Suzuki SV650 Riders Forum banner
1 - 10 of 10 Posts

·
Registered
Joined
·
109 Posts
Discussion Starter · #1 ·
Hi all,

I'm playing around with some data acquisition gear and am having only moderate luck getting a decent tach signal in the upper half of the rpm range using a simple inductive clamp.

So, I want to go to a hard connection, probably using the tach signal from the front coil.
My gear can handle that, but warns against doing so for a CDI system.

I believe this system is NOT CDI, but I'd love to hear someone confirm that, if possible.
It looks like elec control of very standard coils, but I'm open to rebuttal or encouragement.

I'd like to get some data this aftn while off from work and enjoying 80 degrees.
I'm only going to get so many of those in Jan.

Thanks
Roger
 
G

·
cdi tells coils when to fire.tach wire comes from cdi and goes direct to coil.splits in to 2 and other goes to tach.
 

·
Registered
Joined
·
109 Posts
Discussion Starter · #3 ·
Thanks for the reply.

The layout and wiring I believe I have down. What I wanted to clarify was rather this was a true Capacitive Discharge Ignition
(a lot of people incorrectly refer to all electronic ignitions as CDI) or merely a regular electronic ignition. One will trash my data-acq,
and the other won't. None of my manuals seem to spell it out.
 

·
Registered
Joined
·
109 Posts
Discussion Starter · #5 ·
Thanks just the same.

Yeah, this is a tough one. Haynes and Clymer merely say digital transistorized. That describes almost all non magneto, points and diesels though, so it's not much help. I need to see what the factory manual says, if anything.

I'm going to guess it's not CDI. First, the ignition controller is a LONG ways from the coils. That's generally ok for regular electronic or points, and the charging curve is fairly slow. CDI's dump a very large fast impulse through the coils, and it's rather large to be present on wires this small and long.

Also, I went through the AllData books and it seems to differentiate between TCI and CDI, calling this one a TCI. Here's hoping. If I ever find out definitively, I'll post back. I'm going to punt and pull it at the tach terminal. It appears to be close to ground, even factoring in a little bounce, and thus shouldn't do any harm.
 
G

·
here is stock manual;
the fully transistorized ignition system consists of signal generator,ignitor(including a 8-bit microcomputer),tps,2 coils and 2 spark plugs.
the induced signal in the signal generator is sent to the wave-form arrangement circuit and the I.C. recieves this signal and calculate the ignition timing properly.the I.C. outputs the signal to the transistor of the ignition coil output circuit which is connected to the primary windings of the ignition coils which is turned off and on accordingly.thus,it induces the secondary current in the ignition coil's secondary windings and produces the spark between the spark plug gaps.
 

·
Registered
Joined
·
2 Posts
The system is not a full CDI system .
jh
www.jhsracing.co.uk




rogsvr said:
Hi all,

I'm playing around with some  data acquisition gear and am having only moderate luck getting a decent tach signal in the upper half of the rpm range using a simple inductive clamp.

So, I want to go to a hard connection, probably using the tach signal from the front coil.
My gear can handle that, but warns against doing so for a CDI system.

I believe this system is NOT CDI, but I'd love to hear someone confirm that, if possible.
It looks like elec control of very standard coils, but I'm open to rebuttal or encouragement.

I'd like to get some data this aftn while off from work and enjoying 80 degrees.
I'm only going to get so many of those in Jan.

Thanks
Roger
 

·
Premium Member
Joined
·
947 Posts
jhsracing said:
The system is not a full CDI system .
jh
www.jhsracing.co.uk
That's right, a CDI system would fire a fairly high voltage surge to one side of primary winding in the the coil with the other side grounded. The SV has +12 volts on one side of the primary and the transistor in the controler switches the other side to ground. When the transistor opens the ground it fires.
 

·
Registered
Joined
·
16 Posts
Marc said:
That's right, a CDI system would fire a fairly high voltage surge to one side of primary winding in the the coil with the other side grounded. The SV has +12 volts on one side of the primary and the transistor in the controler switches that to ground. When the transistor opens the ground it fires.
True. It's usually easy to tell as a CDI sytem would have the coil connected differently, the positive terminal would be supplied by an inverter in the CDI box.

FYI Your data unit tells you not to connect it to the coil of a CDI system, as the coil supply is typically in the region of 350V or so, and that'll soon knacker a unit expecting 12V. Also if you ever need to know, in a conventional system, (points, transistorised, whatever), the plug fires on discharge of the coil, field collapse, a CDI sytem fires on coil charge - big pulse from capacitor, very fast coil charging, fast field build up. Works well but the downside is short spark duration, falling out of favour now as mixtures get weaker.
 
1 - 10 of 10 Posts
Top