Ducati 900ss Running rough

**sopachrga** · 2nd February 2016, 20:08

Hi guys

I've picked up an older 1993 Ducati 900ss.
It hasn't been ridden much for the last year or two, and as expected it's running like s**t.

On cold start, it won't idle at all. It has to be ridden for 10 mins or so before it'll idle.
For that first 10 minutes, the bike is VERY low on power and sounds rough. At some point it 'magically' and instantaniously smooths out and gets full power (This comes as a shock when it happens!).
It will also idle from that point.

In saying that, even once it's running at full power, it's a bit rough and surges at low speed. Also back fires pretty impressively on deceleration.

I've checked the plugs, they are new, and gapped properly. They look nice and clean.

Where should I start looking to fix this?
Should I just take it to a shop and get them to do a full carb setup?

**SVboy** · 2nd February 2016, 20:26

I can't really help with your issue but I suggest Duane of Duanes bikes n skis as a very competent Ducati mechanic. Located in hornby.

**sopachrga** · 2nd February 2016, 20:27

Cool, thanks for the recommendation.
Will give him a call if all else fails.

**Voltaire** · 2nd February 2016, 20:28

My mate bought a 600 and it was doing that, turned out to be an ignition module. They have one per cylinder.
Fastbikegear do an ignitech drop in unit, don't waste time or money on Ducati ignition units.
The carbs take a while to warm up too.

**sopachrga** · 2nd February 2016, 20:33

I'll check them out.
Thanks

**Big Dog** · 2nd February 2016, 20:49

Before you pay someone it may be a good idea to drain your fuel and top up with fresh stuff.
This is sounds an awful lot like the carbed bikes that live here when left for longer than 2 months.

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**AllanB** · 2nd February 2016, 20:53

Agree re fuel. It is good for about 6 months before it starts to deteriorate. Had a similar issue years ago with a bike I had had sitting for some months - went through everything with no improvement and as a last resort drained the fuel and float bowls and put fresh stuff in. Fixed.

**sopachrga** · 2nd February 2016, 20:55

I've put about 450kms on it since I got it. So it's had a couple of tanks of petrol go through it now.

Would it still be worth doing? I would have thought the old fuel would have passed though or be diluted enough by now?

**Big Dog** · 2nd February 2016, 21:00

Does your choke move freely?

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**sopachrga** · 2nd February 2016, 21:04

It does seem to move ok. But it doesn't seem to do much when it's on. I can see it moving the sliders on the back of the carb as I operate it though.

I would have expected it to increase the revs when it's on, but it doesn't seem too. It will make it stall if I turn it on while the bike is hot and idling though. So I guess that means it's working ok?

**Big Dog** · 2nd February 2016, 21:24

Originally Posted by sopachrga

It does seem to move ok. But it doesn't seem to do much when it's on. I can see it moving the sliders on the back of the carb as I operate it though.

I would have expected it to increase the revs when it's on, but it doesn't seem too. It will make it stall if I turn it on while the bike is hot and idling though. So I guess that means it's working ok?

I don't know the techy reason but your choke doesn't seem to be doing much choking cold.
Carb cleaner maybe?

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