Hi all,

after 45 min's of riding, my Paso seems to drop a cylinder. I haven't even begun to troubleshoot it yet, but it's remarkably similar to what happened to my '92 900ss.

That bike turned out to be a bad ignition module, a Kokusan bb1105. Well, I was surprised to see what appears to be the exact same ignition modules in my Paso.

The stickers and all identifying marks are gone on the modules in my Paso, but can anybody confirm that these are indeed the same? The module in my hand is from a '92 900ss.

the ignition modules on the Paso are the same, they are also BB1105.
I`ve heard of cylinder dropouts from multiple reasons from carb problems, wiring issues, bad spark plug cables, pick ups etc but have never meet anyone personlly so far that had a broken CDI unit.

G.

Well, you were right, swapping the Kokusan bb1105 modules in from a good running bike didn't cure the problem.

When the problem occurs, the idle is very low, like 900 rpm. Normally this bike is set to idle at 1200rpm.

Unplugging either spark plug lowers the idle even further, maybe to 700. Even at this low idle, an inductive timing light shows spark on both plug lines. So it doesn't seem to be dropping a cylinder electrically after all.

The problem comes and goes. Several times it did it after running fine for almost an hour. Today it had the problem from initial startup, but then after sitting in the driveway for an hour, it started and ran fine.



Any suggestions?

Wow
I would check the fuel tank breather and the pump and filters ( dont forget the strainer at the carb ).disconnect and reconnect all harness plugs ( some times this scraping motion can clear a bit of oxide off a bad connection ). You say that an inductive pick up indicates spark on both pots ..... is the timimg consistant and correct and does it advance as revs rise ? The fact that you have spark ( assuming that its all good ) on both pots , and that removing either plug lead slows idle , makes me think that whatever is causing the problem is common to both pots , like a fuel or power supply, or a bad earth somewhere , or the pickup coils , which may be fine when cold but can play merry hell when hot if faulty.
good luck

Intermittent ignition problems can be very hard to sort out. There is a very well written pdf here on checking everything.

Don't forget those ignition wires,a common source of intermittent failures. And pull those plugs and check for broken insulators.

http://www.800-airwolf.com/pdffiles/ART ... t%2058.pdf

Nice, thx f sharing!

Oh, and for all those making fun of my mono-Paso, (AHEM, cough cough, FasterDammit, cough!). Good news. Just rode it 30 miles without a hiccup. Not sure what cured it. I checked the air gap on the pickups (it was fine, but the gasket tore and took an extra 2 hours to make a new one), changed the fuel filter, cut back the spark plug wires, new spark plugs, chased a bunch of air bubbles out of my fuel lines (my Paso doesn't use a fuel pump, it's a gravity feed system to a set of Dell'Orto's)....

Not sure what the Ducati Fashion Police would think about driving around with no fairings and an inductive timing light duct-taped to the gas tank....

(not even sure it's fixed, but the problem had been rearing its head long before this many miles...)