[Ducati] 900SS - Wits End

Sat Oct 27 10:02:19 EDT 2007

Doesn't have to be propane about any volatile spirit will work like brake cleaner  etc etc.
  As others have said, going back some years and I doubt I saved it but someone years ago documented the results of many many changes to 900SS, it almost read like a scientific paper. the result the single biggest effect resulted from use of Malossi intakes. In fact if you wanted to get within shouting distance of 90hp it was a necessity.
  The FCRs will require a bit different starting routine but once you have it it generally will not be a problem. they will waken up the bike quite a bit in my experience. Used to be an outfit in Arkansas or somewhere down that way that sold those Malossis. Buddy likely remembers the guy. 
  But if you only want to get what you have running right. CVs can be made to work fine. It usually does not take much, When I have no idea I usually go up on main, slow jet and shim needle and see how that does. I have found in many bikes jetted EPA lean this almost always is an improvement over stock, sometime the increase in main and slow needs to be two sizes up. I have found in many cases something like this actually works better than new carbs. On my wifes DRZ when I was unhappy with the FCRs and full ti exhaust etc pulled it all off took stock carbs and went up on the main and slow two sizes shimmed needle and it ran and started like a champ, and this bike for whatever reason was always cranky as hell starting, very lean jetting. Also the slow jet was so small it frequently clogged with microscopic something, meaning I could never see anything in it but when I blew it out with solvent and put it back together it always ran and started better. 
  Some folks may be more scientific in their appraoch to these things, my approach has usually been see what others have done and try something and see how it does. never overlook the significance of slow jet. I have learned over the years focusing on main and needle often seems perplexing, meaning nothing you do will sort out problem, but increasing slow jet and bam, problem solved. Seen it several times...cause jetting overlaps, it is not just this or that, as you transition across the circuits those circuits overlap so at WOT it is mainly the main jet but other jets are doing a little as well esp as you roll on the throttle.
  Your problem can be many minor things or jsut one. 
  My approach has always been to take apart and clean thoroughly, blow out everything with electromotive parts cleaner being very careful with gaskets which genrally do not like strong solvents, nothing like having a bowl gasket grow on you. And go up on main and slow a size or two. lots of singles and twins seem to be very forgiving of such course adjustments, meaning you would be surprised, runs ok, but runs better but both may work better than stock. Jets are cheap, local Suzuki dealer usually lets me go through their box of jets if i am looking for a couple, I usually have a hundred or so assorted jets from years of messing with this stuff and many Dynojet kits or Factory kits. So it makes it easy to try things.
  i am not saying you have an airleak but it cant hurt to check, it likely is jetting. When jetting is off all sorts of fugged up things happen, from poor starting, does not want to idle, runs on, stumbles...usually not because jets are too big unless you did that yourself. Trash in a jet can do it as well.
  If main is not right often you can tune out some of that with the air screw, pilot air screw etc. But if making course adjustments and little happens that is indication that you neeed to change main. this is partly why a couple main size differences will work, even there is overlap using air screw.  
  Also seems to me much writen in past about emulsion tubes on some of these bikes wearing out from the needle working in them over time, Change emulsion tube and problem goes away. I am no expert on emulsion tubes but clearly they are important, important enough that in some cases where a stock carb does not have one, Dynojet will actually inclde themn in their kit. Seems to me years ago in the 600F2 kit Dynojet included emulsion tubes that sort of shroud the needle in throat. I guess they sort of create like a mini venturi around the needle main interface and help atomize fuel better as it comes out of the main.
  if your carbs have emulsion tubes might want to look at that, what little I remember is that they wear out from the rattling around of needle and the reult is less atomizing which i would think would result in leaner conditions. But dont quote me on that. I have never changed out emulsion tubes on 900SS. Just something to look for if it applies. Rich

Alec Moss <amoss at coastside.net> wrote:
  I'll check with the propane routine. I seem to remember another way of
checking that sounded safer, although I've done this before with my old
(long gone) Triumphs. Do you remember what that was?

Alec

On 10/26/07 2:18 PM, "Rich Roberts" wrote:

> Could be an air leak. Rich
> 
> Alec Moss wrote: Thanks all. The bike has about 10,000
> miles and, in neutral, when I roll on
> the throttle a bit from idle, it rolls on smoothly but won't hold the
> slightly higher rpm. It wants to race a bit. Maybe it's time. :-}
> 
> 
> Alec
> 
> 
> On 10/26/07 9:13 AM, "Bruce Bellm"
> wrote:
> 
>> FWIW, I had them on my SS for 3 yrs. before I sold it. And, living in New
>> England (albeit northeastern CT) it never failed to start using the drill
>> you mentioned.
>> 
>> 
>> 
>>> Alec,
>>> Having ridden both on a daily basis, from this statement I would stick
>>> with the stock Mikuni carbs. The Keihins are a kick in the pants, but can
>>> be a
>>> little finicky upon start up (my ritual is 2-3 snaps of the throttle
>>> before
>>> start up) and they have no choke, so depending on your climate and riding
>>> routine the stock carbs are sounding like the more practical choice.
>>> Now to contradict that, if I only had one carb bike to ride, I would want
>>> it
>>> to have Keihins.
>>> 
>>> Rob
>> 
>> 
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