350 Sebring

[libman]

Any advice would be much appreciated on the following:

I am near completing the rebuild of a 1966 Sebring. I have opened up the manifold and fitted a 32mm Amal Concentric. It starts and runs (eventually!) but struggles on tick-over despite adjustments. A more knowledgeable friend has suggested trying a Mikuni and a local firm has quoted me for a VM34.

Does anyone have any experience of using Mikunis and could suggest what jets to try ?

Thanks

[Jordan]

Those seem like large sizes for a Sebring.

This is a saved message, for a late model Ducati single - Spanish I guess.

"A Ducati 350 circa 1973 would have been equipped with a 930 Concentric. As
shipped from the works, the 930/417 had a 220 main, 30 pilot, 3 1/2 slide
.106 needle jet. and a four stroke air tube (928/072)."

Sebring inlet port has diameter 24mm, 1973 model has 29mm.

[libman]

Hi Jordan,

Thanks for the info. I opened up the manifold and fitted the larger carb (it came with a 24mm Dell Orto) to give it a bit more “oomph”. I had delusions of staying up with 350 LC Yams which were all the rage then.

I’ll check the Amal jets and needle settings now.

Thanks

Dave

[Nick]

Pilot circuit probably plugged up. If turning the air screw in and out has little to no effect the pilot circuit is plugged. Go to a music store, get a .010" or so steel guitar string (you only need a couple inches of it, remove air screw and push the guitar string all the way through to the other side to clear the blockage, then blast with compressed air and spray cleaner.

Don't bother trying to clear the circuit with spray cleaner alone, it won't work.

Stripping the carb, soaking in lacquer thinner, then blasting with air may also clear it.

I run a 28mm Mikuni on my Sebring, carb was one of two jetted for a Triumph Bonneville — runs fine with the Triumph jets. After all, a 650 is just two 325s right?

[Nick]

Sudco has jetting specs.

34mm is too big -- 28mm for street is ideal. 32-34 for a full-on racer.

[libman]

Thank you Nick,

As the carb hasn’t been used, I didn’t think to check the state of it, but it has been lying around in a dusty garage. I will check it out.

Cheers

Dave

[ecurbruce]

Hi Dave,
Nick said," Pilot circuit probably plugged up. If turning the air screw in and out has little to no effect the pilot circuit is plugged. Go to a music store, get a .010" or so steel guitar string (you only need a couple inches of it, "
Yes, if you go to a music store where they string guitars in house, after installing the string, they snip off the extra string salvage end, and throw it away. All you need is that salvage end of the high "E" string.

Bruce

[libman]

Thanks Bruce,

I have an old set of strings somewhere in the house, I’ll give it a try.

Cheers

Dave

[el_guru]

Please....... don't just go shoving random guitar strings in your jets.!!!!

Do it properly and invest $5 on a proper set of micro drills and use the correct size.

https://www.ebay.com/itm/20pc-HSS-Micro ... 0#shpCntId