No Fire 1 Cylinder - Maxim-X 750

Hi Gents... Story time!

At the end of last season one cylinder started acting up. ...Wouldn't fire, or would occasionally quit.
And smelled "gassy" when running.

This year I took out of storage and started it up. ...Same thing. ...duh!
Checked the oil and it was full of gas.
Took the carbs out... there was fuel in both the in and out boots, and the air filter was wet.
All the o-rings were stiff so they were all replaced ... as well as one needle.
Mechanic indicated that the floats and everything looked fine.
Reinstalled....intake boots are a PITA!

Drained oil, filled oil with clean, started, drained and added a second batch of clean oil.
Started right up.
Although when I first opened the prime, to fill the float bowls, I got a small drain of fuel through the breather tube(From the side of the cold cylinder). ...Not happening now.
1 cyl hung for a bit and then caught.

Next day
Bike starts, but the same cylinder doesn't fire... and doesn't seem to want to catch. (It's a nice warm day!)
Checked the supply boots from the air filter box. ...Dry. ... So that's improvement.

So what could be going on?
Still carbs? or am I into valves? or something else?

As always - Thanks for your love of these incredible vintage bikes!

 

you could have a bad spark plug cap,spark plug, or the wire needs to be trimed because the end is corroded.
sync may not be correct, mixture screw may be out of adjustment,

did you wet set the carbs
Setting the fuel levels
fuel level may be low and your running lean, plugs black and wet or black and dry?

with the first fill of carbs floats can be stuck or neeedle binds and bowls require rapping to ensure they lift and close the needle because they are hanging low.

ohm out the caps,trim the wire.
if wires are long enough move wire 1 to cylinder 4 and wire 4 to cylinder 1 see if the problem moves with the swap.
if it does not move with the swap, swap plug 1 and 4. to see if it is the plugs.
if plug is fouled change it.

next think about the pilot jet circuit/ mixture screw
start by checking fuel levels if ok adjust mixture screw a color tune would be helpfull.
did you do a bench sync then try a running sync?
i had 2 dead cylinders rebenched synced and 1 came back to life.

 

you do need to check valves to eliminate them as problem. what do you have for mileage?
also should be done before running sync

the more things you know that are correct the easier it is to narrow down/find the problem

 

OK re first fill. Good. That's what I hoped the issue was.

Swapped in a fresh spark plug and the cylinder came to life... Awesome.

In doing so I pulled on the wire for another cylinder where it plugs into the rectifier(?)... tried re-seating it...
and now that cylinder is dead!
...and on it goes.
So I guess I test connectivity there now!

 

a spark plug wire?

 

Sorry... seniors moment!
On my old 1970's Duster I would have called it the distributor cap...

On the X ... I guess I'm talking about the ignition coil.
Where the plug caps terminate...
The one attached to the now failing cylinder was loose, so I pulled it out (was that lot's of nice clean lithuim grease?)
... but putting it back in didn't bring the outside right cyl to life.