It's a '72 1200 with an S&S super "B".

The bike used to run beautifull, from one day to the next after I cut the choke, the bike coughs and dies.

it has a 28 intermediate and a 66 main.

The manifold is O-ring type, but have checked for air leaks and nothing... Changed the O-rings and the clamps but to no avail... Changed carbs to a butterfly Keihin, and the same. Changed to a Keihin CV, and still.

Also checked head bolts and re-torqued to specs. Solid lifters adjusted.


This is getting rather frustrating...

 

ignition tune up time?

 

Yep.....sounds like a spark issue.

 

If points...it needs a condenser, at least.
If electronic iggy...and kick start, it needs a battery.
If it fires up with e-start...IDK....Broken Maybe? But, I think Intake leak....

 

you cant trust the gas we get in your country or mine sooo - remove the 2 jets and clean them very good blow them out with air, and look into the ends you should be able to see right through the center when you first remove them - clean and see if they look bigger inside if so that was it

 

New plugs, same. old clean plugs, same. New plug wires, same. Changed coil, same. Changed to electronic ignition, same. Changed pick-up, same... Don't think it's ignition...

 

I've cleaned the carb and blew air out every orifice (of the carb... )
The jets are sparkling clean. I clean them with carb cleaner and finish them off by a good soak in solvent (paint thinner) and run cotton thread just in case... I've even used the jet brushes and still the same.
Fuel here in Venezuela is the pits, so I have a large clear filter to see when it's getting dirty, and/or when there is water in it...
To clear up a bit more. It starts like a beauty and warms up fine with the choke pulled. I drop the choke 1/2 way and runs fine... but when I drop it all the way, the bike puffs, coughs, spits and dies.

 

After all this, throw a 29.5 intermediate in and see what happens.

 

I wouldn't run an inline filter...I would ensure the in tank filter is Clean and proper.
After changing carbs 3 or 4 times...I guess I assume the carbs are jetted at least close for a Shovel...But...
I'm gonna go with Stiggy, and wonder what jets you are using???

 

sounds like a big intake air leak