HI all   Just need a bit of advice if poss please   I've got a Ducati 900SS (1991) and I changed my old ngk plugs for some new Iridium ones about a week ago.  One of the old ones was very white but dry (i am told that this could be that it's running weak) and the other plug i took out was very black and oily which i immediately thought might not be how it SHOULD look.  So, yesterday i took out the new iridium plugs just to have a look and one is now looking REALLY oily. I have checked out a plug colour chart thingamyjingamy and it says this about the oily one......   'Too much oil is entering the combustion chamber. This is often caused by piston rings or cylinder walls that are badly worn. Oil may also be pulled into the chamber because of excessive clearance in the valve stem guides. If the PCV valve is plugged or inoperative it can cause a build-up of crankcase pressure which can force oil and oil vapors past the rings and valve guides into the combustion chamber.'   I have been asking around but am receiving conflicting advice along the lines of 'could be piston rings, it's gonna cost you lots of £100s whatever it is'  'it's just running weak on one and rich on the other - so not a huge prob to sort' 'get a compression test done first to see if there could be some real damage' 'get rid of the bike QUICK!'   Can anyone help please?? Thanks so much Raquel x                                                                                                                                                                             

Perhaps i ought to add that very occasionally she seems to only run on one cylinder but soon rights herself and this is often after sitting in traffic.   However, i took her out on Sunday for just a short ride and she only ran on one cylinder the whole time                                                                                                                                                                              

Right, I'm not a Ducati expert, and I'm the other side of the country from you, so don't take anything I say as gospel truth. It could be piston rings/valve guides as you say , but look hard at both the carburetter set-up and the ignition system first as either of these could be the source of your troubles and will cost a lot less to sort. You could try joining this forum if you haven't already: http://www.ducatisti.co.uk/ otherwise it's a case of finding a mechanic in your area you trust. Keep us posted as to how you're getting on.                                                                                                                                                                               

hi dulali first check your oil does it smell of petrol if it does carb over filling  do not run engin untill u have put new oil in   if piston ring have gone you will see blue smoke come out of exhaust when warm                                                                                                                                                                             

A compression test wont set you back very much.might be an idea to have one done & tb500 is right in what he say's. So have a look for that too                                                                                                                                                                              

I've posed this question to a mate of mine who is a bit of a Ducati expert (so he says lol).  I've had to e-mail him so I don't expect a reply in the next 24 hors, but I'll let you know as soon as I hear anything from him   Personally, I haven't a clue.....sorry lol                                                                                                                                                                             

If its piston rings then you will notice the bike using oil quite a bit (old yammy exups were quite thirsty from new!) If the bike puts out blue smoke when warm then its burning oil but this does not automaticaly mean worn rings it could just be valve guides and I'd tend to favour this over rings if the bike is under 40,000 miles ( i once had a cbr600 with 72000 on the clock and was running on the same rings!...never used a drop of oil!)   Smelling the fouled plug is the first thing to do.....petrol is also a degreaser and detergent by nature so it will pick up any dirt etc on its travels so an "oily" looking plug may just be petrol.   If it does whiff of petrol then your carbs float valve is worn or sticking.....get a local independant shop to clean and set up the carbs for you ...a new float valve is only about £5 and to set up and clean carbs wont cost a great deal.......funnily enough if its a sticking float valve then a damn good ride can often sort it.   right at the bottom of your float bowls will be a little screw....hold a small bowl (or aerosol cap) under the little outlet on the float bowl and undo the drain screw..........filter contents through some kitchen paper....you will probably have a load of crap in the carbs that looks like fine silt...if ya do then its carbs off and cleaned time!                                                                                                                                                                             

Raquel,   My mate says you'll have to bring your bike round for him to have a look at it, guess he's just wanting the moolah out of you (poo!)   Sorry I couldn't help any more, but hope you get it sorted.                                                                                                                                                                             

A compression test sounds like a good idea to start because it's free (if you know someone with the gear) and doesn't mean stripping the whole thing apart. Aside from that, it could be anything from incorrectly set up carbs to piston rings gone in one cylinder or a simple case of the desmo valves needing adjustment.

Does it emit blue or black smoke from either pipe? Is the cleaner plug white or a light brown? Were the plugs checked after it had been ticking over for a while, or did you do a plug chop under load?

There are so many questions and possibilities that it's almost impossible to diagnose a fault like this in a text medium.

Btw, I have a compression tester here with a variety of adaptors to suit all plug sizes.

Do one thing at a time...   Compression test 1st. Ignition system 2nd. Carbs 3rd.   Just had to do the same after I did the performance work on my KZ1000 and it may not be as serious or as expensive to sort out as you think.                                                                                                                                                                             

  Hi Ozzy1000 I reckon Dulali got it sorted by now, possibly, cos this topic was started in September last year.                                                                                                                                                                               

Was thinking that meself...if you're still with us Dulali, how did it work out?                                                                                                                                                                             

Must read dates 1st.... must read dates 1st...lol