155mph speed limiter question

[Mr Tidy]

A lot of bikes with digital speedos stop at 186mph even though it will still pull past this.
Im sure 186mph is 299kph

Many years ago I bought a Yamaha XJ550 that was an import from the US - the speedo stopped at 80 mph!

But shortly afterwards I managed to buy a UK model with a knackered engine so got a speedo with 3 figure numbers on it, and might have needed them (on a private road obviously). :lol:

My MC seems to be geared for at least 170mph in 5th - maybe one day I'll find out!

 

[Pondrew]

My MC seems to be geared for at least 170mph in 5th - maybe one day I'll find out!

There are very complicated physics that come into play. Aerodynamics become the predominant player over about 130mph IIRC. Over a certain speed the drag is exponentially superior to the power. Not that any of this matters, as I am far too old to travel above 60mph anyway

 

[Pondrew]

Nah, keep the limiter & invent your own hypothetical top speed. Who's gonna prove you wrong down the pub anyway? My remapped N20 is good for n+5mph (where n is the professed top speed of my mates car

Yeah like the thinking. Out of interest; why n? Why not X?

As a sideline; I have a (V8 AA) Ford which is limited to 155mph aswell. I thought it was just zee Germans; the septics are at it too.

 

[buzyg]

A lot of bikes with digital speedos stop at 186mph even though it will still pull past this.
Im sure 186mph is 299kph

Many years ago I bought a Yamaha XJ550 that was an import from the US - the speedo stopped at 80 mph!

But shortly afterwards I managed to buy a UK model with a knackered engine so got a speedo with 3 figure numbers on it, and might have needed them (on a private road obviously). :lol:

My MC seems to be geared for at least 170mph in 5th - maybe one day I'll find out!

Indeed the ///MR will do approx 171 mph and there is no limiter on 5th, that I know of. Not bad for a aging hair salon. Been talked to death over the years on here.

 

[ph001]

There are very complicated physics that come into play. Aerodynamics become the predominant player over about 130mph IIRC. Over a certain speed the drag is exponentially superior to the power.

Aerodynamic drag is the dominant factor at much lower speeds then 130mph. In simple terms, drag is proportional to the square of the speed (Drag ∝ v2). So basically if you want to go twice as fast you have to work four times harder. e.g. if it takes 10bhp to go 30mph, it takes 40bhp to go 60mph and 160bhp to get to 120mph. This does ignore the drag coefficient of the tyres and the running gear.

 

[buzyg]

A good thread here..

https://z4-forum.com/forum/viewtopic.php?f=2&t=6572&hilit=top+speed

Looking forward to reading the first proper report on what top speed a modified M40i has. Surely faster than the older models, but not seen any facts to support that assumption yet. Could also be that it is not stable enough to go much faster. As is certainly the case in the ///MR, where the front end starts to go light above 160mph.