Ugh- Ignition PROBLEM

I know that you are good at engines. I am way curious what it is.... Was there spark?

Is there an intermittent power issue? Maybe there is a wire that cuts, shorts or overheats?

Ahhhhh!

I haven't sat down and played with it yet. I'm going away for the weekend, I'll get to it sometime early next week I'm hoping.

I had the same problem on my four-banger. The cylinder in question was running way too rich due to a leaky diaphragm in the vacuum petcock.

... Rich meant it would only fire at high rpm, and the gas mileage was poor.

Keep an eye on the plugs.

Sandy wrote:

Erik...what's the scoup on your CARBS bud?
Maybe it ISN'T ignition,because yes,you're right...2 and 3 ARE fireing off the same coil.(they better be wired up that way,anyway)

Have you had the carbs apart?
How long has the bike sat with fuel in the bowls?

Someone on here said that the coils have to fire both spark plugs at the same time or else the won't fire at all. Is that true??

Becker wrote:

Someone on here said that the coils have to fire both spark plugs at the same time or else the won't fire at all. Is that true??

Yes, basically that is true. In order for spark to occur at one of the pair, there should be spark at the other one of the pair. The only exception is if the spark is leaking to the frame or engine through the wire or through the coil or inside the coil.

Test the resistance between each plug cap and the engine case.

UPDATE:



I went over all connections and checked them for proper clips and made sure then were clean and together correctly. I then replaced the battery like was suggest to...started right up using the electric starter. Runs well! So, cylinder 1, 3 & 4 are running perfect! Cylinder 2 still won't fire. I pulled the plug out and tested it, it had a fat blue spark. Which tells me it's getting spark. Soooo, it leads me to a carb problem? Not getting fuel or something? Not quite sure, I'm going to tear into it when I get time. I'm just digging away at this project one piece at a time.


Also, cylinder 1's CARB keeps bacfiring out of the air filter. Like a "puff" backfire, not so much of a flame 'boom'. I don't know, it's hard to explain. LOL

Thanks,

-Erik

If not already done, would do compression
test (at least on on cyl#2) and especially
check valve clearances on #2.

As known, acceptable cold compression psi
may be lost at normal operating temp.
This can happen when a too tight valve
is barely closing enough when cold but
fails to completely close when warm.

Good Luck!