80HP 2-Stroke Ignition Issues

[99yam40]

Do think that a CDI assembly can be tricked by using say a 90 volt battery to charge a capacitor and then using a magnet to trick the pulser coil into firing the spark plugs?

never thought about it, or heard of any one doing that

[Nuclear-Inc]

I went ahead and, purchased a new CDI with superseded part number. Considering both original and replacement CPS tested good. I appreciate everyone's opinion on the matter. However, I'm really tired of going over engine. Hopefully it will correct the issues. The CPS, Pulser coil, stator. There can't be anything else wrong. I also noted that the engine ides at 1900-2000 rpms and, does not settle down after warming up. Before this all started it will idle at 1200-1300 and settle down to 750-850 after warming up.

[boscoe99]

never thought about it, or heard of any one doing that

Neither have I. I just thought of it as a way to test the CDI.

Years ago I used a magnet to trick a four stroke to fire the spark plugs. But it was a transistorized ignition system.

[ausnoelm]

I can't say rooting around with 90v batteries and magnets would be my ideal way of testing electronic components, checking inputs and outputs is the recommended method, it's easy and it works. Testing and playing with parts not associated with the fault is also not recommended, or you can be chasing self induced faults, you didn't mention the high idle before by the way. Read your very first post carefully, why would you want to "trick" the pulser coil?

[99yam40]

I went ahead and, purchased a new CDI with superseded part number. Considering both original and replacement CPS tested good. I appreciate everyone's opinion on the matter. However, I'm really tired of going over engine. Hopefully it will correct the issues. The CPS, Pulser coil, stator. There can't be anything else wrong. I also noted that the engine ides at 1900-2000 rpms and, does not settle down after warming up. Before this all started it will idle at 1200-1300 and settle down to 750-850 after warming up.

Have you checked to see what the timing is doing?
I have a C40, and the timing was off at idle when I set it according to manual.( causing idle problems)
ended up having to replace the CDI to fix that.
at start up timing is adjusted by the CDI, and when a temp switch tells the CDI when the motor has warmed up, adjusting the timing is set to normal lowering the RPMs.( at least that is what mine does)
But my C40 has 3 pulser coils con*****ing spark and I did not have any problems with missing spark, just a timing problem

[99yam40]

Neither have I. I just thought of it as a way to test the CDI.

Years ago I used a magnet to trick a four stroke to fire the spark plugs. But it was a transistorized ignition system.

I would think that someone could create a device to mimic what is needed electronically to test the CDI,
but there would be a need for a special device for each motor CDI or at least a lot of them since a lot are so different

[boscoe99]

I can't say rooting around with 90v batteries and magnets would be my ideal way of testing electronic components, checking inputs and outputs is the recommended method, it's easy and it works. Testing and playing with parts not associated with the fault is also not recommended, or you can be chasing self induced faults, you didn't mention the high idle before by the way. Read your very first post carefully, why would you want to "trick" the pulser coil?

And I would agree with you. But if there was a simple way to charge the capacitors in a CDI box, and then get those capacitors to discharge into an ignition coil, causing the plugs to fire, that might give one a good reason not to rush out and buy a replacement CDI box before thoroughly testing the rest of the motor. As all too many try and do. Only adding to there inventory of unneeded perfectly good parts.

[Nuclear-Inc]

Quick update!

I received and installed new OEM Yamaha CDI. However, the engine cranks and, every now and then it will sputter for half a second. I have checked every connection and, ground on the engine. I will have too double check it later this evening or tomorrow morning. I connected all coil wires correctly. This engine was running a few days ago so, it's not a fuel or timing issue. Maybe I got a defective CDI?

[boscoe99]

I suspect that you have two perfectly good CDI boxes. Happens all of the time.

[Nuclear-Inc]

I suspect that you have two perfectly good CDI boxes. Happens all of the time.

Engine should start regardless of my previous issue. This engine doesn’t spark #2 during starting from the factory. The engine momentarily sputters for a split second and even backfired on me while cranking. It”s trying to start, Fuel and compression is good. That leaves me with spark. When I get home I will verify spark #1, 3. It’s acting as if they timing is off. I will also have to verify CDI coil leads. There is a small possibility they were labeled wrong with cylinder number. I will get back with you guys.

[ausnoelm]

Seems like as it stands, you have two working CDI units, have not solved the original fault, and now have a new self inflicted fault.....time to step back, take couple of deep breaths and trouble shoot methodically and properly. It's a very simple engine, you have said yourself you know how the spark on #2 is different to the spark on 1&3, don't chase ghosts and just buy parts.

[99yam40]

Taking peak voltage readings if spark is missing on any cylinders would help figure out where the problem is.
timing light will show is and where spark is hitting on each plug

[Nuclear-Inc]

Hey everyone,

I went ahead and, loosened up everything to check out all the wiring. Found the culprit! The CDI ground wire was not connected. I guess during assembly I mistook it for the electrical bracket ground cable. The lower screw takes both CDI/Electrical bracket ground cables. The engine now fires on all three and idles perfect. Hopefully this updated CDI PN will give me another 20 years of service. I would like to thank everyone for their assistance.

[TownsendsFJR1300]

Thanks for the update and congrates!

[99yam40]

Good to hear you got it running properly, and the new CDI was not a waist of money