HarishK

Hi Follks,

I was a little kid when I first looked in to a Suzuki Samurai's Speedo, We kids used to discuss that this bike will do 140Kmph, while a Bajaj Scooter is capable of only 120Kays.

Later when I laid hands on Bikes I was totally fooled, it was a Herculean task for any 100CC bike to reach 100Kays on the speedo.

Lets not worry about the Speedo errors and accuracy.

But why do manufacturers calibrate the Speedometer to impossible heights?

I seriously don't know still why, 100-125CC bikes are calibrated upto 140Kays and 150CCs upto 160Kays, while a HH Karizma is up-to 200Kays

Which obviously is not possible for them achieve in stock form.
I did question the same to many Showroom/Service heads, their reply seems to just beat around the bush. (Like Company Standards etc)



Are we simply fooled by creating a supers-tic impression with Speedometer calibrations or any other Fact Hidden behind... need your thoughts guys!!!!

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Noor

Thread approved

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abhijeet080808

I agree with you here. IMO, a speedo should only display slightly more than the top speed achievable by the vehicle.

And, what is your thought on digital speedos that can be said to be calibrated for speeds up to '199' kmph?

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dr.cr

With error % most speedos have, they can't even be called Calibrated! Its right though about the wide Range, 140 on a bike which maxes ~85. joker made for downhills

pavanchirmade

Its like they want you to figure out how to take your bike to those speeds.

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Aneesh@4GHz

Room for more overclocking i guess.

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Samarth 619

A Ninja 250 and a Karizma both have 200kmph max reading, while the Ninja's reading is quite fair, Karimza's might seem overrated.

However, another thing to notice is that Karizma shows 5th gear's speed from 50 to 140 kmph using a curved line, which is true description. So, HH aren't disguising anything.


However, I summarize the following POSSIBLE reasons for high speeds on speedo's:


1. More room for modification and overgearing speed + downhill,

Stock Karizma touches 140 on speedo. For example, you get a Karizma Joel'led with everything he has, it might touch around 150 (on rev limiter in 5th), fine? You save more and more weight keeping it for the racetrack only.
Now you overgear using a 36/14 from P220 and it has very high overgearing now.

Plus you get a smaller profile front tyre that confuses the speedometer. Now, it might touch around 180-190 kmph on speedo. So, there is spare margin for such mods.


2. The company might make changes later on for more top speed. And use the SAME SPEEDO PARTS instead of new ones.

Example, Hero releases a brand new "Karizma Illegal Street Racing Edition", with 23 bhp, 6 speed & more top speed. (I know it won't happen, just suppose, ok? ) Then, they can use the same speedo which shows 200 kmph.


3. They want to fool the common man!! To heck with diplomacy!

jd666

The factors that i would like to list out are -

- The max speedo meter reading should be given keeping a margin beyond the top speed of the vehicle.

- Also the swinging of the arc of the speedo needle should be significant. ( as in it should be at a higher angle for a higher speed ). This creates a visual inference for the rider of his/her speed, and emphasizes on the speed they are travelling at ( possibly to knock some sense and get them to lower speeds ).

- Sometimes its just uniformity of design. ( equal arcs on the left and right of the centre of the meter )

- Another factor to be considered is vehicle speed at cut off rpm in top gear. So if the karizma hit say 125 in 5th, at around 7000 rpm, it can go till 140-150 till the engine hits cut off rpm in top gear. So that has to be factored in.

- Its a very vague and dumb argument ( which i have also seen people indulge in ), That the top speed of the vehicle is given by the max reading given on the speedo.

- Sometimes there are complete jumbles. For eg, the 1.3 esteem could do 165 in 4th, and the 5th gear was geared so tall, that if it was to hit rev limiter ( 6,600 rpm ) in 5th, the vehicle would be doing 265 kmph!!! But the speedo was calibrated till a sensible 220 kmph.

And the maruti 800 mpfi 5 speed could do a true 141 kmph!! but the speedo was calibrated only till 140 kmph. So the needle would actually swing past the 140 kmph mark for the top speed.

Mostly its just the aesthetics, and the impact of watching the needle hoist itself higher and higher for the thrill that impacts speedo meter design. Had my R15 have a small swinging rpm meter, it would not have been as much fun as watching the needle sweep across the dial with every gear and acceleration.

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My offerings to the gods of speed -

- KTM Duke 200
- Yamaha RXZ 5 speed

aargee

Read this - Speedometer - Wikipedia, the free encyclopedia
It has got much exhaustive answers as why the speedo is being calibrated

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HarishK

@ Aneesh@4GHz


Nope, I do not agree with this,

Even Manufacturers with Racing heritage like the Yamaha, Honda will not extend their warranty for Performance modds, even if they sell it themselves.

Upto my knowledge, particularly Indian manufacturers like HH, Bajaj (X TVS) are strictly against modds. So not sure if thats the reason for which the speedo is calibrated.

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