Dell'Orto SSI rebuild question

[blaat!]

So I'm rebuilding my Dell'Orto SSI29D and it needs a whole bunch of parts. I think it might have even been in a swamp for a time - all the springs were at least partially rusted away, slide was stuck, etc. As a quick aside, I found that soaking in diesel for a few months softened the varnish into a gummy gel, then a quick soak in a gallon of Berryman chem-dip cleaned them up in short order. I have inspected and cataloged all the parts and most of the brass parts still look serviceable. What I really need to know is which items should be replaced during a proper rebuild, even if they look good.

These are the ones I'm on the fence about:

Main Jet
Needle Jet
Needle


To complicate it a bit, the carburetor probably came off a Guzzi and not a Ducati so I'm wondering if all three of these items might not be original and/or optimal for a Ducati 250, and should be replaced...

[joe46ho]

Jim, In order to tell you if these parts are correct we will need the numbers from them. What makes you think it came from a guzzi ? It is possible yes, but if its a SS129D and has the correct 12 degree float bowl, fuel inlet fitting, jets, needle, float, etc... I would think it would be impossible to tell them (guzzi and ducati installed SS1) apart from each other since they have no serial number. As for what I would replace "just for kicks" ? Nothing aside from any worn or damaged parts and the paper washers of course, and most likely the filter screen at the inlet. Parts for these are so expensive I wouldnt buy anything you dont need thats for sure...Now if this carb is from another non-ducati motorcycle (or even a different model ducati single) you will most likely have some incorrectly sized parts. The numbers will give us a better idea of what you have. A quick look at my parts book says you should have the following (assuming it is totally oem original)

A "100" Cut slide (stamped right on top) (This doesnt seem correct but i could be wrong see my note bellow about parts book inaccuracies)
A 14 Gram Float (stamped right on top)
122 Main jet (125/128/130 shown as "on request")
265 Atomizer
#50 Idling Jet
12 Deg. Float chamber
An M14 needle with the clip inserted into the 2nd notch (# is hard to read sometimes but is engraved into needle)
a 29mm "choke tube" of course (the venturi itself) This is what makes it a "ss1 29" instead of a 28 or 30 etc, but these can be changed, they are held in by the "Atomising jet"

I also just realized the book specs out a ss1 29 A for a 1965 mach 1/mark 3 I dont know if that is correct, either for the european models or the usa imports, but I think yours is a 1966 and I think it should have a ss129d. Honestly I have a ss128A here in front of me and the only glaring difference i see is the location where the idle jet, and adj. screw, screw in. I am not sure if the "d"s superceded the "a"s but I have never seen them mentioned after the 1965 model year.

As a side note I finally found an original 1966 Specific parts book and it should be arriving in the mail soon. I have asked around on this site about it but nobody seemed to have one. Once I get it i can tell you what it says, I could also scan pages and upload if necessary.

One other puzzling thing is that the picture shown in the shop manual IS OF a ss129D not an A (even though the parts list says "SS1 29 A"... you can tell because the A has the idle jet screwed in at an angle and it is on the engine side of the carb, as well as the idle screw (items 020 and 048) But on a D the idle jet screws in vertically, and is installed (as is the adj. screw) on the air cleaner/inlet side of the carb, as pictured in the manual...

http://www.motoscrubs.com/Ducati_Manual ... ge_060.jpg

http://www.motoscrubs.com/Ducati_Manual ... ge_061.jpg

ONE LAST NOTE
the slide part number/description says "100" in the mach 1 parts book and the part number is shown as 0421.27.322 but if you look at a widecase parts diagram for a 350 scr that same exact part # says it is a 80 cut slide...Maybe someone else knows for certain which slide cut # a n/c mach 1/mark 3 should have, but the parts book leaves you unsure about that.

Joe

[blaat!]

Thanks Joe, you make a good point about checking all the part specs. I'm not sure what bike it would have been on originally, but the Bowl has no angle and the banjo fitting has only one inlet.

These are the numbers off the parts:

Slide: 80
Main Jet: 120
Needle Jet: 265
Needle: M14
Float: Gr.14

I have seen the 29A in the spare parts catalog, but I understood that it is generally accepted that the 29D was fitted on the Mach 1 and that might have been a typo. Love to know what you find in the parts book as well as what other 'scrubs think.

So, to be original I will need the 122 main jet. The 80 cut slide will require more research.

