Revision as of 03:44, 18 July 2013 by Nikg (talk | contribs) (→‎Maintenance Information: some duder changed it from what is says in the manual)

The Tomos A55 engine is the latest available model, introduced in 2003 and found on all current Tomos mopeds. It shares many similarity to its A35 brethren but has an all new cylinder, piston, carburetor, intake manifold, and exhaust. The engine has a nikasil plated aluminum piston-ported cylinder. The new cylinder has an exhaust port angle of 25* so exhausts made for the A35 will need to be bent in order to fit. The new Dellorto PHVA carburetor allows for more accurate fuel mixture than previous models and the exhaust has a built in catalyst. Most of the upgrades on the A55 were done in the sake of cleaner emissions, however it is the most powerful Tomos automatic engine to date. The transmission is basically the same as the A35 aside from some small improvements such as larger cutouts for the cylinder transfers.

Technical Specifications

  • A55 Engine
  • 49cc two stroke
  • 38mm X 43mm Bore/Stroke
  • 10:1 compression ratio
  • Automatic 2 speed transmission
  • Dellorto PHVA 14mm Carburetor (#55 main jet, #25 pilot, #40 choke)

Maintenance Information

  • Gearbox oil: Type A or Type F Automatic transmission fluid. 10 fluid ounces
  • Spark plug: NGK BR8ES
  • Spark plug gap: 0.8mm

Oil Lubrication

  • Gear box oil change: 250mi/2mo, 1100mi/3mo, 2200mi/6mo and 4500mi/12mo
  • Bowden: As necessary
  • Chain: 250mi/2mo, 1100mi/3mo, 2200mi/6mo and 4500mi/12mo. Chain should have 10mm free play in the up or down position.


  • Rear fork bearing bushings as necessary.
  • Steering bearings: 4500mi/12mo

Shim Placement in Clutch

see following image. http://i33.photobucket.com/albums/d75/VWBILL211/Tomos/78Tomos053-1.jpg

Performance Tuning

Tomos A55 Performance