Interesting DT175 electronic ignition conversion by Rex's

[Speedshop]

We were asked to do an electronic ignition and 12 volt conversion to a points model DT175.

Its very simple, we took one of our Electronic Magneto Control Units from our RMK-3 kit, re tweaked the timing curve for the smaller revvy 175 engine. Then we threw away the points and condenser.

A quick rewind of the points source coil so instead of supplying 75 volts at 1.5 amps for points it now supplies 300 volts  for CDi and hey-presto! 

We rewound the lighting coil to give much better low rev output.

 

 

 

EMCU:

We don't intend offering this as kit unless there is very sustained demand for it. We did it just as an exercise and to prove it works.

www.rexs-speedshop.com

 

 

[blackhat250]

Does it still use the same flywheel, [ points]  or do you need to change it to a cdi flywheel for the signal,,

[Speedshop]

Same fly wheel. The EMCU, (electronic magneto control unit) looks at the output coming from the source coil and works out the timing according to the AC frequency. This unit is basically a CDi unit however as there is no separate 'fire' signal it must calculate the timing based on engine speed. This is a function that standard CDi units don't have. We can schedule and change the timing for many different applications and give it 2 or 4 stroke timing curves again this is not possible with standard CDi units.

We call this system an "Electronic Magneto" as its self generating using a magnet passing a winding to make its power in the same way as a traditional points magneto, only there are no points instead, an electronic timing controller. 

 

Although I say you can't change a the curve of a stock CDi unit thats not strictly true. When we were developing our DT175 replacement Cdi unit we did play about a lot with it and could change it. However we took the decision to stick with the standard timing curve that Yamaha used. 

I hasten to add, its no good coming to us and asking for a CDi that goes better. If you say to us here is a timing curve I want with the RPM and timing advance data then we can produce it (if we have data we know works then we can use that). We are electronic engineers not engine tuners! With our XT500 kits we worked with several racers to get the Dual Power system so it out performs even the digital internal rotor kits. We did the maths and electronics the racers told us where the timing needed to be.