No spark??

[Hell on Wheels]

Hey everyone,
I reassembled my engine and I'm trying to get the thing started. I have a worn spark plug wire which was grounding to the frame at first. Replaced it and the engine doesn't fire. I'm a bit lost at this point.

Has anyone connected a dedicated wire to the spark plug base to assist in grounding? The head seems anodized which shouldn't affect anything, right? Is it possible the plug is being blown out from the raised compression it's now facing vs stock?

 

[junglepig]

No, there should be no problem at all with grounding through your plug threads. That's going to be a good connection.

 

[Hell on Wheels]

No, there should be no problem at all with grounding through your plug threads. That's going to be a good connection.

I think I'm just going to get a new plug and clean the cdi coil for better grounding. I don't know why it will ground to the frame but not the plug...

 

[junglepig]

I think I'm just going to get a new plug and clean the cdi coil for better grounding. I don't know why it will ground to the frame but not the plug...

Assuming the stock style magneto/CDI ignition system:

The newer magneto stator coils have a black jumper from the bottom tab (black wire) of the coil to the core laminations. Check that this black wire is grounded. If you have a meter, check for close to zero ohms between your black wire and your engine/cylinder head/plug base.
And your magneto coil should measure around 300-400 ohms (between blue and black wires). Mine is 355 ohms.

Also, check your spark coil secondary winding. You should have about 6000 ohms between the plug wire screw at the CDI and the black wire of the CDI. Mine is 6.3K.
You should have the same from the spark plug terminal to anywhere on the engine if your wire and cap are non-resistor and your secondary is good.
If you have resistor on the HV side, add that resistance in. This will check that everything is ready to fire on the secondary circuit.

The CDI can be partly checked as well. Between Blue and Black it will behave as if there is a capacitor across it, because there is. So initially it will read low resistance that increases all the way up to an open circuit as the cap charges up from your meter.

Hope that helps.

Here's and earlier discussion I had on this.

 

[Member 28982]

Also you can peddle your bike and release the clutch and grab the head of the spark plug wire and if you don't get shocked it's most likely your CDI because these Magneto's rarely malfunction because I've got three for sale and every time it has been the CDI.
You should have .321 or is it 3.21ohms or around there depending on the setting of your multimeter..
If it's open it'll read OL, If it's closed you'll get a reading....
Forgot what CDI suppose to be...

 

[Member 28982]

Wire's should be blue on green and black on yellow

 

[Hell on Wheels]

I think I'm not having a cdi or magneto problem. Or coil. I hooked up a ground wire to the base of the spark plug, got a resistor spark plug wire, ditched it for alligator clip wires, and solved short circuiting, and no firing. New plug too. I think the high compression (using CDHpower cnc head with 0.8mm squish) is blowing the spark out because sparks jump any gap smaller than 1.5cm but it doesn't fire the plug in the engine.

Anyone know a higher powered magnet or coil? I already have the magnet coil with extra windings but stock magnet. Bbr stage 1 coil/cdi unit.

Or I don't have proper crank case compression. Anyway to test that? I think my previous engine had oil pooling at the bottom of the crankcase which raised compression a bit since the added area from the Reed to the piston lowered it too. And Fred's machining took alot off the flywheel. Don't know if he stuffs the crankcase.

 

[junglepig]

What makes you think you aren't getting spark?

 

[Hell on Wheels]

What makes you think you aren't getting spark?

No change in exhaust/intake tone with or without wire connected. I also tried starting fluid and choking.

 

[Street Ryderz]

I think I'm not having a cdi or magneto problem. Or coil. I hooked up a ground wire to the base of the spark plug, got a resistor spark plug wire, ditched it for alligator clip wires, and solved short circuiting, and no firing. New plug too. I think the high compression (using CDHpower cnc head with 0.8mm squish) is blowing the spark out because sparks jump any gap smaller than 1.5cm but it doesn't fire the plug in the engine.

Anyone know a higher powered magnet or coil? I already have the magnet coil with extra windings but stock magnet. Bbr stage 1 coil/cdi unit.

Or I don't have proper crank case compression. Anyway to test that? I think my previous engine had oil pooling at the bottom of the crankcase which raised compression a bit since the added area from the Reed to the piston lowered it too. And Fred's machining took alot off the flywheel. Don't know if he stuffs the crankcase.

I think the high compression (using CDHpower cnc head with 0.8mm squish) is blowing the spark out because sparks jump any gap smaller than 1.5cm but it doesn't fire the plug in the engine. It's not the comp from head it's your cdi,I run .7 squish with a small chamber (very high comp) and it doesn't blow out the spark,when the cdi is bad it can show spark outside the cylinder but not fire under compression. this happens alot to many users not a big deal.