Monster 620 Running on One Cylinder

[E36 Pilot]

Hi guys,

Any help is appreciated. I have a 2003 620 Dark with 6800 miles. I had the 6K maintenance done by a factory Ducati dealer at 6400 miles about 2 months ago. I ride the bike sparingly, usually just once or twice a week.

This weekend, I warmed the bike up and began riding conservatively on city streets. After approximately 2 miles of riding, the engine began to sputter at low RPMs. Less than 3 minutes later, one cylinder shut down (I couldn't determine which while riding). I turned the bike off and haven't tried to restart it. Both spark plug wires are secure. What else should I check?

thanks,
Ted

[cyrus buelton]

Maybe the coil connections by the battery?


this happened to me a few years ago.

[Howie]

You will be able to determine which cylinder is misfiring by temperature.  The running cylinder will be notably hotter.  Remove the spark plug from that cylinder.  Is it wet? Black? Tan?  Are you getting spark to that cylinder?  Pull the plug wire, insert an insulated screwdriver and hold it about 1/4 inch from ground.  You should see spark when you crank the engine.

[E36 Pilot]

Thanks for the advice. I started the bike tonight and let it run for about a minute. The vertical cylinder is firing as usual. The horizontal cylinder is not running. Removing the spark plug wire from the horizontal cylinder had no effect on the idle.

Of course, I don't have the correct size deep socket.  I'll pull the plugs after I pick one up tomorrow.

Howie, just to be clear: am I pulling the plug from the running cylinder? If it is wet/black/tan, what would each suggest?

thanks again guys,
Ted

[seevtsaab]

You want to pull the plug from the misfiring cylinder.
If it's it's wet your problem isn't likely fueling (injector).

After verifying connections easy thing to do is swap plugs, unlikely a failed plug is.



If you have the same plugs as are in my M620 (NGK D8EA) you need a 18mm socket.
This is different than stock 5/8" plug socket that fits what I believe is standard DCP8RE
( I can't resistor - no resistor discrepency my bike seems to run fine)

[Howie]

As seevtsaab  said, the dead cylinder.

[Bones]

I'm thinking bad coil. check connections and maybe you can switch the coils around to see if the other cylinder then dies (dunno, can he do that?)

[DesmoDiva]

I had the same problem with the horz. cylander on my ST4 last summer.

After trying lots of different things it turned out the plug wire boot was bad.  The plug/wire was arcing through the boot wall to the engine.  It was hard to chase down because you can't see down in the plug well with the plug wire there.   

Dealer resolved the problem by wrapping the boot in electrical tape and ordering me a new plug wire.  I decided to replace both just to be safe.  I believe they were orginal with 15,000 mi on them. 

[cyrus buelton]

I'm thinking bad coil. check connections and maybe you can switch the coils around to see if the other cylinder then dies (dunno, can he do that?)

When I dropped a cylinder, that is the first thing my ducati mechanic said to do.

You can start isolating your problem there.

[darkduc7]

Maybe the coil connections by the battery?


this happened to me a few years ago.

+1 on this. my dealer didnt hook up my coil connections once and i had a hell of a time determining what the problem was. hooked up said wire, bingo. i suppose they could vibrate off too.

[cyrus buelton]

+1 on this. my dealer didnt hook up my coil connections once and i had a hell of a time determining what the problem was. hooked up said wire, bingo. i suppose they could vibrate off too.

When I started this process, one of my connections had come off.

and come to think about it, a few days before I was installing a battery tender, so must have knocked off the connection.


doh!

[E36 Pilot]

Thanks for all the great advice. I'm starting my project tonight.

[E36 Pilot]

Success!

It was actually a bad plug. I swapped plugs from each cylinder and restarted the bike. This time the rear, vertical cylinder was down. I installed two new NGK plugs and the bike came back to life immediately.

Unbelievably, the plug on the front cylinder had gone bad in about 400 miles (or maybe the shop never replaced it during service).

Anyway, thanks for the comments. So far this community has been a great resource! I hope to be around for a while.

Ted