RPMs v/s MPH ?

[skotty]

Was just curious, would anything change the rpms v/s the mph by doing mods(excluding sprocket ratio changes) on the bike? I know sprocket ratio change adversely affects the rpms v/s mph.

On my 750, in 6th gear, at 6000 rpm, it makes around 82 mph. Was wondering if its standard for all 750s/600s or does that change with mods?

[TheKlic]

Well, technically if you don't change the ratio nothing will change it, but it if your engine is making more power because of other mods it will be easier to push against the wind and be less gas at those RPMs, I think.
I know I put my cruise control on one day and sat up, then laid down, my rpms went up and my speed went up by about 400rpm or around 5mph whenever I laid down

[Court93kat]

The only mod I can think of that would affect your rpms vs mph besides a sprocket change would be a tire change. If you go with a shorter tire it would be kind of like a sprocket change, just much less dramatic. Of course that is referring to the rear tire only.

[Wade-Kat600]

yup - its all about the distance the tire/sprocket travels - bigger tire is more distance at higher rpm - opposite concept with sprocket - smaller rear = more tire travel compared to sprocket travel - larger front sproket is more sprocket travel compared to shaft rotation.

Very simple concept.

[The CyberPoet]

On your model, the speedo reading is taken at the output shaft of the transmission (effectively at the front sprocket shaft for the chain). Anything from there back (pretty much all of them have already been listed) will change the relationship between RPM's and MPH.

There is one other thing that will affect the ratio, and that's a slipping clutch -- where the RPM's will spin up without a direct correlation to the increase in speed (i.e. - it will take a while for the speed to catch back up to the RPM's).

If you do go for an alternative set-up in terms of sprockets/tire sizes/wheel sizes/etc, there are two products that I know of which will allow you to set a correction factor to recalibrate the speedo: yellowbox and speedo healer. Both are available on the web.

Cheers,
=-= The CyberPoet

[Wade-Kat600]

good point - didnt think about the front tire

clutch maybe a stretch - i'd expect someone would notice clutch slippage

[skotty]

Thanks for the input guys.