Objectives

The objectives of this project are to study, develop and maybe sell a programmable box for the Yamaha 2 strokes series : TZR125, TZR250, RD350LC (also known as RZ350) and the RD500LC (also known as RZ500 or RZV500). The idea is to build a box that could be a direct replacement component for the Yamaha controller. As I've got two TZR250 (2MA and 2XT) and an RD500LC (47X), the YPVSBox will be tested on these machines first. It works on TZ250 using a standard Yamaha servo motor (tested on 93 and 96 TZ250 contact me if you could supply TZ250 specifications).
The goals are:

be as good as the Yamaha box
be programmable for every parameters

YPVS valve positions (fully opened and totally closed)
RPM for the beginning of the valve opening
RPM for the fully opened position

Developing the hardware and software, why not include the shift light?
The configuration of the YPVSBox is done using a PC and the RS232 serial port.

GUI

The Graphic User Interface has been develop in C++ and is running and currently in test under Windows XP and Window 2000. It is a send alone application with a typical windows interface. By now the only supported language is English but a French version will be developed later.
We also take the number of spark per revolution in our computation so the box is working for the 2 sparks/rev bikes like the RZ and TZR250 parallel twin but also for the TZR125 (single cylinder) and TZR250 3XV (V twin).

There is actually 6 zones:

RS232 serial port configuration zone and dialogue window button
The Valve control zone for the input parameters and the compute button
The Flasher control zone and the compute button
The results zone and sending button
The Edit zone for viewing the message from the YPVSBox
The tuning zone for maximale and minimal range for opening.

For more detailed views, go to the "how it works" zone.
You can download the setup file (see icon below).

Hardware

The YPVSBox is based on a MICROCHIP PIC (18F) processor for the capture of the engine RPM and the potentiometer of the YPVS stock servo. The servo motor is driven by a H-bridge. We are using a minimum number of components and we are also choosing the most integrated ones to improve the reliability. The prototype (updated 10/06/2012) is currently in test in the Lab using wave generator, oscilloscope and 12volts power supply. The embedded software is OK but some timing needs to be improved to smooth the behaviour of the servo-motor.

Application

The first test is made with the TZR250. We use a TZR125 dashboard so a single spark per revolution. For more detailed views, go to the "TZR250" zone.
After the bench presented at the RD500LC Club meeting the 1st of July 2007 now a complete version fully operational on the bike. It includes:

TZR125 or TZR250 or RZ500 dashboard
YPVSBox
direct plug in on the bike wiring loom
laptop for YPVSBox configuration

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