Tomos A55 Performance

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Revision as of 04:08, 18 July 2013 by Nikg (talk | contribs) (→‎Exhausts)
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This wiki page is a collection of performance parts for Tomos mopeds with the A55 engine.


The a55 is easily the highest performance factory engine that tomos has produced. Although reverting back to a piston port inducted cylinder from the previous reed valve inlet a35, the a55 produces better torque and midrange than it's predecessor. Additionally, the a55 has enormous top end potential, and is a very capable 50:50 engine.

The a55 is also the most sought after tomos engine when it comes to high end performance, due mainly to the massive cases and case transfer area that is available from the factory. This increased case area enables large cylinder kits with massive transfer area to be fit without fear of needing to weld additional material on for proper gasket matching and sealing. This large transfer area isn't just for massive cylinder kits however. Even the stock cylinder benefits from large transfer area, and is one of the reasons why a55s are so fast when set up properly.

a55's are restricted from the factory through gearing and exhaust. by switching out to better gearing and a better exhaust, you can go over 45mph quite easily. i personally (mattology) made 48mph on radar with an a55. stock ports. there is lots of potential in that cylinder.

Any performance a55 build should include a balancing of the clutch drum or replacing it with the a35 variety if it is determined to be out of round.

Stock A55 port map and porting info,2964145,2964145


  • This kit will fit the 2007 and up Tomos A55 motor that has 2 bolts holding on the intake manifold. If your moped has 4 bolts holding on the intake manifold to the cylinder is our reed valve cylinder kit part #505040 (does not come with wrist pin bearing). If bought, I recommend the 17.5 Dellorto PHVA carb to get power out of this kit. $180
  • A55 cases have much larger area for transfer ports compared to A35 and A3 cases. This makes them prime candidates to install the larger Puch kits on them, such as 74cc gilardoni, or metrakit cylinders.


  • Technigas Next R. Requires custom mount.
  • Biturbo. Easy fit.
  • Tecno Bullet. Similar to Biturbo, doesn't brake as easily.
  • Motomatic, MLM, WEAK-ENDS, Treats, custom

Package Deals

  • New performance package for the Streetmate, Revival and Revival TS with A55 engines. High flow performance exhaust, 28 tooth rear sprocket and a #56 fuel jet designed to deliver higher performance from your A55 engine. $170


Front sprockets can also go 24, 26, 27, 28(from treats) and 31tooth ( need to modify or run without side case for this one and it wont fit with the stock flywheel )

Rear sprockets 26, 24, 22 and 20 tooth (Need to bevel the rear wheel for chain clearance for this one folks)

Tomos Revival, Streetmate, and Arrows all use a different front sprockets and the Arrow uses a different rear sprocket from all other Tomos'(scooter wheel)

Carburetors and Air Filters

  • A55 Carburetor Speed Kit Upgrade This is everything you need to upgrade your new Tomos A55 Sprint, St, LX, Revival, Arrow, and Streetmate. $29.00. Best when used in conjunction with a new performance pipe and a 22 tooth rear sprocket. Includes:Larger Infuser, Larger Idle Jet, Larger Main Jet, and UNI Pod Air Filter
  • PHVA jets. These are the larger 6mm Dellorto main jets used on the PHVA carburetors found on the new Tomos A55. #56-#90


Please see Racing transmission fluid for your Tomos.