1979 XS750 won't start without starting fluid

[750triples]

Hi all,

As the title says, my bike won't run unless I hit it with a little bit of starting fluid.

Once the bike is warmed up, it starts no problem, no starting fluid required. Don't worry, I've only used starting fluid on it a few times to try and tune it.

Obviously the bike is running too lean, even with choke on startup. I just put on a new Delkevic exhaust and pod filters, so I went 2 sizes up on the pilot jet, and 3 up on the main jet.

I previously had the carbs at 3 up on pilot and 4 up on main, but it still wouldn't start when cold.

 

[Bruno_c]

I suppose you have checked your choke system, so I think it looks like a weak ignition.

 

[Slippery]

I have exactly the same issue with mine.
I found the solution to be after squirting starter fluid into both inlets; open the throttle to max. then start.
Because the strokes are offset now the second compression stroke nullifies the first and the second spark doesn't come in as the first has not sufficent force to make the second stroke work through its compression unless it has plenty of juice - the idle mix is insufficent when the motor is cold.