Lambretta Atomic mini reed-valve kit

Lambretta Atomic mini reed-valve kit

thumbnail thumbnail thumbnail thumbnail thumbnail

Click on photos.

Ready to order?


Not available now, sorry.

You can also contact us about this product.



  • 101208 (150/175cc)
  • 101209 (200cc)
295 grams


  • I bought one a while back to fit to an old school Yamaha 200 kit. Back in the day, the DT175 piston for the kit had to have the reed valve windows welded up, so I bought one of the Atomic reed manifolds to save messing around with the piston! It fitted with no alteration to the manifold or the barrel, even the port to manifold area was virtually spot on!
  • I ran one all last year on my (Yam pistoned) Rapido 230. No cutting of fins and plenty of clearance with a 30mm PHBH and remote filter. Mine is a touring set up in a S1 so not lightening quick pick up/acceleration but it's no slouch either and the fuel consumption is equivalent to others in our group who are running smaller engines (i.e., around 12 mile 1L). Hope that helps.
  • Fitted one to a Vega Casa 80 kit. Faster, smoother, quieter, more torque.
  • [Customized for a Lambretta Luna Starstream]: The Atomic reed block itself needs fettling to fit the Starstream barrel, but not much. My impression is that it is a better quality job than the [other company's] unit.
    -did you get the Mini Atomic? Very little fettling was needed on my Starstream barrel. 
    -The future is ScootrRS Mini Atomic Reed Valve. No fin cutting & no packer needed between inlet & reed valve, just drilled out holes to 8mm & elongated the back hole slightly. Manifold mouth is real small, so plenty of scope for matching to inlet, I'm just mocking now so i'll post some more pix later ... 26 PHBH carb no issues.

Atomic Performance high-quality bolt-on mini reed valve kit for standard Lambretta cylinders.

We have 2 reed-valve kits, this one and our larger Ultimate reed-valve kit.

The 'mini' kit is very easy to mount because no cylinder fin cutting is needed as with larger reed-valves.

What is a reed-valve? Basically a flap that opens and allows fuel in as the pressure in the cylinder needs it, then is pushed closed when not needed. You gain power and responsiveness down low, a huge improvement in fuel efficiency and no spit-back from the carb. People making the change rave about the smoothness of the power delivery.

You do not need a highly tuned motor to use this kit. It is great for regular motors too.

The kit includes everything needed.


  • good quality reed-valve
  • fits under the panel
  • no need to cut fins on your cylinder
  • rubber manifold with 34mm opening to fit our PWK 24-30mm carburetors (might also fit Dellorto 26-30 PHBH, VHSA 28, Mikuni TM24-30 but check your carb first)
  • 200cc manifold comes pre-matched to an Indian GP200 inlet; the 150/175 type is pre-matched to an Italian 150. You can open either type wider.

Reed-valve features:

  • good quality Atomic reed-valve for Minarelli horizontal. We also have spares.
  • alloy body
  • fiberglass reeds for optimal Lambretta performance (not carbon for super high RPM motorbikes)
  • rubber coated

See our tech notes for modifications needed.

Choose an option based on your original bolt pattern, 200cc or 150/175cc.

Tech Notes

  • Check your jetting when making the change. You usually need to upjet a lot. See our tech page for how to do a plug chop.
  • Match your cylinder inlet port to the new manifold, and open the manifold as much as you want to allow more flow. 
  • A standard Lambretta only opens the inlet port when the piston is out of the way. To take advantage of the reed-valve you should make some changes to allow fuel to enter whenever it is needed. You do that by drilling 2 large holes in the piston inlet side (or use a piston already made for a reed-valve) such that you can see into the piston through the inlet port. You can also add a boost port in the cylinder up from the inlet to the top of the transfer ports. Raising the exhaust port slightly will help increase power. Please consult a local shop for tuning assistance.

Your starred items:

Question? Comment? Help improve the description of this item?

Share this: Email | fb share | tweet


Your stock settings: