Existing 4 stroke engines

Here is a list of the current existing 4 strokes engines (not comprehensive) that were imported in the US :

Biland :

  • Engine type : 2 cylinder 4 stroke
  • Power : 34 hp @ 9,500rpm
  • Torque : N/A
  • Displacement : 124.8cc x 2

Personnal note : Not used anymore in the EU, you might see one or two during track days. Pretty fast, pretty unreliable

Swiss Auto 250 (Carburator) :

  • Engine : Single cylinder 4 stroke with balance shaft
  • Power : 35.5 HP at 9’000 rpm
  • Torque : 28Nm
  • Displacement : 249.6 cc

Personnal note : Really fast, tons of torque, keeps with the KZ2 on most of the tracks. Same weight as a Rotax.

Swiss Auto 250 EFI :

  • Engine : Single cylinder 4 stroke with balance shaft
  • Power : 38 HP at 12,000 rpm
  • Torque : 28Nm
  • Displacement : 249.6 cc

Personnal note : The EFI allows for multiple power bands (15 to 28hp in leisure mode, up to 40hp in competition mode). It is distributed and used by Sodi on their high end leisure karts. Fun fact, Sodi used two of them on the same bi-seat kart they used during the SWS World Final. Still not great on reliability (needs a rebuild every 40 hours), which makes them a meh choice compared to the Rotax Max even in Leisure karting.

Vampire :

  • Engine : Single cylinder 4 stroke
  • Power : 34HP at 10,750 rpm
  • Torque : N/A
  • Displacement : 249.6 cc

Personnal note : Seen one running in France back in 2008, when it was hyped. Nobody raced those, and they seem very similar to the SA250.

Oral :

  • Engine : Single cylinder 4 stroke
  • Power : 34HP at 10,500 rpm
  • Torque : N/A
  • Displacement : 249.6 cc

Personnal note : Never seen one IRL :man_shrugging:

Tech F1 :

  • Engine : Single cylinder 4 stroke
  • Power : 35HP
  • Torque : N/A
  • Displacement : 250cc

Personnal note : Lighter than a SA250 and a Rotax Max, apparently faster than the Vampire and the Oral. Never seen one IRL :man_shrugging:


  • Engine : Single cylinder 4 stroke
  • Power : 19hp
  • Torque : N/A
  • Displacement : 200cc

Personnal note : Oi bruv good engine innit ? I am French so I can’t possibly appreciate english engineering. :eyes:

As a conclusion, all those engines came out in 2005 - 2010, mainly because the FIA wanted to move from the archaic, outdated 2 strokes. Let’s say, it didn’t work well.


all motorsport is archaic and outdated. :slight_smile:

I should have put quotes around that statement. :grin:

Though 2 stroke is unfortunately not that environment friendly, and it was already an issue 15 years ago

No motorsport propulsion is environmentally friendly. :slight_smile:

the old 2-strokes don’t use starter motors, batteries, clutch material etc… so depends how you frame it on the environment front.

Obviously but it doesn’t mean you can’t try to make it better. I absolutely love 2 stroke engines, but I prefer being able to drive at all.
4 stroke with e85 biofuel could be a sensible direction

I don’t think it makes an ounce of difference. With regard to drive something or nothing, the green movement makes no distinction between 2/ and 4/. If it goes bang, that’s all they care about.

@tankyx where the normal stuff like the Hondas etc? This specific to racing series as opposed to general?

It was more about listing the other 4 strokes that are not tillotsons, that were developed for karting and imported in the US. The Hondas are not karting engines at first

Great overview…

2-strokes aren’t very racer health friendly, especially when used with leaded fuel (US). Too small in number to have any environmental significance - but of course that doesn’t stop the greenwashing FIA.

Wait until they start testing the tyre particle pollutants. Make 2/ vs 4/ debates almost irrelevant.

Dumb question most likely but is carbon black needed? Or is it just for looks?

Carbon Black does prevent a tire from losing its black color over time, but that is really only relevant in a non-racing tire that lasts for years. Structurally Carbon Black adds Abrasion Resistance, Stiffens the rubber and Cohesion between the molecules (less cracking and splitting).

In the late 90’s I was working for Bridgestone/Firestone. The Company was/is real big on training. Part of which was the development of Long Length Carbon Black Molecules used in the tire’s construction. It was stated that the Longer Molecule increase Abrasion Resistance and Improved Rolling Resistance. They could then make the tires Softer providing better Traction and simultaneously increasing tire Life.

I recently saw an Article from a few years ago talking about how Single Walled Carbon Nanotubes (SWCNT) might replace CB in tire manufacturing. Early test showed significant improvements over CB with far less material needed.

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As always, thank you.

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Lead and evaporative emissions will dominate our problems if the EPA or CARB ever take a good look at us.

Both have good solutions. Reducing particulate matter will require the end of iron cylinders and the use of synthetic oil at 32:1 or less mix ratios.