[joe46ho]

Jim, If your bowl has no angle it isnt original, however since the bowls are very hard to find you could use a inlet from a 450 scrambler or other single model which came with a VHB carb. this will hold the carb vertical instead of at an angle, whether or not this will cause clearance issues i cant say. A SS129D, or SS129DS (D meaning Destra, or "right", S meaning Sinistra or "left") with a 0 degree fuel bowl and the other parts you listed could have come from a moto guzzi (v7 maybe ?) and probably other makes also... If you have an 80 cut slide and its in good shape, I would run it... They are simply too expensive, and every ss1 I have has an 80 cut in it, so apparently they pretty common. The later mk3 and mk3 desmos spec a 60 cut slide but thats a different engine all together, and honestly i think the 80 cut is correct on yours anyway. certainly for the scrambler (and as you see the part # is the same) I would run the 120 main jet at first if i where you, or maybe ream it out to your desired size, even assuming every single part (aside from the carb.) on your engine is stock that doesnt mean that a 122 will be "perfect" it depends on so many factors. I would wait till its running then tune it. You didnt mention your idling jet size, these are pricey as well but can be found easily (guzzino, dellorto u.k., etc...) Dual inlets are reproduced, sold by eurojamb, guzzino, and others. However i suppose you could simply put a brass barbed "t" in your feed lines to the carb. Wouldnt look original of course though. The A carbs definitely exist and as far as i know they did use them on some older models, But i think yours is supposed to have a SS129D.

Attaching a few pics of a SS1 29 DS fitted to my brothers 450 using the oem inlet flange. This one came from a Guzzi I know that for sure.

Joe

[machten]

For what it's worth...Ian Gowanloch had 60 and 80 slides for SS1 29's in April last year. I paid a tad over AU$30 each for a few 60's which I thought was pretty reasonable given my alternatives (old slide had been "improved"). He must have 80's as well because they mistakenly sent me one of those and Jim said they must have been mixed up between the boxes - so I assume he's got more than a few of them.

Kev

[joe46ho]

That's a really good price, I may have to check on that myself... I could use a 60 and an 80
iangowanloch@bigpond.com
Ian's email if you want to check with him, jim

[blaat!]

I'm planning to use the original inlet stub and acquire an angled float bowl. Trying to make the engine completely stock whenever possible. The pilot jet has "55" stamped on it. Dang they are pricey for what they are... must be made from that rare Italian unobtainium. Thanks as usual for all the insight!
-Jim

[joe46ho]

UPDATE...
I received the 1966 parts manual in the mail today, and it answers a lot of questions i have had about my 3 1966 ducatis
and jim as for yours, im posting some pics but if you cant read them, here is the info...
according to the manual the ss129A WAS used on the mach 1 (and 1965 mark 3 till engine number 00350, and the 1964 mark 3 used a ss127A) However, i believe yours is a 66 mach 1 and after engine number 00350, The correct carb is indeed the ss129d, and the parts differ a little bit, your correct main jet is a 118, and there are other optional jets, the 120 you have may be perfect. the slide is definitely a 80 cut, the "idler" or pilot jet is still showing to be a 50 though, and of course the fuel bowl should still be a 12 degree. None of this means i would buy anything other than maybe a fuel bowl for now though, the parts you have may work just fine, you wont know till its running and you tune it...

This manual is very cool, its the original italian 1966 print, and its in good shape, it has a lot of vital info in it that is most definitely lacking in the earlier narrowcase manuals found on this site and others (like pictures of that illusive 1966 only scrambler battery hold down i have asked about on here many times to no avail, along with the 1966 scrambler electrics, headlamp, etc... and pictures/part #'s for the 1966 sebring, and 1966 only monza 250 "square style" bodywork, 1966 only coil spring kickstart setup, etc...etc...) I would like to post a copy of the manual to the site here but this may be a big job (its 579 pages) So im not sure if and when that will happen, for now if anyone wants anything specific out of it let me know...

Joe

[blaat!]

I ordered the NOS float bowl yesterday from Dell'Orto UK along with some springs, etc. Luckily they were out of stock on the #50 pilot jet so I skipped it. Good to know about the slide and main jet specs. Sounds like you were right - the #80 cut slide is the correct one. I agree that sticking with the #120 main jet until I'm tuning it makes sense.

I cant imagine there is a significant difference between the #50 and #55 pilot jets - I really don't feel like paying $35 for it. Seems pricey, but I guess it is supply and demand. They have them in sizes from #30-#75, mostly in increments of 5. So it seems like a #55 pilot jet would allow slightly more fuel at idle than a #50 therefore making the mixture just a bit more rich, but at idle only. The pilot jet is screwed all the way in and fixed (non-adjustable) at "55", right? I wonder if I will be able to compensate for that with the idle air screw? Or will that just make it rev too high at idle?

[Bevel bob]

My 250 in Mach 1 tune uses a 60 slide, a 110 main and a 260 needle jet. Can't say that it carburates perfectly as it appears to run a little weak off pilot and a bit rich on half throttle ,all the oposite you would expect from these settings, it does have a free flowing exhaust which may be a factor.