No Spark on #1 & #4 - Maxim 650

[aircap]

Hi:

The other night I was cruisin' along on my '82 Yamaha Maxim 650 when suddenly my bike started running very badly. I thought at first maybe I was dealing with a new angle on my previous fuel starvation issue, but discovered that the #1 and #4 cylinders (the outboard jugs) were getting little or no spark.

Those plugs are fired by the left-side coil, which I removed and had tested today, only to find that it's not the culprit. Any ideas? The plugs look great, by the way.

Any help is MOST appreciated.

Thanks!
Carmody
Wichita, Kansas USA
Air Capital of the World

[TechTMW]

How about testing the resistance on the HT Leads and the Plug Caps?

Also - some coils develop cracks that only show when the bike is hot and the parts expand ... so don't rule out the coil yet.

[aircap]

Oh, I forgot to mention...I don't have like an ohmmeter or electrical tester doohickey. And I'm not sure what the HT leads are, either...the wires going into the coil?

Sorry. I appreciate any suggestions as to where to look next.

Thanks again,
Carmody

[TechTMW]

HT Leads are the spark plug wires.

If you are having an electrical problem after the coil on only 2 cyls, it's either the coil, HT leads, or caps. I'd take the bike in and have them test all 3 ... and have them test it once the bike has reached running temps.

A cheap multimeter's only about $25 ... probably half the cost of one visit to the garage ... might want to consider it.

[aircap]

So...how do I know it's after the coil? Where does the juice come from before it gets to the coil? What triggers the coil to send spark to the plugs? I've never had an ignition setup like this before, where the coil goes directly to the spark plugs. A little background on how this works would be very helpful to me...anybody know where I might read more about this type of ignition system online?

Thanks.

Carmody