Top gear engine speeds GS500 v FZ6 v CB400

[Wombat1940]

when I read the title of this thread I thought you meant top speed that the gear ratio's would allow.by this for example(don't try this at home)" i'm a professional idiot!"I put my bike on the center stand (had my brother help me to stabilize the bike if we were to incur extreme vibration's),started it up put it 6th gear gently let the clutch out to see if this was going to go smoothly,was pleasently suprized at just how well balanced it was;then began to roll the throttle to wide open posistion........it bumped the rev limiter at 166mph.......mission acomplished everthing went very well......YES I KNOW I'M AN IDIOT!!!!!!

No you'r not ..... your doing research and developement

Seriously it always very hard to give a title to a thread that accurately points to the issue.

I hate this type "I'm a winner" or "Please help me" or "What does this mean?". I never look. At least I got you to have a look ....... :rockon: All the best and ride carefully.

 

[The Toecutter]

Yea! R&D,that sound,s alot better!! LOL.....well since you don't think i'm crazy i'll give you some more #'s I got through R&D!....first I weigh 215lbs my bike in full stock form 2,500 miles on the clock with an outside temp of about 85degrees had a top speed of 141mph in 5th gear around 12,500 rpm.I had about a mile to reach this "plateau" it felt like I was really fighting the wind past 135mph.this was last summer since then i've added the lower fairing and modified my airbox.

 

[eric76]

I am currently trading in my GS500 for a FZ6.

I love the sound/feel on the GS500 at 5000rpm sitting on 100kph. Its almost like cruising in over-drive.

My brother has a CB400. At 100kph he's looking for another gear.

I did some calculations to compare the GS v the CB v the FZ6 engine speeds at 100kph each in top gear. You'll find it here:

drop.io wombat1940

or, very briefly

GS500: Engine speed 5000rpm ...................... 100kph
CB400: Engine speed 5396rpm ...................... 100kph
FZ6S: Engine speed 6379rpm ...................... 100mph

This just a summary of the result. Figures used to determine the outcomes can be provided by email upon request.

I'd love comments as to whether I've got it right.

I am not sure how you got all these figures, but i rode a CB400 before and at 100KPH top gear, i remember very clearly rpm should be ard 6300 to 6400 on stock sprocket and rim....why i can remember this is that CB400 vtec valve opens at 6350rpm and at this spot i can feel the power kicks in.....:rockon:

 

[Wombat1940]

Yea! R&D,that sound,s alot better!! LOL.....well since you don't think i'm crazy i'll give you some more #'s I got through R&D!....first I weigh 215lbs my bike in full stock form 2,500 miles on the clock with an outside temp of about 85degrees had a top speed of 141mph in 5th gear around 12,500 rpm.I had about a mile to reach this "plateau" it felt like I was really fighting the wind past 135mph.this was last summer since then i've added the lower fairing and modified my airbox.

That makes you about 15+ stone. Let say with not disrespect a fare lump of a lad. I'm about 13.5 in my jocks.The 141mph is interesting and equates to 5300rpm and 60mph in 5th. This should give 4800rpm if you changed to 6th. This matches my theoretical figures (4600rpm) for 60mph (100kph).

Likewise if you changed to 6th at 141mph you would be doing 11400rpm.

Did you drop it to top? If so, knowing it as a high end torque motor and assuming wind resistance was manageable you should, in theory, be able to accelerate passed the 141mph in top. Although 141mph (225kph) is quick, and in 5th.

 

[Gilo-FZ6]

im 6' 7"-8" ish and weigh 19 stone but if i did do these sort of speeds,i may be able to confirm that is possible even with my bulky frame

 

[Wombat1940]

im 6' 7"-8" ish and weigh 19 stone but if i did do these sort of speeds,i may be able to confirm that is possible even with my bulky frame

No ....... don't think any of us should do that. Lets leave its "in theory only". its just that sheveport1 got to 141mph in 5th. Did he ever change to 6th?

 

[SANGER_A2]

It's not very scientific, but mine does 6500 rpms at 70mph and I weigh very little. The wind-blast on my helmet is pretty damn strong at that speed with the Puig double-bubble. I'm thinking about getting some screen trim and sacrificing noise levels.

 

[The Toecutter]

No ....... don't think any of us should do that. Lets leave its "in theory only". its just that sheveport1 got to 141mph in 5th. Did he ever change to 6th?

