General Category > Bike Builds, Rebuilds And Restorations Only
Primary gears 1200 Sport vs. Griso
mdagbro:
Hi
Been studying the specifications for my 1200 Sport and the Griso. They have different primary gear ratio but it's compensated in 5th and 6th gear on the Sport, so the total engine/rear wheel ratio is almost identical. The Griso has 26/35 ratio on the primary, while Sport has 24/35.
My idea is to swap primary gear(s) on my Sport to reduce engine revs. Tables below show the gear ratio for both bikes and the last one is a theoretical calculation my Sport with Griso primary ratio. My question is, since the 35 teeth wheel is identical on both bikes, how can the clutch shaft wheel have 24 and 26 teeths, respectively? Can I really achieve this with the Griso (26) clutch shaft, without any other modification?
Griso 8V
Prim 1,346:1 (26/35)
I 2,235:1
II 1,700:1
III 1,348:1
IV 1,115:1
V 0,968:1
VI 0,862:1
Final 3,667:1
Total@6th gear 4,255:1
1200 Sport 4V (per cyl, why ..? :violent1:)
Prim 1,458:1 (24/35)
I 2,235:1
II 1,700:1
III 1,348:1
IV 1,115:1
V 0,935:1
VI 0,8:1
Final 3,667:1
Total@6th gear 4,278:1
Sport w. Griso primary
Prim 1,346:1 (26/35)
I 2,235:1
II 1,700:1
III 1,348:1
IV 1,115:1
V 0,935:1
VI 0,8:1
Final 3,667:1
Total@6th gear 3,949:1
Exploded views:
Griso
Clutch shaft Z=26 (pos 1):
https://us.fowlersparts.co.uk/parts/5719249/griso-griso-griso-s-e-1200-8v-chassis-number-prefix-zgulsg01-2005-2013-griso-s-e-1200-8v-chassis-number-prefix-zgulsg01-all/clutch-shaft
Drive gear Z=35 (pos 2):
https://us.fowlersparts.co.uk/parts/5719285/griso-griso-griso-s-e-1200-8v-chassis-number-prefix-zgulsg01-2005-2013-griso-s-e-1200-8v-chassis-number-prefix-zgulsg01-all/primary-gear-shaft
1200 Sport
Clutch shaft Z=24 (pos 1):
https://us.fowlersparts.co.uk/parts/5716816/1200-sport-1200-sport-1200-sport-8v-chassis-number-prefix-zgulpj20-zgulpr00-zgulpr01-zgulpj01-2006-2013-1200-sport-8v-chassis-nu/clutch-shaft
Drive gear Z=35 (pos 2):
https://us.fowlersparts.co.uk/parts/5716854/1200-sport-1200-sport-1200-sport-8v-chassis-number-prefix-zgulpj20-zgulpr00-zgulpr01-zgulpj01-2006-2013-1200-sport-8v-chassis-nu/primary-gear-shaft
Mikael
derekwiltshire:
Looks to me like you might lose some acceleration in the sport by making that change, though yes it would lower engine revs for any given speed
Sent from my iPhone using Tapatalk
beetle:
Why not just buy a Griso gearbox?
mdagbro:
--- Quote from: beetle on August 03, 2017, 04:21:00 PM ---Why not just buy a Griso gearbox?
--- End quote ---
The Griso has almost identical TOTAL engine/wheel ratio. Using Griso primary gears in Sport gearbox would improve the situation, lowering engine revs ... but naturally it's a trade off when it comes to acceleration.
But I spend more time running at constant speed than accelerating ... and never ever used the bike's acceleration to the limit, why I think it would suit me.
pete roper:
Sports certainly seem to be geared higher than Grisos. I thought the Breva/Sport primaries were higher but I'll happily defer to your research, it's been a long time since I worked it out.
Pete
PS. If you want a Griso gearbox I have a few.
Navigation
[0] Message Index
[#] Next page
Go to full version