Wheel Diameter

REAP · May 18, 2009, 08:13:41 AM

Hey everyone

I have my KOSO gauge mounted up and all working fine except for the speed reading. Its way off: say im doing 60kms it will jump around like up to 360kmh then down to 20kmh then back up to 190kmh. It cant hold an accurate speed reading, so i sent an email to the ebay member who i bought it off and he said the outside diameter of the wheel with the tyre fitted could be off, It has to be perfect. Either that or the magnets where the speed is getting a reading are up-side down, but they dont have little "N's" on them to show which way round.

Anyway, what is the exact outside diameter of the front wheel with the tyre fitted on an 07 GS500?

tripleb · May 18, 2009, 09:14:14 AM

you have to mark your front tire and the ground and then walk out a full revolution and mark the ground again. then measure the distance between the 2 marks. It should be around 1797 mm.

bassmechanicsz · May 18, 2009, 09:31:44 AM

doesn't the outside diameter of the tire change depending on air pressure in the tire and from wear. When talking in mm i would think that these factors would have an effect on what you get for the diamter of the tire.

gsJack · May 18, 2009, 09:33:54 AM

There is nothing exact about tires.

tripleb · May 18, 2009, 10:49:13 AM

Quotedoesn't the outside diameter of the tire change depending on air pressure in the tire and from wear. When talking in mm i would think that these factors would have an effect on what you get for the diamter of the tire.

yes, you're right, but since you don't want to change it with the variable conditions on the tire (every ride) it's best to keep the tire in good shape which has other benefits as well. besides, it shouldn't change that much - a few millimeters won't change it more than a few mph at most.

REAP · May 18, 2009, 03:50:37 PM

Thanks guys

I have marked the ground and walked it out and got 1570mm? The front tire was pumped up to 36psi (pumped it up about 1 hour before), not that it makes a difference. Anyway, i think some of the magnets are around the wrong way so i'll change some of them around then take it for a spin with the old speedo beside it for comparison.

Thanks for the help

Roadstergal · May 18, 2009, 06:46:41 PM

An incorrect tire diameter entry will make it steadily read the wrong speed. If it's jumping around, that sounds like a ground problem.

REAP · May 18, 2009, 10:46:15 PM

Oh a ground problem, i like the sound of that. Thanks Road

Paulcet · May 19, 2009, 07:31:12 AM

Yeah, ground problem or the magnet-to-sensor distance is too great.

fred · May 19, 2009, 10:31:27 AM

Wait, you have a set of KOSO gauges on your GS? You really should post pictures of that as soon as possible. They've been discussed here before, but I've never seen a picture of them on a GS. I'm interested to see how you mounted them and how they fit with the rest of the bike.

tripleb · May 19, 2009, 10:40:55 AM

1570 mm can't be accurate. that's about 9 inches short from what I marked it at. you might want to check your math or your measurement again.

REAP · May 20, 2009, 04:11:11 AM

Oh ok, ill try around 1797 when the rain dies down. We are expecting to get around 400-500mm of rain in the next three days.

The KOSO supplier is sending me another gauge tomorrow for free, I dont even have to send him back the one I have on now. Its just to compare them just incase the one I have now is faulty. Now thats what I call trust

I will have pictures when I find my camera fred.

fred · May 20, 2009, 02:34:51 PM

Quote from: REAP on May 20, 2009, 04:11:11 AM
I will have pictures when I find my camera fred.

Cool. I'm very interested to see how they look.

dalsim · May 23, 2009, 05:28:14 AM

Quote from: REAP on May 20, 2009, 04:11:11 AM
Oh ok, ill try around 1797 when the rain dies down. We are expecting to get around 400-500mm of rain in the next three days.

The KOSO supplier is sending me another gauge tomorrow for free, I dont even have to send him back the one I have on now. Its just to compare them just incase the one I have now is faulty. Now thats what I call trust

I will have pictures when I find my camera fred.

I would love to see photos as well.

How's that rain going? It was quite windy here all day today and I'm about an hour westish from the gold coast. Had rain on and off all day but since Tuesday we've had about 270mm of rain. Saw footage on the news of the wind blowing through the coast and anything loose acting like ballistic missiles in the 60kt winds. Hope you did not get any damage with the weather.

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Wheel Diameter