise. In fact his speedo has to show less than the reality, which is not typical. Or the tacho has to show more than reality, which... yeah, we should test it with a proper rpm measuring device.

Might worth some experimenting on this topic in the future...

I bet you're mates have fun winding you up

Quote from: rhinoeli on 25 March 2015, 11:46:29 am

Quote from: midden on 25 March 2015, 09:55:03 am
A few pounds perhaps. [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.

Basically I wasn't

rhinoeli · « **Reply #23 on:** 25 March 2015, 01:17:18 pm »

Quote from: midden on 25 March 2015, 01:08:09 pm

I bet you're mates have fun winding you up

Sorry, don't really know what does that mean. English is not my best...

Quote from: midden on 25 March 2015, 09:55:03 am

A few pounds perhaps. You can't put a guaranteed standard on how hard an engine has to work.

RPM, transmission, gear ratios and wheel speed are proportinal to each other. The only thing between them is the clutch. Don't know what else were you talking about.?

midden · « **Reply #24 on:** 25 March 2015, 01:50:41 pm »

Quote from: midden on 25 March 2015, 09:55:03 am

A few pounds perhaps. You can't put a guaranteed standard on how hard an engine has to work.

RPM, transmission, gear ratios and wheel speed are proportinal to each other. The only thing between them is the clutch. Don't know what else were you talking about.?
[/quote]
engine won't need to work as hard going down hill as it would going up hill for the bike to reach 70mph