KawasakiTrax Community
General Category => General Discussion => Topic started by: mswyka on August 08, 2020, 06:14:35 AM
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I have, and perhaps continue to be, confused regarding Kawasaki speedometers and speedometer adaptors. Or I guess I should say that I have been confused for as long as I have known that there are 4 different speedometer adaptors - Left 3:1, Right 3:1, and Right 1:1.375.
COVID has given me more free time than usual so I started playing with the speedometers that we had lying around in the garage. With the help of a digital tachometer that my kids gave me i was able to simultaneously measure input RPM to the speedometer and the dial reading of the speedometer.
So what I found was that at about 450 RPM (direct) the speedometer reads 26 MPH, at 1,650 RPM - 95 MPH, and at 1,788 RPM - 105 MPH. Or a ratio of approximately 17.2 RPM/MPH. I can't be too much more accurate than that considering that the speedometer is analog.
This tells us that with a 3:1 reduction that at 26 MPH, the drive would be spinning 1,350 RPM and at 95 MPH the drive would spin 4950 RPM. Since 95 MPH is roughly 8,360 feet per minute this suggests that the OD of the drive would be 1.69 feet. With a 2.92 pitch and 7 lugs this comes out to just about 1.7 feet, so a pretty close correlation.
I have not spent any time with the newer speedometers with the 1:1.375 reduction. That will be for another day.
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I have run into the issue of having the wrong adapter on a drifter but have never done the math to figure out where the difference is. When I get a chance I will do some measuring.