does anyone know if doing the 520 chain conversion and going two up in the rear sprocket (leaving the front stock) or even going 1 up in the rear will affect my actual speedometer reading?
how much will it be off?
it adjusts the speedo for whatever percentage it's off from the actual speed. there are switches on the box that represent different percentage values. the directions tell you how to figure out the percentage of error, then you just flip the switches until they add up the percent that you are off and that's it. they come in different colors
Changing either sprocket will affect the speedo. The speedo is run off the countershaft sprocket, so think of it like riding a ten speed bike. When you're in tenth gear your peddling very slow, but moving fast. 1st gear peddling like crazy but hardly moving.
actually that's not quite accurate - if we were to draw that analogy, the tranny on the motorcycle would need to be between the front and rear sprockets, because that's where the gear ratios change on a bicycle.
since the countershaft sprocket is on the output shaft of the tranny, its rotational speed is directly proportional to the bike's forward speed. it won't spin faster and result in the bike moving slower, unless the chain is doing some serious jumping around on the sprockets.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by jbad: does anyone know if doing the 520 chain conversion and going two up in the rear sprocket (leaving the front stock) or even going 1 up in the rear will affect my actual speedometer reading?
how much will it be off?
I'm a little dozy tonight (no comments please!) but I can't see where you've mentioned what model you have. If your bike was made prior to SRAD days, you've got nothing to worry about, since you speedo is mechanical and works off the rotations of the front wheel. Otherwise (ie later models) you do have to pick up the 'yellow' box to correct the output.
Fat Bastard's bike: '93 GSXR1100wp CDN version w/ thoroughly ridiculous # of mods
I see what you're saying, maybe it wasn't the best description.
But changing sprockets will affect how fast the countershaft spins at a given speed.
Say you're going 60mph in 6th gear, and with stock gearing the motor is spinning @ 4000rpm. If you go down a tooth in the front (or up a couple in the rear), the drive sprocket will have to spin faster to turn the driven sprocket at the same speed.
also, on fuel injected suzukis, the ram air compensation is taken off the speed sensor signal - at higher speeds, the fi system injects a little more fuel. so if you drop the gearing significantly, the bike will run a tad richer, because the ecm thinks the bike is going faster than it actually is. but it's probably not a difference that you'd be able to feel.
the logical way for suzuki to do the ram air compensation would have been to use the map sensor, but for some reason, they didn't. according to the service manual the map sensor is only used in conjunction with engine speed only in light load situations to select the base fuel map. under higher loads, the throttle position sensor and engine speed are used to select the base fuel map, with other sensors used to determine if a little more or a little less fuel is required.
[This message has been edited by jeff (edited 02-09-2001).]