It's been a while since I've visited the forum and after quickly perusing the recents posts I am going to remind myself to do so more often.

My 87 F1B, along with her sisters, was dry docked for the winter with Stabil in her tank and carbs, and safely tucked in my warm, dry garage here in Northern California.

Once spring sprang she was the first motorcycle I took for a ride, and both times I've done so I have had some drama. The motorcycle runs very well for a while, but then seems to run on only one cylinder. My first thought was was that it was out of fuel, and after sitting for an hour or so and topping off the tank, she ran properly again.

Last weekend I took her for a ride and the same symptom occurred-ran well for a while, then started running very poorly, dying if I didn't whip the throttle a lot, as if only hitting on one cylinder. It's either spark or fuel, and as I've had the carbs off and cleaned them I'm starting to think it's either junk in the tank (not terribly likely) or perhaps a coil that is intermittent. I seem to recall a problem with coils on these machines and am curious if anyone has any advice regarding debugging this problem. It's kind of a hard one to diagnose when it occurs. I have not yet removed the fairing and removed spark plugs to see what they're doing but I will do. I just wanted to prime the discussion before I do so, in the hopes that the collective wisdom here may shed some light on the best path to resolution. The F1 remains my favorite Ducati to ride.

ciao!
-tj in los gatos

Hello, I use the simultaneous translator to understand your English, and the translations are not very true, but I have understood, that your bike, if you stand still for a while, she then proceeds normally.

I believe that is not dependent on current.

I think there is a tap of the dirty tank, or a passage from the carburetor is clogged.

You Invert the carburetors, and see if the problem moves to the other cylinder.

You have to do one house at a time, you will not have to disassemble most things together, if you have a go at a time, you will find the problem.

I hope that the translator has done a great job.

Ciao. Carlo

Ciao Carlo,

Grazie per aver dedicato del tempo a rispondere, e per prendersi il disturbo di usare il traduttore. Io sto facendo lo stesso e spero che la mia risposta ha un senso. Sono d'accordo con te e penso che sia più probabile un problema di consegna del combustibile. Io prenderò il serbatoio del gas off e scarico per assicurarsi che il rubinetto non è intasato. Se non trovo lo sporco in essa io controllerò i carburatori. Io non sono sicuro se è possibile scambiarle come lei suggerisce, ma se si tratta di una opzione cercherò quello.

Grazie!
-tj

Hello Carlo,

Thank you for taking the time to respond, and for going to the trouble to use the translator. I am doing the same and hope that my response makes sense. I agree with you and think that it is most likely a fuel delivery problem. I will take the gas tank off and drain it to make sure that the tap is not clogged. If I don't find any dirt in it I will check the carburettors. I'm not sure if it's possible to swap them as you suggest but if it's an option I will try that.

Thank you!
-tj

Blocked fuel tank breather?

The little round nylon filters under the fuel inlet banjos can sometimes get a little clogged up due to the high content of alcohol in gas now, and might be restricting fuel flow. Did you happen to blow them out when you cleaned the carbs?
Bill

Good ideas both, guys. I'll check the breather and the filters.

Ciao!
-tj in los gatos

Hi - had a similar problem some time ago. In my case it turned out to be 1 float needle that was hanging up causing intermittent running on one. Embarrasing - lots of noise (Verlicchi) but no go! Check is to stop engine when it happens and remove float bowl bottom nuts (and bowl) in turn and check how much fuel comes out - should be about the same for each one. New needle assemblies cured the problem for me. Probably is caused by modern fuel - hope this helps.

Hey guys, thanks for the suggestions. It turned out that it was the fuel tank vent! It was amazingly simple to diagnose, and even simpler to fix. I started draining the tank in to a fuel bottle and had the fuel line for the rear carb hanging the bottle. After a few minutes I went to check the progress and noticed that fuel had stopped flowing. I removed the fuel cap and voila!, it started gushing out again. I then put the fuel cap back on, and it eventually slowed again. This time I removed the fuel tank vent hose from the clip on and again, fuel started flowing. What's curious is that since I don't have my original rearview mirrors, the previous owner installed a bar end mirror on the left clip on on my motorcycle. This effectively seals the clip on, creating a vacuum lock on the side which has the vent tube. What doesn't make sense though, is that from the factory they had plugs in each clip on, which I assume would have had the same effect. In any event, I'm still looking for the proper rearview mirrors for my F1, so I've removed the bar end mirror for now. Like they say on the race track, "whatsa behind you she no matter."

She's now running beautifully and even idles well (for an F1) so I'm going to go take her for a Saturday morning ride.

Ciao!
-tj in los gatos

The end cap on the left side has a hole drilled in it for venting. Same thing happened (would stop running as if out of gas, open the cap --- woosh---off we go again) to my F1 many years ago, and I went to an in-line 900SS vent on the tube. MikeV

I'm glad you solved your problem. ciao

for me it was a pleasure