No i didn't get to 6th gear.I ran out of clear roadway on the deselete strip of four lane I was on.also the bike didnt feel like it was going to give me much more speed anyway.this is what promted me to start searching for a way to add Ram air plumbing to the air box.which turned out to be futile without major mod's to the frame or gas tank.i'm 6'1" 15 stone I beleive in your weight system.I was tucked down below the windsheild legs against the tank.it acelerated very quickly to the 130mph then noticeibly slower to the 141.I was fighting wind resistance more than the weight in my conclusion.for example i've riden many fully faired bikes with similar power and reached much higher top speed's alot quicker.our fz is considered a street fighter because it's more of a fast sprinter than a top speed machine.

 

[dako81]

This is calculating engine RPM at 70mph, actual 70mph, not what the speedo reads at 70mph which has been reported to be up to 6-7% off stock by some. (However the odo has been reported to be spot on, the speedo is purposely set to read fast due to import laws)

Primary reduction ratio - 86/44 (1.955)
Secondary reduction ratio - 46/16 (2.875)
Gear ratio, 1st gear - 37/13 (2.846)
Gear ratio, 2nd gear - 37/19 (1.947)
Gear ratio, 3rd gear - 28/18 (1.556)
Gear ratio, 4th gear - 32/24 (1.333)
Gear ratio, 5th gear - 25/21 (1.190)
Gear ratio, 6th gear - 26/24 (1.083)

180/55R17 Tire = 24.795" tall
24.795" tall x pi = 77.895" circumference
63,360" inches per mile / 77.895" circumference = 813.40 revolutions per mile and 813.40 revolutions per minute at 60 miles per hour.

70mph = 4,435,200" per hour / 60 minutes per hour = 73,920" per minute
73,920" per minute for 70mph / 77.895" circumference = 948.97 rpm at 70 for the rear wheel

Working from the rear wheel to the crankshaft in, all at 70 true mph at the rear wheel:

6th gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.083 (6th gear (26/24)) x 1.955 (primary reduction ratio (86/44)) = 5776.51rpm at crank

5th gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.190 (5th gear (25/21)) x 1.955 (primary reduction ratio (86/44)) = 6347.23 rpm at crank

4th gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.333 (4th gear (32/24)) x 1.955 (primary reduction ratio (86/44)) = 7109.96 rpm at crank

3rd gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.556 (3rd gear (28/18)) x 1.955 (primary reduction ratio (86/44)) = 8299.39 rpm at crank

2nd gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.947 (2nd gear (37/19)) x 1.955 (primary reduction ratio (86/44)) = 10384.92 rpm at crank

1st gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 2.846 (1st gear (37/13)) x 1.955 (primary reduction ratio (86/44)) = 15180.01 rpm at crank (Not possible on FZ6)

To find rpm at a different speed, just take the ratio of the speed you want over 60, and multiply it by 813.40 revolutions per minute. So for example 145mph, 145/60 = 2.4166 x 813.40 = 1965.72 rpm at rear tire at 145mph. Then plug this into one of the above in place of the 948.97.

So for 5th gear @ 145mph:
1965.72 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.190 (5th gear (25/21)) x 1.955 (primary reduction ratio (86/44)) = 13147.80 rpm at crank

So since the speedo is off by a %, if someone hypothetically is "going" 145 in 5th by the speedo, and they're exactly at 12,000rpm on the tach, they're actually going 132.34mph if the rear tire is not wore down. This would make the speedo happy roughly 9%.

Also, there is evidence the tach is happy by a percentage as well, as described by Hellgate in his post about his cutom dyno tuned map he had done for his FZ when he had it:

.......

A few side notes, 1) our TRUE redline is 13,600, NOT 14,000. Like our speedos the tach is high. The PC3 gives true reading, the Yamaha reading, 14K, is for sales purposes only. ...

So, this is about 3% happy on the tach. I don't feel like calculating all of this into the equation, but you get the general idea.


Is this discussion over yet? :spank:

Also, please correct me if I am wrong. I would appreciate it!

