new skins and speedo problems

[DumbLuck]

Hey ya,
I put a set of Metzler Z6's on my '90 750 Kat. of course the fitment chart was wrong and i have a 110/70 17 front at the moment. would that i knew about Cyber's tire information before getting skins. hopefully my dealer will work it out between Metzler, them, and me and i'll get the 120/70ZR17 58W it should have up front. In the meantime, and after the skin is replaced, my speedo is grossly off. will the speedo puck from a post '98 600/750 Kat fit on a pre '98 Kat 750 front rim as a simple cure? I see that the post '98 kats came with 120/70Z17's up front, or is the '98 already into the electronic speedos instead of mechanical? i know the speedo will be closer with the new 120/70 vs the new 110/70 but i still dont want to guess how fast i'm goin.

[seabass10369]

98+ is electric speedo on the output shaft... thats what i know

[The CyberPoet]

Pre-98 measures speed off the front wheel via a gear-driven cable.

The difference at the speedo between a 110/80 (original fitment) and a 120/70 (my recommended replacement based on current tire technologies) is minimal (something like 1.5 mph at 60 mph), and far less of a factor than the factory deviation already built into the bike's speedo. A 110/70 probably adds another 1 to 2 mph deviation, but I wouldn't worry about the differences in general.

Cheers,
=-= The CyberPoet

[DumbLuck]

Pre-98 measures speed off the front wheel via a gear-driven cable.

The difference at the speedo between a 110/80 (original fitment) and a 120/70 (my recommended replacement based on current tire technologies) is minimal (something like 1.5 mph at 60 mph), and far less of a factor than the factory deviation already built into the bike's speedo. A 110/70 probably adds another 1 to 2 mph deviation, but I wouldn't worry about the differences in general.

Cheers,
=-= The CyberPoet

thanks Cyber,
here's the math
110/80 = 88mm
120/80 = 84mm (prolly close enough)
110/70 = 77mm which translates into roughly 54mph when the speedo shows 60 that's about 1 mph slow for every 10 (measured using the electronic speed limit sign on the east side of Hastings, MN on cty 46/47)

is there a different inner gear available? i have a severe dislike of 2 wheelers runnin up my butt

btw, Metzler is bein a putz about swappin out the skin

[The CyberPoet]

If you know what the speedo difference is, just drive 66

No regearing solution that I know of for mechanically driven speedo's. The common cheap-fix answer is to put a hall sensor at the rear, drill a hole & mount a magnet in the rear rotor and "sense it", then push that output through an electronic bicycle speedo at the dash. Such bicycle kits are available for well under $100 (possibly even under $30 -- but I haven't priced on in years).

Cheers,
=-= The CyberPoet