Early Supersport/Monster 17mm/20mm axle wheel swap.

[koko64]

A customer has purchsed a 1992 Mk1 Superlight with the magnesium Marvic composite wheels. Early 17mm axle front wheels are getting thin on the ground but the 20mm axle wheels are common. A set of 1995 M900 wheels were purchased to retire the 30 year old corroded Marvics for show purposes only. The roads are rough around here. The rear wheel is no issue, a straight fit, but we are hoping to retain the 17mm front axel and speedo drive with the Monster rim. Has anyone successfully used the 20mm axle front wheel with a bearing and spacer change to mate with the smaller axle and Speedo drive. Is any machining required? Does the early spacer transfer across?

The other possible way to do it would be to find a 20mm axle, 20mm Speedo drive and 20mm fork insert for the axle thread.

I have conflicting advice as to how difficult this task is. I have looked at the issue via the search function and on line generally. The wheel or axle may require machining or a custom bearing spacer fabricated.

Cheers.

[koko64]

Update.

Looking through dusty old boxes of parts in my shed I found a 20mm Monster axle and lhs fork insert. They fit the forks and wheel. I am hopeful that if we can find a 20mm axle Supersport speedo drive then it should all bolt up fine. According to my measurements it will be plug n play. Just one thing, how much out will the speedo be with the larger diameter speedo drive? The earlier speedo drive is substantially smaller in outer diameter with the worm drive ring. Do we then buy a later speedo or can our trusty speedo repair guy recalibrate the original unit?

[ducpainter]

I don't think the diameter of the drive will be the issue. If the fear ratios in the drive are different, that will be an issue, as well as tire size. IIRC, some of the older SS bikes came fitted with a 120/60 tire which had a smaller section which affects circumference.

You're going to have to bolt it up and see.

[koko64]

I'm hopeful.

[koko64]

Good news is that the part number is the same for every year 900SS Veglia speedo from 91-97. That supports what you said about only the gear ratio changing in the speedo drive. Thats great news. So now to find one..

[ducpainter]

https://www.ebay.com/itm/194885155533?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=194885155533&targetid=1645685074528&device=c&mktype=&googleloc=9002329&poi=&campaignid=16730423415&mkgroupid=135815925780&rlsatarget=pla-1645685074528&abcId=9300841&merchantid=6296724&gclid=CjwKCAjw14uVBhBEEiwAaufYx261Vo2MImxtaI-ecn5NU6oEtgMcWuHwN0Mc69zTz42Bo638xqyoJhoCXKwQAvD_BwE

https://www.mdinaitalia.co.uk/49810051A.html

https://www.redfoximport.eu/onderdelen-parts/meters/cables-gears/

[koko64]

Thanks DP. Chasing them up.

[koko64]

Old Superlight wheels set aside for display purposes and will be cosmetically restored. Monster wheels were polished and painted for road use. I found a 20mm axle in my spares and a speedo drive was luckily located locally. Will provide pics soon.