2 stroke general electrical question

[dthx]

25 HP (Mercury 25M refitted with an electric start)
So ....the starter turns the flywheel over and the Magneto sends a current of some voltage to the CDI Box
The CDI Box takes it and sends a timed current of some voltage to the coils
The coils amplify that and send that timed current of some voltage to the plugs
Questions:
Is that correct?
And if so.....will a service manual for the motor tell me what the specs are for those voltages?
I know I have to build a CDI adapter for my Volt Ohm Meter.

 

[jimmbo]

The link to this in the Sticky File goes nowhere anymore, so...

http://www.cdielectronics.com/troubleshootingguide/

 

[GA_Boater]

The link to this in the Sticky File goes nowhere anymore, so...

http://www.cdielectronics.com/troubleshootingguide/

Which stickie, jimmbo? Links change over time and sometimes need refreshing.

dthx - What kind of problem are you working on? CDI or switchbox motors don't use magnetos.

 

[dthx]

Thank you....
So...... this is a company actually called CDI that sells the electronic parts for ignition systems and the like?
I see that they have a trouble shooting guide for Their Capacitor Discharge Ignition products.....
If I get a Mercury service manual for my 25 ...do you think that they make the CDI box for Mercury?
And ....so the trouble shooting steps on their website would be the same for my engine?
Otherwise....I.m back to my original question for everyone.
If I've missed something I apologize....

 

[flyingscott]

What year is your motor and the serial #. What problem are you having? Under the flywheel are 2 small coils and a pick up it is a very simple system.

 

[GA_Boater]

CDI makes all types of electrical/electronic replacement parts. The iBoats store sells the parts.

The CDI Troubleshooting guide is for any switchbox forr your motor- It works the same as OEM, so troubleshooting is the same. A service manual has the same troubleshooting steps.

We need the serial number of your motor to point you to the correct switchbox.

Again - What is your problem? No sense saying the switchbox is bad when other parts of the ignition system can cause trouble and following the guide can pinpoint a fault.

 

[dthx]

Thank you everyone..
I have a 1998 25M (25Hp) Mercury 2 stroke SN 06592985
I put the muffs on the engine and started it in the driveway.
The motor has been fitted with an electric start.
The bottom cylinder is missing...but the plug will deliver a spark when running.
I know it;s missing because there is no change to the engine when I pull the spark plug wire off.....but there is a spark
I'm trying to find out how to test the electrical system from it's beginning all the way down to the plug.
I guess I was wrong about saying magneto.....
So..what delivers electrical power to the CDI Box?....is that the stator?
.I have ordered a spark tester from Mac tools,,,,one with which I can actually measure the spark length.

 

[dthx]

Thanks to All..
From what I understand, The flywheel has magnets around its perimeter that will pass close by the stator windings and produce an electrical current that then goes to a CDI Box and then to the coils and then to the spark plugs...correct?
All those values can be measured I suppose.
If I buy a 1998 25HP Mercury Service Manual online ...will it have all those values?

 

[racerone]

?-------CDI or switch box motors do not use magnetos ?--------Well the early Johnson electronic ignitions were called ----" Magflash ignition "---Short for magneto flash I think.

 

[GA_Boater]

?-------CDI or switch box motors do not use magnetos ?--------Well the early Johnson electronic ignitions were called ----" Magflash ignition "---Short for magneto flash I think.

Capacitor-discharge ignition is how Johnson itself describes Magflash ignition. Just another marketing name for CDI - No magneto.

 

[flyingscott]

You need to do a compression testand an open air spark test. Was the motor ever overheated.

 

[racerone]

I suppose one could use the dictionary or even ---Google ---To find the definition of a ------Magneto.

 

[dthx]

I understand your point and appreciate your dig, raceone....
Back at ya, though.....Magneto, according to Google is a fictional character in the x-men series.
BTW...with all of your help I'll find out what's wrong with this engine.....and I really appreciate the resource and help.
The compression on the top cyl reads 120 psig
The compression on the bottom cyl reads 115+ psig
The engine has never been overheated
I've ordered a spark tester online and am waiting for it.

 

[racerone]

Good luck with the project

 

[Sylva-Ranger]

If a Merc 25 have good ignition on both cylinders and still missing one cylinder, sometime this is because one of the 2 magnets Inside the flywheel is unglue and is not still in the good place.

​Usualy thats make the motor to shake well .runing only on one cylinder but have good ignition on both


​You can check whit a timing-lite on both cylinder to confirm the timing, or just check the magnets visualy or whit your fingers , they suposed to be 180 degres , when one magnets unglue, its usualy move close to the other one and stay Inside the flywheel just by the magnetic force.

​Thats make one cylinder runing ok, and the other one out of time make fire just few degres after the first but stil have fire.
​That make all the DVA tests normal
​That make the timing lite test/timing are normal on cylinder number 1 in your case.

 

[dthx]

Raceone.....thanks...can't do it without your help...
Sylva-Ranger....if that's the problem it would be the crazy......but I'll check it out, for sure.....thanks