Dt20, dt25, dt28

[fantasy20]

Hello, I have a 1980's DT28 with no spark.

What I cannot understand is that although it has two cylinders and two HT leads (coming from one coil unit) there is only one wire coming from the CDI unit.
How is the spark directed to the correct cylinder? Or do they both spark at the same time?
I have the engine in my garage without the ignition switch.
Am I correct in assuming that if I crank the engine using the electric starter there should be a spark?

I do have the manual and wiring diagrams.

Any help would be most welcome

[Solarman]

I don't think you would get any spark without the wiring harness connected and intact (proper switches, wires energized). You might be able to jumper the wires needed to start the motor using the wiring diagram, but I can't tell you how to do it.

Good luck.

[fantasy20]

dt28 vCDI

Hello, can anyone tell me what the wires from the CDI are?
In particular the GREEN one - does it need to be connected to 12 volt?

[Dan Crick]

Hello, I have a 1980's DT28 with no spark.

What I cannot understand is that although it has two cylinders and two HT leads (coming from one coil unit) there is only one wire coming from the CDI unit.
How is the spark directed to the correct cylinder? Or do they both spark at the same time?
I have the engine in my garage without the ignition switch.
Am I correct in assuming that if I crank the engine using the electric starter there should be a spark?

I do have the manual and wiring diagrams.

Any help would be most welcome

I am having similar problems. Is there anyway you could post or email me copy of wireing schematic? Please

[saab 340]

Hello, I have a 1980's DT28 with no spark.

What I cannot understand is that although it has two cylinders and two HT leads (coming from one coil unit) there is only one wire coming from the CDI unit.
How is the spark directed to the correct cylinder? Or do they both spark at the same time?
I have the engine in my garage without the ignition switch.
Am I correct in assuming that if I crank the engine using the electric starter there should be a spark?

I do have the manual and wiring diagrams.

Any help would be most welcome

Hi!
i have an old DT28 too,it sparks both plugs at the same time,only one cylinder fires at ignition pulse because that piston is in 'compression',and the other just has reached the llowest point of exhaust mode,therefore the lowest cylinder has no compression to permit ignition,even though there will be a spark from the plug.
Yes,you should get a spark from both plugs at the same time when using the elecric starter,actually a big fat blue spark due to the high rotation speed of the magnets in the flywheel.

[mattism]

Hello, can anyone tell me what the wires from the CDI are?
In particular the GREEN one - does it need to be connected to 12 volt?

I have the same problem as you. I belive that the green one is the trigger for the spark to go off. You have two wires from the magnetic coil. It sends 12 v i think to drive the cdi. At the same time it is used as a trigger(the green one), thats why you have two wires going into the cdi from the one coming from the magnetic coil. I belive my cdi has a fault. Expensive to replace.

[mattism]

Hello, I have a 1980's DT28 with no spark.

What I cannot understand is that although it has two cylinders and two HT leads (coming from one coil unit) there is only one wire coming from the CDI unit.
How is the spark directed to the correct cylinder? Or do they both spark at the same time?
I have the engine in my garage without the ignition switch.
Am I correct in assuming that if I crank the engine using the electric starter there should be a spark?

I do have the manual and wiring diagrams.

Any help would be most welcome

Yes it would start. The ignition runs the start engine and it has a ground loop to the gear setting and a ground to kill the engine. If you disconnect the ignition you remove the kill ground, thats the only thing having to do with the engine running. If you bypass the starter you should start without the ignition connected. But you have to ground the green wire on the cdi to kill the engine.

[mattism]

I have now bought a universal 2 stroke dc cdi box(4 pin) for 10$ to replace the original and it works! Cheep fix!

Mattism