1989 900 Supersport running on one cylinder

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TheDuctor
Posts: 36
Joined: Wed May 01, 2013 7:43 pm
model: 900 SS
year: 1990
Location: UK

1989 900 Supersport running on one cylinder

Post by TheDuctor »

Hi guys, not been on for a long time as I didnt get muchuse out of the bike last year unfortunately. I've just got it out from winter lay up and I have started the riding season with a problem. The bike started fine and ran fine up until I stopped about 2 miles up the road for petrol. When I restarted it though it only ran on one cylinder. I got it home and put my extensive knowledge, know how and tooling abilities to work. After hours, ok it seemed like hours, I had exhausted my knowledge, know how and tooling abilities. Through swapping plugs and ht leads over I narrowed the problem to the front, or horizontal cylinder. I put that spark plug in the rear cylinder and that ran ok. I did notice that the wire in the pic from the back of the rectifier(?) was totally loose and not to mention the fuel line joint!! Could either be the cause?
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bmw851
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model: other
year: 1988
Location: The Blue Mountains, NSW, Australia

Re: 1989 900 Supersport running on one cylinder

Post by bmw851 »

Nah, none of those things shouldn't make it run on one, reckon the Flux Capacitor is stuffed.................... :fart:
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TheDuctor
Posts: 36
Joined: Wed May 01, 2013 7:43 pm
model: 900 SS
year: 1990
Location: UK

Re: 1989 900 Supersport running on one cylinder

Post by TheDuctor »

Yeah, the capacitor definitely seems to be fluxed. Well and truly fluxed!
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higgy
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Re: 1989 900 Supersport running on one cylinder

Post by higgy »

better check the muffler bearings and the constant entropy seals while you are at it, they do tend to act up when ignored :beer: :beer:
Ducati,making mechanics out of riders since 1946
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Re: 1989 900 Supersport running on one cylinder

Post by Mc tool »

Geeeeze and I thought I was bad at the smart arsed replies :D
Ductor you gotta sort the ..................................wait a minute.....are you taking the piss :D :mad: :D ( shit ! I nearly fell into that ! ) ...........yeah , make sure you didn't put the petrol in upside down :-P
I wish I was young again............Id be heaps smarter than last time
TheDuctor
Posts: 36
Joined: Wed May 01, 2013 7:43 pm
model: 900 SS
year: 1990
Location: UK

Re: 1989 900 Supersport running on one cylinder

Post by TheDuctor »

Thanks guys :banghead: :lol:

Anyone got any real suggestions though :D
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bmw851
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year: 1988
Location: The Blue Mountains, NSW, Australia

Re: 1989 900 Supersport running on one cylinder

Post by bmw851 »

OK with a heavy Irish accent alay the I.T. Crowd

Have you tried turning it off and on :drunk:

Himself
So long, and thanks for all the fish...............

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TheDuctor
Posts: 36
Joined: Wed May 01, 2013 7:43 pm
model: 900 SS
year: 1990
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Re: 1989 900 Supersport running on one cylinder

Post by TheDuctor »

I'm going outside to stick myself in the ear with a blunt pen
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bmw851
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Joined: Tue Mar 13, 2012 9:02 am
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year: 1988
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Re: 1989 900 Supersport running on one cylinder

Post by bmw851 »

Is that like cutting someone's heart out with a spoon, ok that that does it, no more merciful beheading's, no more scraps for the leper's and Christmas is cancelled.

No pleasing some some people, but that's what he said........................ :truck:
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paso750
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Re: 1989 900 Supersport running on one cylinder

Post by paso750 »

assuming you still have the original Weber carb that broken Y piece is the split to the carb and the return line. You should have fuel everywhere.
What`s connected to that blue wire only you can check.

When you`re finished poking yourself in the ear with a pen swap the CDI units. If the non running cylinder remains the same swap the coils. If that doesn`t change anything measure the pickups to verify that no wire might be broken.
Then measure the voltage at the coils at ignition on and engine running. If it`s lower than the actual battery voltage do the wiring mod (see FAQs).
You should then have spark on both cylinders (or if one coil, HT lead, spark plug or CDI unit is defective at least swapping the parts from the horizontal to vertical cylinder then should make the other cylinder run). If every ignition part is ruled out as possible source of the problem you should check carb synchronization.

G.
TheDuctor
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Joined: Wed May 01, 2013 7:43 pm
model: 900 SS
year: 1990
Location: UK

Re: 1989 900 Supersport running on one cylinder

Post by TheDuctor »

Thanks Paso750. There was indeed fuel all over the engine and the floor. The blue wire runs to the battery negative terminal. I guess I'll start the elimination process at the weekend. I did try swapping the HT leads over and the same cylinder still wasn't running, so that's one thing I guess.
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bmw851
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Re: 1989 900 Supersport running on one cylinder

Post by bmw851 »

Um err G, if I'm not mistaken the N terminal on the battery is disconnected, god knows what that blue wire is meant to be attached to, and it would have been pissing fuel under pump pressure if the battery was connected with the split Y piece, so I think the post date has some relevance, if not I'm very scared indeed, and will go poke myself in the eye with a blunt stick, just because I can. :shock:

Himself

I'm going outside with my blunt stick now
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bmw851
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Joined: Tue Mar 13, 2012 9:02 am
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year: 1988
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Re: 1989 900 Supersport running on one cylinder

Post by bmw851 »

That hurt........... :banghead:
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TheDuctor
Posts: 36
Joined: Wed May 01, 2013 7:43 pm
model: 900 SS
year: 1990
Location: UK

Re: 1989 900 Supersport running on one cylinder

Post by TheDuctor »

In no way is this an April Fool! I disconnected the battery terminal because I was trying to get at the coil
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bmw851
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Re: 1989 900 Supersport running on one cylinder

Post by bmw851 »

OK not April fools joke :(

Then in that case the broken Y piece would be the most obvious and foremost problem to start with, fix it 1st before anything else, I may be a bit mechanically challenged myself, but if the bike started fine and was running along alright until you stopped and filled it up and tried restarting it, and I assume there would have been a strong smell of petrol by then? and it cut to one cylinder and died that should be the culprit, fuel starvation pure and simple.

If that doesn't work, move onto the next suggestion, one thing at a time. :D

Cheers

Peter
So long, and thanks for all the fish...............

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