correct chain for 89 900 ss

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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steveT2
Posts: 65
Joined: Thu May 05, 2016 7:37 am
model: 750 Sport
year: 1988
Location: UK

correct chain for 89 900 ss

Post by steveT2 »

I'm thinking of treating the 900 to a nice Shiney gold link chain, can anyone confirm the chain spec, its on standard sprockets/gearing, 520/98 ?
Thanks
angelix
Posts: 338
Joined: Thu Nov 29, 2007 2:38 am
model: 907 I.E.
year: 1990
Location: UK

Re: correct chain for 89 900 ss

Post by angelix »

Original gearing (Final) was 15/37, which is way too tall for that engine. with that gearing @ 8500 RPM you would be going at 142MpH (Max RPM should be 9000)

I would go for a 15/39 or 15/40, you loose few miles at the top end (maybe 4-5) but you will gain some "umpf" around the mid range where the old SS900 has a couple of deeps in the torque curve.

to check if you like the shorter gearing you can "borrow" a 14T front sprocket which will work fine with the standard chainring and chain legth; 1T less at the front = aproximately +3T at the back so a 14/37 would be very similar to a 15/40

Bare in mind that the 14T would/could chew the chain on the long term (too much stress, especially on the of V2) , so it is prefereable to keep the 15T ; my suggestion is only to test the gearing before committing to a new complete setup.

with the 15/39-40 you will need to add a couple of chain links

I just did my SS750 (+2 at the back) and I like it better than before; the same goes for my 907ie, wher ebefore I had to keep changing 2-3 gears, now I keep the 3rd in and enjoy better the ride.
steveT2
Posts: 65
Joined: Thu May 05, 2016 7:37 am
model: 750 Sport
year: 1988
Location: UK

Re: correct chain for 89 900 ss

Post by steveT2 »

angelix wrote:Original gearing (Final) was 15/37, which is way too tall for that engine. with that gearing @ 8500 RPM you would be going at 142MpH (Max RPM should be 9000)

I would go for a 15/39 or 15/40, you loose few miles at the top end (maybe 4-5) but you will gain some "umpf" around the mid range where the old SS900 has a couple of deeps in the torque curve.

to check if you like the shorter gearing you can "borrow" a 14T front sprocket which will work fine with the standard chainring and chain legth; 1T less at the front = aproximately +3T at the back so a 14/37 would be very similar to a 15/40

Bare in mind that the 14T would/could chew the chain on the long term (too much stress, especially on the of V2) , so it is prefereable to keep the 15T ; my suggestion is only to test the gearing before committing to a new complete setup.

with the 15/39-40 you will need to add a couple of chain links

I just did my SS750 (+2 at the back) and I like it better than before; the same goes for my 907ie, wher ebefore I had to keep changing 2-3 gears, now I keep the 3rd in and enjoy better the ride.
Thanks for the info ........
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