Dell'Orto SSI rebuild question

[blaat!]

Revisiting this thread as I finally have the bike running and I'm trying to tune the SS1 carb, if that is possible. Strangely it has a nice strong idle

My current issue is that the needle jet split in two at the top of the threads while I was screwing it back in. After I got done swearing at myself, I looked at it with a loupe and there was corrosion in all but a small section of the break so turns out it was already cracked long ago.


Anyone have an extra 265 needle jet (1805 type) laying around they are willing to part with? Guzzino and Eurocarb are sold out. I emailed Road & Race but have yet to hear back. Is there a source in Italy/Europe that I missed?

Thanks as always!
Jim

[Duccout]

Try Andy at The Bevel Side of Life, he is in Germany and speaks English.

Colin

[Bevel bob]

It may be that a 260 will do, or if not a little light reaming out with a drill bit !! I had trouble in finding a properly sized 106 jet for a monoblock so used a 105 and reamed it a tad to 1055 which has cleaned up my plugs nicely.

[blaat!]

Great minds think alike Bob... I had the same thought Unfortunately I can only find sizes larger than 265.

BTW, does anyone know what the number means? I was thinking it would be 2.65mm but when I measured the ID of my broken one it comes in around 3.25mm. Seems like too much to be wear, and unlikely the wear would be round. That was with a set of calipers at the tip though... maybe if I look down inside there is a step and that is 2.65mm ID? I'll look when I get home and try to get hold of a pin gauge set to check it.

Yes I'm having ideas of making one if it comes to it

Thanks Colin. I reached out to Andy. Fingers crossed!

[George]

Might be worth contacting Ducati Paddy https://www.ducatipaddy.com/ paddy@ducatipaddy.com

[Bevel bob]

The carb tune will be very much affected by the cam spec and exhaust system. These motors are much more suited to road use with a smaller carb say 27mm and a smaller inlet valve head. The mach 1 was supplied new sometimes with a remote float ,probably because thats what the factory had in stock, the narrow case mark 3 was overtuned and not an improvement on the Mach1, I have had both.

[blaat!]

Ok. Atomizer could not be found so I had the 265 fabricated ($$$ ) and it seems to be working well.

Now another question.

It is still hard to start at times. Once going, it has pretty good pep at low throttle, but when I get on the gas a little harder it starts to break up as the RPMs get higher. Maybe starving for fuel/leaning out?

I want to confirm that the float bowl isn't the issue before moving on to other things. The carb is a SS129D, but it had a float bowl with no angle when I got it. Maybe from a Guzzi, who knows. I acquired the right 12° bowl and transferred the existing guts into it. The float is the correct 14gr float.

Anyone know which float needle would be correct for this carb on a Mach 1?

The one I'm using has "N" stamped on it which means it is 77mm according to Eurocarb's website. There were at least two shorter ones available (M@74mm & G@70mm) which I think would let more gas into the float chamber assuming the distance from the notch to the stop is different.

Hoping someone might know!

Thanks as always!

[Bevel bob]

Its more usual for bad running to be caused by too rich settings . A float chamber at the wrong angle is going to give very rich mixture as the float will stick and flood the carb. A racy cam and a silencer will often cause blowback which will also cause rich running .

[blaat!]

I replaced the float bowl so it is the correct angled one now, but the float needle only has a 33% chance of being the correct one More likely that it is too long. Just trying to rule things out.

[Jordan]

The float level can be checked to confirm correct needle?