AC powered CDI ignition advance?

Thread Starter

Classictrial

Joined Aug 23, 2010
30
The CX500 was as you say an oddball bike, but seems very reliable and here in the UK was a very popular choice for motorcycle courier work when they were current.

A source of parts in the UK is David Silver spares, and in Holland CSMNL (?) may be able to assist............but you have probably heard of them if looking for Honda parts in Europe?
 

marshallf3

Joined Jul 26, 2010
2,358
The CX500 was as you say an oddball bike, but seems very reliable and here in the UK was a very popular choice for motorcycle courier work when they were current.

A source of parts in the UK is David Silver spares, and in Holland CSMNL (?) may be able to assist............but you have probably heard of them if looking for Honda parts in Europe?
Thanks, there are a ton more over there and in Canada than here mainly due to the reliability factor. THose couriers needed something reliable that handled well and got good gas mileage. We average around 50 or so U.S. mpg on ours, it was one of Honda's first "lean burn" engine concepts.

A great deal of parts are still available from a lot of local suppliers, however a few we have to send overseas for. eBay is always full of used parts as well. People find these old bikes in barns, determine they're 30 years old and think they're junk because they look so strange and already have 18,000 miles on them. Those are just babies, in many cases you can put gas in the tank, replace the battery and they'll start right up even after sitting all that time yet they get junked &/or eventually parted out.

We've got 2 main forums on them, one here in the U.S. and another in Australia so there's plenty of support. These have to be the easiest bikes ever built to work on, even in the rare case you've got to drop the engine that just adds a half hour or so if isn't your first time to do so. Aside from a couple of slightly leaking seals everything I've had to do to mine was consmetic.

They run as smooth as silk, the only surprise being around 5K or so when the ignition kicks into the higher voltage mode with a little more advance. With the "sideways from usual" engine they draw a lot of onlookers in the parking lots - even the Harley riders like them as many ownded or knew someone that once owned a Silver Wing model in full dress.
 

Thread Starter

Classictrial

Joined Aug 23, 2010
30
Hi
Many China made motorbikes use AC CDI based on FM4213. This IC compares positive edge and negative edge of the trigger pulse to define advance timing.
The original IC is MN 4213. Here is the link
http://www.fmsh.com/english/products/FM4213_ds_eng.pdf
Thanks.........I guess thats how add on CDI's that can be programmed (such as Vortex) work? Are these systems fully digital, or analog with electronics to convert the triggering pulse to approximate digital?
 

marshallf3

Joined Jul 26, 2010
2,358
This IC compares positive edge and negative edge of the trigger pulse to define advance timing.

Perhaps, but it still sounds somewhat pickup specific. It is definitely something to look into though, given the proper conditions it could come in handy some day.
 

legac

Joined May 4, 2005
54
Thanks.........I guess thats how add on CDI's that can be programmed (such as Vortex) work? Are these systems fully digital, or analog with electronics to convert the triggering pulse to approximate digital?
Hi
It is analog. Please see attached. Please note that there are 3 factors which determine the Time b/w the positive and the negative edge of the trigger pulse. They are the size of the iron core of the pickup coil, the size of the magnet on the volant and the RPM.
 

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Thread Starter

Classictrial

Joined Aug 23, 2010
30
Thats what I thought..........are units such as the Vortex and PVL AC CDI systems that are programmable also analog then?

If I have this right there are quite a lot of disadvantages when comparing analog to digital, but I guess if its possible to program analog system to suit specific requirements, then for dirt bike applications they are fine?
 

jaguar57

Joined Jan 14, 2014
1
I am the owner of the dragonfly75 site which discloses the Kawasaki design of AC CDI. That design advances to around 23 degrees BTDC at around 3500 RPM. If you want it to advance more then increase the gate resistor from its current 390 ohm value. This design works best for engines with top RPM between 8,000 and 9,500.
 
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