Topic: Tachometer redlines

[Millie77]

Here's a general question about the redlines for CB tachometers which may apply to others as well:  Why is it that the redline area does not extend to the end of the RPM range on the tachometer?  For instance, my 1977 CB550K2 tachometer reads from 600 RPM to 12K RPM (the 12 is not marked), but the redline area is from 9300 RPM to 10300 RPM.  Once past 10300 RPM, the redline area reverts to the normal color of the dial.

[my name is nobody]

Not sure why, but suspect that engine won't rev any faster past the red zone anyhow. Maybe the numbers
extend past the zone for cosmetic effect(?)

[madmtnmotors]

Once you go past the red zone the face turns green again because if you spend very much time with the tach needle in this zone then green is what you are about to spend on repairs... 

[Stev-o]

Once you go past the red zone the face turns green again because if you spend very much time with the tach needle in this zone then green is what you are about to spend on repairs... 

HA!  Good explanation...

[slikwilli420]

Not sure why, but suspect that engine won't rev any faster past the red zone anyhow. Maybe the numbers
extend past the zone for cosmetic effect(?)

Have you ever ridden a 750? They will easily rev past that. They don't make any more power above that but will happily rev well past the suggested redline.

[madmtnmotors]

Not sure why, but suspect that engine won't rev any faster past the red zone anyhow. Maybe the numbers
extend past the zone for cosmetic effect(?)

They will easily rev past that. They don't make any more power above that but will happily rev well past the suggested redline.

+1

Mine has passed the red a couple of times, but only briefly, i.e. missed shift (false neutral) or else a late shift.

[PeWe]

Green area must be OK, right? Not slow down to red!
All CB tacho's I have seen have a green area beyond red.
I guess this is the bikes heaven, engine is supposed to have died earlier in the red part.

[TwoTired]

A wide red wedge is easier to take note of than a thin red line.  ...Particularly if you are paying proper attention to threats during driving.

Ever see a Honda owner's manual? ...never operate in the red area... Voids waranty.  ...meaning - you pay for repairs instead of Honda.  Not all bikes survive this operational area.

Cheers,

[FuZZie]

A wide red wedge is easier to take note of than a thin red line.  ...Particularly if you are paying proper attention to threats during driving.

Ever see a Honda owner's manual? ...never operate in the red area... Voids waranty.  ...meaning - you pay for repairs instead of Honda.  Not all bikes survive this operational area.

Cheers,

Yea but looks wise it's like "If I can just make 10300 everything will be fine"

[my name is nobody]

Not sure why, but suspect that engine won't rev any faster past the red zone anyhow. Maybe the numbers
extend past the zone for cosmetic effect(?)

Have you ever ridden a 750? They will easily rev past that. They don't make any more power above that but will happily rev well past the suggested redline.
[/quot


As a matter of fact, I have. To clarify, I own a k5. It's all stock, k5 cam and 18/48 sprockets and won't go past redline in 5th gear. So that is what I was referring to.

[TwoTired]

I think they should have made the area above the red, black with the notation, "this is just stupid" in neon lettering.

Same could be done for speedometers, I expect.   

Cheers,

[jlh3rd]

Any green area past the red line arc is known as ludicrous speed....so it’s a last resort area........🙄

[my name is nobody]

Some time back I saw some custom faceplates advertised on e bay. On the tach plate the word BANG
appeared after the red zone.

[Swoop]

It was a great question tho’.
I wonder how Honda would have explained it.

Steve

[FuZZie]

Some time back I saw some custom faceplates advertised on e bay. On the tach plate the word BANG
appeared after the red zone.

I like that lol!

[Jerry Rxman Griffin aka MuthaF'er]

The red line on mine is a warning to shift once the needle sees green again

[my name is nobody]

 Rod Serling sez it marks the entrance to "The Twilight Zone"

[jgger]

If you had the optional flux-capacitor that is where time travel starts. I thought everybody knew that. 

[scottly]

It was a great question tho’.
I wonder how Honda would have explained it.

Steve

It was a great question. Welcome Millie!
The beginning of the red zone is the maximum safe Continuous RPM, and the end of the red zone is the maximum safe Momentary RPM.   

[Gordon]

The Honda engineers figured if you weren't paying attention through that whole part of the "don't go here" red area, then you probably weren't listening to them anyway, so they may as well shut up and use their talents elsewhere.   

[Deltarider]

When you've reached the end of redzone, blood will come out of your eyes and things in front of you will be red anyway. Jerry Rexman and Gordon came close.
Millie, it's a very intelligent question. You're from Maine. I always wanted to know: is there really a location called Crabapple Cove?

[dave500]

too bad these tachos wernt "tell tale' types?I doubt many new owners broke these bikes in,they were built to handle high rpms right from the start,if your into the red and not top gear your missing out on torque.

[jlh3rd]

Gotta disagree with that

It was a great question tho’.
I wonder how Honda would have explained it.

Steve

It was a great question. Welcome Millie!
The beginning of the red zone is the maximum safe Continuous RPM, and the end of the red zone is the maximum safe Momentary RPM.   

[jlh3rd]

Gotta disagree with this one also

too bad these tachos wernt "tell tale' types?I doubt many new owners broke these bikes in,they were built to handle high rpms right from the start,if your into the red and not top gear your missing out on torque.

[dave500]

oops!when I first got a 550 rebored I rode it as per normal for about an hour,changed the oil and filter then just still ride the #$%* out of it,you can be too carefull and glaze or smooth the hone over,just do an early oil change then flog em,these have a quite low piston speed despite the rpm,never lug a new motor let it spin free.