Bombus Speedshop

Bombus Speedshop
Wrenchin' without supervision since the seventies...

tisdag 17 januari 2017

Flywheels

To change ignition/charging system is a big thing when you go performance on a Zündapp.
The use of analog system with points ain't so appealing when cool performance parts are added.
Maybe not so necessary but it feels good to upgrade. Psychology is a huge part of tuning.

One thing when doing this is the possibility to have a advanced programmable ignition and just a rotor instead of a flywheel.
Those extreme systems have pros and cons depending on the needs.
Programmable ignition, low rotating mass but often no charging like the PVL system, these system are mainly for race use.
For street application there are many alternative as well.

Lower rotating mass with a really peppy throttle a nice sounding feature  but with the downside of really poor driveability outside a track.
Hard to start and very low torque.
So here some consideration must be made.

Back in the day when I built my 5 speed engine I went for a Chinese copy of the Bosch CDI system.
Haven't missed a beat over the years but its a 6V system and now I wanted a 12V system instead.
So I bought the now very popular Kokusan system with 12V output.

With so many systems I put some flywheels on my scale to get some facts.

353g - PVL (No charging)
744g - Kokusan (6V or 12V)
832g - OEM Bosch (3 speed)
943g - China copy on Bosch CDI
360g - HPI  with charging
(350g and 280g extra flywheel weights are available  -> 710g/640g)

So for me it have two upsides with the change to Kokusan, 12V and a bit more peppy throttle with just under 200g less rotating mass.

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