Scooterotica

Morning all could you please give me some advice on gearing my li125 special it has a 175cc iron head with standard dellorto carburettor and 42 clubman exhaust it has a 15 drive sprocket seems to be very high reving screaming at 48 mph .cheers mick

probably the first thing i would try is a 16 front sprocket and see if your set up will pull in top gear ok, there are a serious amount of options, my pal has a 175 and he has fitted a close ratio gearbox and with a bit more tuning he is running a 19 front sprocket, a set up he realy likes, that is running an expansion exhaust which does give more power higher up the rev range.

You need to check what gear box and what sprockets you have front and rear.
This link will help you work out what gearing you currently have. I think you should be looking at a ratio of about 5.2
https://www.scooterhelp.com/tuning/lam.gear.calc.html

18/47 with a 125 special gearbox.

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hi,
if it is a Li125 special gearbox ( same as Gp125/Gp200)then it will be screaming on 15/46(6.13 o\all )sprockets. Harry Barlow recomended 18/47 (5.22 o/all) on that box for two 175 conversions he done for me , both using small carbs and clubman exhausts.

You will need an 82 link chain with 18/47. You could use 16/46 and see if the 175 pulls it ok


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18/47 on that gearbox and life is good. I have that same set up on 2 bikes right now. One running a Casa 185 and the other running a Gori 200 top end. Good pulling ratios for in town with out the 4th gear drop off you commonly get with over geared bikes.

16/46 is a cheap modification and in my experience works well on your set up.
You will need a stretched 80 link chain.

16/46 will give 5.75 o\all, still be very revvy.
his set up should pull 5.22 quite easy.