Where can I find out info on how much a sprocket changes the speedo?

I need to take the info I find to court. I got two tickets with in two miles on my buddies 600 GSXR with a Vortex sprocket on it. Both where for 15miles over.

I already have a service ticket open on it at my job. The Service manager is going to write how much it was off by. I just need to find that info out. I also need to know the size of the sprocket that would make it 20mph off.


Thank You guys!

 

Im kinda confused.If you was caught going 15 over the limit,iif your speedo says you was going 20+ or 20 less that actual speed.You was still gunned 15 over.

 

No.. The ticket was wrote for 15 over. I want to tell the judge the sprocket made the speedo go over by 20. Making me travel well below the posted speed limit.

What size would make me travel 20 over? How many teeth. So I can then give him paperwork on how this would happen.

 

there was a 5 miles difference between me and my friends bike at about 45-50mph. i dont know if the speed you are going makes it more or less than that but im down 1 in the front w/ stock rear.

 

How fast were you going again? I can ride 90 mph and I am off by about 12 mph. My sprocket set up is +2 in the rear and -1 in the front. I'm sure it all depends on the bike too.

To be +20mph off you are probably gonna have to go with atleast a +10 rear sprocket if you were going 50-60 mph. Pretty much you were riding a stunt bike.

FYI Cesar only has -1 in the front

 

i think your fucked but the easiest way is to just put it on the dyno and see how far off the speedo is.

hell stock they are off atleast 5-10, throw in a gear, I'll guess i down 2 up which should put you almost 30mph faster than your really going.

45+15 =60 + that 30 your speedo is reading high.. so you were doing about 90 when clocked?


anyways, random guess, cause i'm bored today.

 

I know how he has his set up. I will present info for a sproket that would be that size.

Its not my bike I was riding. I dont know the size of the sproket he has. But my service manager looked over the bike and said he had ______ size sproket. This what happens to the speedo cuase of the sproket. *hand him paperwork*

 

so what your wanting to to tell the judge that the speedo was reading low because of a gear change?


some like +3 in the front but i'm pretty sure the guys at Sum of All Parts can give you the math.

 

Cool now we are getting somewhere. I emailed them.




So what it boils down too is I need to know the size of a sprocket that make your speedo read 20 under what your really doing!

 

It's going to be a percentage that the speedo is off, not a constant MPH. So I would recommend using a pace car at say 50mph or 70mph. Let them give you a thumbs up at a pre determined speed so you can see what the bike is doing. Turn the difference into a percentage and you'll be able to calculate any speed on the bike.

I hope this makes sence. It's easier to do then to explain. Bike speedo's are off anyway so a chart would have to be make/model and year specific.

If you need any help let me know.

Be sure to use a pace car not pace bike. Chances are that bikes speedo (although it may be stock) is off by as much as 14%.