No left spark

[arbakken]

So, since it snowed a lot, my GS500 sat there for a month. It was warm today, so I was going to drive it to it's winter hiding spot. So, I started it, and it ran fine. I rode it around, and it was great. A friend of mine wanted to take it around the block, so I said ok. He got 100yds away and it wasn't running well anymore. Some diagnosis later, I determined that the left cylinder had NO spark (pulled the plug wire, no change - then verified visually). So, I diagnosed:

Coils - ok
plug wires - ok

it seemed that something was not telling that left cylinder to fire. So I took a look at and reset the pick up gap. Then, I had spark and it ran for ~3 min before the left cylinder cut out again. I took a look at the pickup, and nothing had changed.

I don't know what to check next. It almost seems like fiddling with the pickup didn't actually help anything, it was just a fluke. But, I don't know how to test that or the ignition module. Any help ideas?

[quiktaco]

I'd say your cheapest test would be to buy some new plugs and see if the problem persists.  Or even swap the left to the right and right to left.

If you can rule out the plugs, it's probably the coil...It may seem like it's fine, but it might be on it's way out.

Can anyone confirm my post?  I'm not an expert, it's just my best guess.

[arbakken]

plugs are new, but I checked them side to side, and they are good. Coil is good also.

[Weston]

if the coils and wires are truely good then that only leaves the cdi box. How do you know that the coils are good?

[arbakken]

if the coils and wires are truely good then that only leaves the cdi box. How do you know that the coils are good?

checked them with an ohmmeter, they checked out in spec

that leaves the cdi box, and the pickups

[arbakken]

anyone? trouble shooting advice for cdi box and pickups?

[Paulcet]

For CDI box you need a special tool.  For pickups, I think they are 250-350 ohms.  Search for "signal generator".