Mods and upgrades
- Stock carb is the PHBH28BD.
- A 34 mm carb on a 122 needs a larger manifold.
- Unsourced jet sizes stay marked To verify.
1993–2006 · two-stroke
Mods, with a source or not at all.
The popular 34 mm carburettor on a Type 122 is in here, beside the pipes, reeds and the other jobs people actually do. Each page is one area. A number without a source staysTo verify.
Carburettor
Stock is the PHBH28BD. A 34 mm carb on a Type 122 is an upgrade, and it needs a larger manifold.
02Exhaust
The expansion chamber sets the power band. A silencer swap, on its own, is not the same job.
03Reed valves
The block and the manifold are part of a 34 mm conversion. Reed clearance is still not published.
04Cylinder and head
Port timing, squish and a modified head volume are not published. Stock compression stays labelled as stock.
05Ignition and CDI
The two ignitions do not interchange. Type 122 timing in degrees is still not published. No pinout is printed here.
06Power valve
The RAVE makes a high-rpm engine rideable lower down. Opening speed is a control-unit fact. Removing a working valve has no sourced gain.
07Gearing
The two engines do not share a final drive. Count the teeth. A speed chart is not copied from a colour key.
08Clutch
The packs are different. A heavier kit is sold. Whether a tuned engine needs it is not measured here.
09Cooling
Stock thermostat and coolant figures are sourced. A larger radiator is not.
10Suspension, brakes and tyres
Stock tyre sizes, pad limits and fork-oil quantity are sourced. Sag, springs and upgrade parts are not.
11Fuel and oil
95 RON is the manual. The oil pump is a range that moves with rpm and throttle. A single premix ratio is not published.
12Restriction and full power
UK learner-legal is 11 kW. Open two-strokes in the brief are about 21–23 kW. This page says what the restriction is made of. It does not draw a wiring diagram.
13Reliability after tuning
The published mileages are planning figures for the two-stroke, not a shorter interval for a tuned engine. That shorter interval is not sourced.
Stock jetting and torque stay on the specs pages. Common faults stay onhacks. If a mod page is missing a figure you can source, send it.
Notes from readers
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