Gearing

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Smudge
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Main scooter: Vespa GTS
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Wed Oct 21, 2020 8:47 pm

I was gonna use 24/68 but that clutch gear is no longer available. 23/65 is the same ratio so I will do that but I am just wondering if there are any advantages/drawbacks to either ratio? TIA.

Scooterindo
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Main scooter: Cutdown Bitza
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Tue Nov 17, 2020 4:35 pm

Depends on the engine set up you're planning to use.

I used to run a 23/65 primary drive on my old 177 engine which had the 28mm carb reed valve crank and all the bells and whistles - acceleration was amazing but it couldn't maximize at the top end and flatted out.

I now have another 177 engine and instead have gone for a much milder tune standard 26mm carb standard crank and a 23/66 ratio using an 11 inch rear wheel. Overall this tends to perform much better right across the board.
Old Skool Cool

Smudge
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Posts: 9
Joined: Sat Feb 29, 2020 4:53 pm
ebay user ID: marsm4537
Main scooter: Vespa GTS
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Wed Nov 18, 2020 9:55 pm

Thanks for the answer. 24/68 gives exactly the same gearing as 23/65. When I finally get the Pinacso 250 in the scooter it might have to change again. I just wondered why Piaggio preferred more teeth on the cush.....reliability? Thanks.

Good gearing calc, put in your box and wheel size(different tab at top). French but colour coded and easy to use.
http://gearingcalc.free.fr/

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mawso
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Location: Harrogate
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Sat Nov 28, 2020 10:02 pm

I was running 23/65 on early PX125 gears, straight cut primary and clutch, have just dropped to 22/65 straight cut. 23/65 worked well with SIP2 and 24mm flat body carb, cut crank on a ported Malossi 166 the smaller carb and pipe gave it the torque it needed, it didn't do that well up steep hills though so was probably a tooth too far. Have a 100/90 x 10 to put on back but maybe that will just take it back to similar ratio of 23/65 lol

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