how fast??

[gsxr600nick]

hi i have changed my wheels on my kmx 200, the front now has a 18 on it where as it was a 21 standard.

can anyone tell me does this alter the speedo reading???? if so can you get some kind of conveter?

cheers for any help
nick

[RichLockyer]

If the overall diameter of the tire changed, then the speedometer changed as well.

What size are you running now, and what size were you running before?

[gsxr600nick]

not sure of the exact diameter change but the wheel fitted at mo is a fair bit smaller

[RichLockyer]

Draw a chalk line on the floor and on each tire.
Line up the chalk lines and roll each tire once, then measure how far they rolled from the first chalk line.

Divide the two numbers... little number divided by the big number, then subtract 1, and that's your correction percentage.

Fair bit smaller? Unless you are able to slide the forks WAY down in the triple clamps, or lower the rear suspension to put the bike at the same "level" it was at before, that's going to hurt your high speed stability.
Be very careful the first time you open it up in top gear... could be asking for a tank slapper.

[gsxr600nick]

thanks for the advice i will work out the diameters as soon a s we get a nice day.

can you get adaptors to give correct speedo readings?

[RichLockyer]

Originally Posted by gsxr600nick

thanks for the advice i will work out the diameters as soon a s we get a nice day.

can you get adaptors to give correct speedo readings?

Not for a cable-driven speedo. You'll just have to do the math mentally, and realize that your odometer is going to be fast by the same percentage, so if say you're 20% off (which is a real possibility), that means that when your odometer shows 600 miles and you're thinking about an oil change, you really only have 480 miles on the bike.
Same for fuel economy... don't go telling people you're getting 60mpg.