speedometer help

I went down 1 tooth on my front sprocket, about how much should this take away from my top end? Also, will this mess up my speedometer reading, for example speedo says 70, but I am actually going 55. The reason I am asking this is because while I was riding, I found an open spot, middle of nowhere, and got my speedo up to 174. this is a 2002 600 GSXR.

My 01 600 is stock, and i know the spedo is wrong too. does anyone know how off the stock ones are? I was on the highway today and it was saying I was doing 75-80, and I was just going with the flow of the traffic, so i know i was actually going slower. any help would probably help out a lof of guys. thanks

stock it is off, I think at 5-7% not sure though. Bink with sprocket change it will affect it alot more and you will be off maybe about 10-15 mph. Mount a gps to your bike that way it will always be correct or you can get a speddo healer.

gsxr 1000's usually read about 7-8% to high from the factory. You can buy a yellow box to re-caliberate your speedo. You will be off even more with the gear change. Best is to get a yellow box and caliberate it with a gps.

Ok Are You Going Faster Than Wht The Speedo Is Saying Or Slower?

You are actually going slower than what the speedo says...but it sure looks nice looking down at the high mph. haha

I am going slower, unless I have a majic 600 that really goes 174 :bounce

My Gixxer 600 Tops Out At Like 136 Mph That Is What The Dyno Reads, This Is After The Chain Kit