Ducati only running on one cylinder

HardDrive · 01-12-2010, 03:03 PM

Gee, you think this might be the problem?

Its seems the previous owner was not the maintenance fanatic he claimed to be.

cstreit · cstreit's Garage

I see your problem. That's a spark plug, not a cylinder.

Did his own valve adjusts maybe?

Chocaholic · 01-12-2010, 04:05 PM

That's a Ducati safety feature.

jwasbury · 01-12-2010, 04:45 PM

Are both plugs fouled like that? Could be a symptom of a different problem.

holtjv · 01-12-2010, 04:53 PM

Haven't you always wanted a big red (yellow, right?) thumper?

HardDrive · 01-12-2010, 09:43 PM

Quote:

Originally Posted by jwasbury

Are both plugs fouled like that? Could be a symptom of a different problem.

Unless I'm reading the plugs wrong, its running rich. I'm going to change the air filter, check the choke cable, then go after the carbs. Might just have the air/fuel mix off. The carbs were rebuilt recently, but god knows what the previous owner did.

Jeff Higgins · 05:54 AM

I'll actually go out on a limb and say that plug looks fine to me. It's not the problem.

Air-cooled, carbureted bikes need to run a little fat. Most will do so when operated at less than WOT, balls-to-the-wall riding, just so they don't lean out too much when you are riding in that mode. I think a lot of guys get used to seeing pristine, light ash colored plugs common to modern fuel injected motors that do a much better job of controling A/F accross the full range of throttle positions and loads, and assume all plugs need to look like that.

Well, they don't. Carb's just can't provide the accross the range mixture control that EFI can provide. There are rich spots and leans spots. The lean spots drive the tuning. In other words, the leanest condition cannot be so lean as to damage the motor. Everywhere else in the range just gets richer from there.

I doubt the carb's are the problem, jetting or otherwise. They don't operate in an "on/off" mode, where the cylinder either fires or doesn't. Electrical components do that. If it still has the stock coils, I would put those at the top of my list to check. They are notorious on these bikes for taking a dump.

LeeH · 06:01 AM

I just converted my wife's M900 from a single cylinder to a twin. And I agree that I'd think that plug would fire.

In the case of our Monster the push on connecter where the power lead attaches to one of the coils was loose. The rubber boot held it mostly in place, so that cyclinder would come and go.

javadog · 01-13-2010, 05:57 AM

Air cooled carburetted bikes don't NEED to run rich, they do so at certain points because of things like carb reversion. None of my plugs look like that and I own a whole buch of carburetted crap.

I'll second the notion that you should check the ignition system but I'll also add that you should take a look at the modifications done by the previous owner(s) (any jetting changes? muffler changes?) and double check that, after the carb rebuild, the mixture was set correctly. I like to see it set with a CO meter, which is more accurate than my ear/seat-of-the-pants/whatever. You may also find that the front cylinder and rear cylinder have different tuning needs. I'd try to make sure their flows are similar.

Good luck,
JR