World fastest sprinter?

Today I visited my friend who enters in the Dutch drag racing championship and who is one of the top 3 competitors. For this season (2011) he has build his engine from scratch and today it was testing time.



The first dyno runs were promising. After some testing with different reed blocks he pressed out an impressive 32,2 HP at the rear wheel.

Red line is HP

The green line should be ignored. The green line indicates torque, but because the computer was not hooked up to the any RPM gauge, these readings are false. Still mighty impressive.

As you can see by the dyno graph the transmission adjustment is off by a little (peak power at 140 KMPH). Meaning that it is still a bit heavy on the vario weights. Because the priority was to test all sorts of different reed blocks, the transmission wasn't adjusted to a perfect setting. This will be fixed in the near future.

Like I said, this engine was build from scratch (even the case!) and the only thing that is really related to a scooter is the transmission, all other parts where hand build or came of other, bigger 2-stroke bikes.

Here are some pictures from his project.

Update: The engine uses a stroke of 47mm and has a bore of 50mm (~93cc). Because the 50cc cases will not hold over 46mm stroke (which is already tricky), the cases was made from scratch too.

No needle bearing, just the needles

Lightweight aluminium frame

After "a couple more" hours this is more or less the end result.

See how the varioside has its own bearing

If you have so much power in such a light frame (39 kg ready to drive), you need to have some decent brakes. In the pictures below you can see an adjusted mini bike (Polini) brake caliper and brake disc mounted on the home made case. The wheel is from a Piaggio Typhoon (50cc).

I think it is an ingenious system!
Here is overall picture.

I saved the best for last. Some movie clips! It was quite windy today, but I think this clips show the huge speed potential. Too bad that the quality did go down by so much... I have to update to a real FHD camcorder some day... I hope you can still enjoy!

Setup:
- Cylinder from MX motor (increased to 50mm bore)
- VHM cylinder head
- 47mm stroke crank (Honda MB, Custom made axes for the vario use)
- Custom made cases
- 34mm Mikuni TMSS carb
- Polini Overrange
- Custom made reedblock (carbon reeds)
- Ignitech ignition with custom ignition curve + custom rotor.

*Custom = designed by the owner of this engine + made by the owner.

Stay tuned!

Bram