1968 Li125 S


After surfing around the internet and reading magazines and books I narrowed my tuning choices down to either an Imola185 kit or an AF Rayspeed TS1 225. The Li125 casings have a smaller spigot opening (approx. 70mm) that will not accept the large spigot of a 225 barrel. The amount of parts that are necessary are almost the same for either conversion although the TS1 conversion would also require new cases (see pics below). New parts will include

  • Barrel to replace the original 125 barrel - both kits come with a reed valve set up including an intake manifold. The Imola includes a GP/SX head and the TS1 requires a reprofiled GP head which is not included.
  • Crank - The Li125 Special shares a crank with the GP125/GP150 series of bikes which is supposedly stronger than an Li model. I will probably replace it with a GP200 version which is stronger and has a thicker flywheel taper.
  • Bearings - Thought I'd replace them all as for all I know the existing bearings are still the originals from the 1960s.
  • 12v Electronic ignition set up - The standard Li points system are prone to fluttering at the high rpms that a tuned motor would produce and must be replaced with an electronic system that has no moving parts other than the flywheel itself. 12v will make the lights much brighter too.
  • Aftermarket carb - Both kits are able to take much larger carbs than the 20mm SH1/20 carb that is standard.
  • Gearbox primary drive - I need to drop the gearing down to about a 4.00:1 ratio in forth gear to take advantage of the new power. The smaller toothed gear on the end of the crank and the larger toothed clutch bell will have to be replaced with new parts to make this change.
  • Exhaust system - The Li system would be too restrictive on either of these barrels and I know that the TS1 has a different attachment flange than a standard exhaust.
  • Dampers on the front suspension and the possibility of a partially hydraulic disk using a Vespa Grimeca fork mounted master cylinder and a converted TV disk...we'll see.

My first purchase has made my choice for me. I bought a set of GP case from Scooter Cafe for only $150. I received the main casing, mag side flange, and chaincase in under 4 days. The quality of the castings is very good with only a little bleed at joints. The casings came with 4 studs at the rear wheel & no brake cams, 3 studs at the mag side flange, and two studs on the chaincase side. Also the gearbox retainer plate was included. The only strange thing is there is no serial number on these casings - I doubt the Department of Motor Vehicles would approve but they'll never see it.

The transfer openings on the GP200 casings are larger than my Li125 casings. The crankcase mouth is about 74.5mm in diameter. Hopefully this will be a good base to up the power from the standard 7hp of the Special

Below is a shot of the original LI crank mouth still in the bike while I was replacing the original piston.

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