 

[Wombat1940]

This is calculating engine RPM at 70mph, actual 70mph, not what the speedo reads at 70mph which has been reported to be up to 6-7% off stock by some. (However the odo has been reported to be spot on, the speedo is purposely set to read fast due to import laws)

Primary reduction ratio - 86/44 (1.955)
Secondary reduction ratio - 46/16 (2.875)
Gear ratio, 1st gear - 37/13 (2.846)
Gear ratio, 2nd gear - 37/19 (1.947)
Gear ratio, 3rd gear - 28/18 (1.556)
Gear ratio, 4th gear - 32/24 (1.333)
Gear ratio, 5th gear - 25/21 (1.190)
Gear ratio, 6th gear - 26/24 (1.083)

180/55R17 Tire = 24.795" tall
24.795" tall x pi = 77.895" circumference
63,360" inches per mile / 77.895" circumference = 813.40 revolutions per mile and 813.40 revolutions per minute at 60 miles per hour.

70mph = 4,435,200" per hour / 60 minutes per hour = 73,920" per minute
73,920" per minute for 70mph / 77.895" circumference = 948.97 rpm at 70 for the rear wheel

Working from the rear wheel to the crankshaft in, all at 70 true mph at the rear wheel:

6th gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.083 (6th gear (26/24)) x 1.955 (primary reduction ratio (86/44)) = 5776.51rpm at crank

5th gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.190 (5th gear (25/21)) x 1.955 (primary reduction ratio (86/44)) = 6347.23 rpm at crank

4th gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.333 (4th gear (32/24)) x 1.955 (primary reduction ratio (86/44)) = 7109.96 rpm at crank

3rd gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.556 (3rd gear (28/18)) x 1.955 (primary reduction ratio (86/44)) = 8299.39 rpm at crank

2nd gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.947 (2nd gear (37/19)) x 1.955 (primary reduction ratio (86/44)) = 10384.92 rpm at crank

1st gear:
948.97 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 2.846 (1st gear (37/13)) x 1.955 (primary reduction ratio (86/44)) = 15180.01 rpm at crank (Not possible on FZ6)

To find rpm at a different speed, just take the ratio of the speed you want over 60, and multiply it by 813.40 revolutions per minute. So for example 145mph, 145/60 = 2.4166 x 813.40 = 1965.72 rpm at rear tire at 145mph. Then plug this into one of the above in place of the 948.97.

So for 5th gear @ 145mph:
1965.72 rpm (at rear wheel) x 2.875 (secondary gear reduction (46/16)) x 1.190 (5th gear (25/21)) x 1.955 (primary reduction ratio (86/44)) = 13147.80 rpm at crank

So since the speedo is off by a %, if someone hypothetically is "going" 145 in 5th by the speedo, and they're exactly at 12,000rpm on the tach, they're actually going 132.34mph if the rear tire is not wore down. This would make the speedo happy roughly 9%.

Also, there is evidence the tach is happy by a percentage as well, as described by Hellgate in his post about his cutom dyno tuned map he had done for his FZ when he had it:



So, this is about 3% happy on the tach. I don't feel like calculating all of this into the equation, but you get the general idea.


Is this discussion over yet? :spank:

Also, please correct me if I am wrong. I would appreciate it!

...........

 

[Gilo-FZ6]

My FZ6 does 100mph at 14000RPM.

In second gear. :rockon:

Fred

in the name of science i checked mine not more that 10mins ago..mine does 94mph in 2nd on the limiter in a strong headwind

 

[Wombat1940]

I've now been through all your figures and in principal we have come to the same conclusion but working from different starting points (ie. you the back wheel me the engine). HOWEVER my values for the back wheel dimensions made my calculations considerably skewed. My back wheel O/A dia was approx 21 inch as against your's of 25 inch, which as you would appreciate changes the rpm of the back wheel considerable to match the linear speed of the bike. I was also using a relationship between the linear speed of the GS (60mph) and the relative speed of the crank (5000rpm). This was also a ballpark figure and not directly related, as to using straight specification of the FZ6. I'm going to redo the spreadsheet with the (your) revised rear wheel speed(s) and recalculate for the GS, FX and CB. Stay tuned ..........
By the by how did you arrive at 24.98in for the outside dia of the rear tyre? Measure it? Mine was [rim dia (17in)] plus [tyre depth (55mm), twice]

 

[Wombat1940]

in the name of science i checked mine not more that 10mins ago..mine does 94mph in 2nd on the limiter in a strong headwind

IMHO and with no disrespect its the 94mph in 2nd gear at 14000 rpm the bit I need. The headwind is a power (kinetics) issue. Not, as I need, a speed (kinamatics) issue.
Thanks for the figures.