lower bank does not fire up

[franco]

Hi boys;
before I go nuts, help me.

Rebuilded engine. All 4 plugs give lively spark.
Once trying the real thing, upper bank is good as it should be.
Lower bank cold as ice. Good ohm readings from coil. Then once at a time changed plugs, wires, coils, still lower bank is dead.

What do you think?

[silverstrom]

Flywheel - pickup coil gap is too large?

[franco]

But upper bank seems perfect. Could it be?

[Motolli]

Try to reduce gap to around 0.7 mm.
Check the grounding of the lower coil. The minus terminal can be connected directly to the frame.
Try to connect the plus wire from the top coil to the bottom coil.just to check if on your bottom plus line is something wrong. This would indicate a broken wire or In worst case a failed CDI

[silverstrom]

This sounds like your problem. This was 3 weeks ago. CDI was bad.

https://www.rzrd500.com/500phpBB3/viewt ... =3&t=16372

[franco]

Check the grounding of the lower coil. The minus terminal can be connected directly to the frame.
Try to connect the plus wire from the top coil to the bottom coil.just to check if on your bottom plus line is something wrong. This would indicate a broken wire or In worst case a failed CDI

Done that, unfortunately nothing changed.

[franco]

Flywheel - pickup coil gap is too large?

Silly question of mine, is it possible change gap? It looks very firm and solid to me.

[Motolli]

Hey franco
If you did connect the plus wire of the bottom coil ( with wire extension ) to the bottom coil, and it didn’t fire the bottom cylinders, then it can be a fouling coil. Change the coils from top to bottom!

[franco]

Ok, I'll swap them, general thanks for advices, mates.
Anyway I had checked readings, they were good, and put another coil (with good redings too) from another 500.
But I will try swapping upper-lower.

[phildu31]

Don't bother with gap.
There is only one which is used for all 4 cylinders.
This problem only result from a defective CDI ou lower coil.
If connections are good and lower coil ohm readings in acceptable values then ... it only leaves the CDI unfortunately.

[franco]

Latest try:
I left upper and lower coil linked to their original harness places,
but reversed plug cables routes: upper coil now feeded lower cylinders and viceversa.
Result... again upper cylinders roaring and lower cyls silent..

This should say CDI is not guilty, as if it was, I should have now lower bank firing. I think.

[Darrell]

I assume this is the first attempt to run your rebuilt engine.

Given the results of your most recent attempt I would think you now must look beyond the ignition system. Engines need three things to run, compression, fuel, and spark. You now know yours has spark, so either those cylinders lack compression or fuel. I'd carefully check the carburetors next. Perhaps pull the plugs and squirt a small amount of premixed fuel into each cylinder and see if they fire.

[franco]

Darrell, I do agree with your overall approach.
About fuel section, I will try syringing fuel, or another set of carburetors.

[1601pete]

Have you confirmed you have a good spark on all 4 cylinders with the “same” spark plug or the plug destined for each individual cylinder?

[vma500]

Start with disconnecting all lights etc...
Also pv module off,servo off
Run it only with the cdi ,instal an earth wire from the battery directly to the frame
Check the rectifier is earthed too

See what happens then,any improvement?