350 Sebring

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libman
Posts: 4
Joined: Fri Feb 16, 2018 10:52 pm

350 Sebring

Postby libman » Mon Feb 19, 2018 10:08 am

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
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: 350 Sebring

Postby Jordan » Mon Feb 19, 2018 9:06 pm

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
Posts: 4
Joined: Fri Feb 16, 2018 10:52 pm

Re: 350 Sebring

Postby libman » Mon Feb 19, 2018 10:07 pm

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
Posts: 243
Joined: Sat Jun 01, 2013 4:57 pm
Location: Paradise

Re: 350 Sebring

Postby Nick » Tue Feb 20, 2018 6:53 am

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?
Put a Mikuni on it!

Nick
Posts: 243
Joined: Sat Jun 01, 2013 4:57 pm
Location: Paradise

Re: 350 Sebring

Postby Nick » Tue Feb 20, 2018 6:57 am

Sudco has jetting specs.

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

libman
Posts: 4
Joined: Fri Feb 16, 2018 10:52 pm

Re: 350 Sebring

Postby libman » Tue Feb 20, 2018 4:14 pm

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
Posts: 299
Joined: Fri Apr 01, 2011 12:43 am
Location: Lakeland fl

Re: 350 Sebring

Postby ecurbruce » Wed Feb 21, 2018 1:57 pm

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
Posts: 4
Joined: Fri Feb 16, 2018 10:52 pm

Re: 350 Sebring

Postby libman » Thu Feb 22, 2018 6:05 am

Thanks Bruce,

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

Cheers

Dave

el_guru
Posts: 31
Joined: Thu Jun 23, 2011 12:10 am

Re: 350 Sebring

Postby el_guru » Thu Feb 22, 2018 1:48 pm

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

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


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