It's just not right....

a14rgs said:
Air leak via the carb vacuum pipes? (the pipes that connect all three carbs via the brass spigots) - I had a popping and banging issue at low revs with my 1200 and found that these pipes were loose on the spigots, so drawing in air.
Replacement pipes and T-piece fitted (thanks DucatiPaddy) and normal service was resumed....
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I had that problem back in the 80s. No need for Ducati Paddy. Tube and Ts for aquariums do the job perfectly.
Paul
 
piranha-bro2 said:
I don't suppose the carbs have those removable screws into which balancing spurs can be screwed, and one of the screws is missing? The issue just reeks of air getting in at high vacuum (= low revs and low slide position).
Click to expand...
Would not the spraying with carb cleaner show this problem up? On the recent Breganze trip I found out that the pipe between the manifolds was perished and off, it was somewhat more apparent than just running rough!
 
When this symptom showed up on me, I used the timing light to visually see if sparking consistently. It wasn't! I could 'see' the misfire on number three. Since I had recently replaced HT wires, I switched one over to three, Then number one was doing it! Put my original copper core wires and caps back on. Perfect! How can a new plug wire be faulty? A year later, similar behavior. Clogged idle jet.
 
KERMIT1200 said:
If timing is not correct, the mixture screws will not any or no effect. Considering the amount of work carried out on the carbs, I'd check the timing. Even check that the right coil is connected to right channel. Are the cams timed correctly, could they be a tooth out?

Andy
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The timing has been checked twice, it is correct. The correct coils are connected to the correct plug. I haven't taken the rocker cover off to check the cam timing, but I am really anal about that sort of thing when I did the valve clearances, I would be very surprised if that is the issue.
I will check though.
 
piranha-bro2 said:
I don't suppose the carbs have those removable screws into which balancing spurs can be screwed, and one of the screws is missing? The issue just reeks of air getting in at high vacuum (= low revs and low slide position).
Click to expand...
Nope, they are all present and correct.
I agree it seems to be an air issue
 
a14rgs said:
Air leak via the carb vacuum pipes? (the pipes that connect all three carbs via the brass spigots) - I had a popping and banging issue at low revs with my 1200 and found that these pipes were loose on the spigots, so drawing in air.
Replacement pipes and T-piece fitted (thanks DucatiPaddy) and normal service was resumed....
Click to expand...
Checked this over the weekend, I thought it was a promising idea, but nope.....
 
3CBRG said:
When this symptom showed up on me, I used the timing light to visually see if sparking consistently. It wasn't! I could 'see' the misfire on number three. Since I had recently replaced HT wires, I switched one over to three, Then number one was doing it! Put my original copper core wires and caps back on. Perfect! How can a new plug wire be faulty? A year later, similar behavior. Clogged idle jet.
Click to expand...
Hhhhmmmm....I will check this out
 
Tippie said:
Would not the spraying with carb cleaner show this problem up? On the recent Breganze trip I found out that the pipe between the manifolds was perished and off, it was somewhat more apparent than just running rough!
Click to expand...
I have drowned the carbs in carb cleaner.....tried again today...no change in engine speed at all.
 
I have an acquaintance who is a very experienced motorcycle mechanic and he specialised in older bikes, he is now retired but I talked to him today and he is willing to have a look at it for me...hopefully he will be able to help.
 
Long shot department - two suggestions
1. The atomiser jet is available in different lengths - do you have the correct type (AB)? Right hand item in the photo
2. The needle float valve on my Corsa saw me limp home from Italy many years ago on 2 cylinders. The indent in the brass/rubber tipped part that retains the spring loaded plunger was insufficient to retain the plunger. So float height completely gone to pot.

DR AR AB atomisers.jpg
 
Re5Guy said:
The timing has been checked twice, it is correct. The correct coils are connected to the correct plug. I haven't taken the rocker cover off to check the cam timing, but I am really anal about that sort of thing when I did the valve clearances, I would be very surprised if that is the issue.
I will check though.
Click to expand...
Timing and consistent sparking two different tests. Same tool. It wasn't until I clamped one by one, all three wires that I noticed the issue, in my case number three.
 
Ok, update time.
There is good news and bad news. The good news is that it is fixed and is going well.
The bad news is that I have no idea why.
Yesterday, before taking the bike up to the mechanic I stripped down the carbs again. Couldn't find anything amiss. Everything looked fine. So I reassembled it all and left it at that.
Today when I rode it up to the mechanic it went fine, he checked it over and it WAS fine. I could now adjust the rpms using the air screws properly and it wasn't misbehaving.
So thanks to all the helpful suggestions, I'm thinking I must have done something when I had the carbs apart, but no idea what unfortunately.

And here's a picture of the bike

cheers, Tony
 

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Well, that IS good news ... and bad news :cool: - we all wanted to know how the story ends! You'd have to assume it was the carburation - but who knows what?!
 
Bikes often behave themselves once a proper mechanic approaches them, sly bastards. A bit like the kid too sick to go to school suddenly gets better then the evil tasting medicine gets taken out of the cupboard.
 
Tippie said:
Bikes often behave themselves once a proper mechanic approaches them, sly bastards. A bit like the kid too sick to go to school suddenly gets better then the evil tasting medicine gets taken out of the cupboard.
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Very true....bastards indeed.
I felt a bit of an idiot though, taking the time out of his day for no reason...he was very gracious though. Then we talked for ages about bikes, like you do! :LOL:
 
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