2moto

Innovation on 2 wheels

Norick Abe YZR-500 Replica

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The spiritual successor to the RD-350

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95Racer: 95bhp and 95kg

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Norick Abe YZR-500 Replica

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The spiritual successor to the RD-350

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YZR-500 Frame Kit

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The spiritual successor to the RD-350

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Engine development

One of the items we identified pretty early on was that we wanted to shorten the left side of the engine. This is where the starter gears, flywheel, and generator live. To save weight, we wanted to eliminate the starter and its associated gears and so went a little bit further.

The tuned engine now has a shorter crank with a new, one-off flywheel and a light weight generator. This allowed us to shorten the left side engine cover considerably.

Here is a picture with the new flywheel installed on the shortened crank. The remaining flywheel mass is now located much closer to the centre of the engine.

The hole in the middle of the modified cover is for access with the external starter.

The next set of pictures show the difference between the stock flwheel and the replacement we are now using. It has about a third of the inertia and also weighs a lot less. We also make one that has even less inertia but it makes the engine less happy.

So from left to right:

  • This is the lightest version of the flywheels we’ve tried so far. It has probably just slightly too little inertia, although it may work well at certain tracks. We will track test it in 2008 more thoroughly. The black band around the centre are the new rotor magnets imbedded in carbon fibre epoxy. It has just under a quarter of the inertia compared to the stock one.
  • This is a modified stock version which has the recess for the sprague clutch machined off. It is 600 grams lighter and has 70% of the inertia compared to the stock one.
  • The left most one is the stock one. It weighs 2.2 kg and has an inertia of 3.25 kg.dm2. The starter gear and sprague clutch has been removed in this shot.

You can also see the difference in the generator stator. The replacement produces about 200W which is still plenty to keep the battery topped up and run the ECU, fuel injection, fuel pump, and dash logger.

Eliminating the starter system and running a smaller generator also allows us to run a much smaller battery. The picture below shows the 3 different batteries that we’ve used.

From right to left:

  • stock battery, 4140 g wet weight
  • what we used last year, still running an on-board starter and standard generator, 2660 g
  • what we are using now with the light weight generator and no on-board starter, 890 g

That means just in battery weight we saved over 3 kg. Quite a difference! All in pursuit of more power and lighter weight.