Runs on back cylinder but front cylinder pops a little when idlin

CHECK COMPRESSION ON ALL CYLINDERS

Dave:
Your #1 cylinder ( the front cylinder) is not firing. It could be that the spark plug is fouled or improperly gapped, or the carburetor is not delivering gas to the cylinder. pull both spark plugs Clean the plugs and gap them. The gap should be about 0.035 In. (thirty five thousandths). Reconnect the wires to the spark plugs. Lay the spark plugs against the outside of the cylinders with the metal part of the spark plug body touching the cylinder (creating the ground part of the circuit). push the starter and look for spark at both spark plugs. If you have spark at both plugs, put them back in and start the bike and check the exhaust pipes to see if they are both hot. If one is still cold, the carburetor for that cylinder is not delivering gas. Could be a kinked or clogged fuel line, disconnect the fuel line from that carburetor and see if gasoline flows out. If gas flows out, the carburetor needs to be tuned or removed and cleaned.

change candle, and regulate the carburetor. the excessive gasoline in coming damage the candles.

Although the problem could indicate a (potentially) expensive electrical fault. It is worth trying the simple (and cheap) fixes first:
Have you tried swaping the Spark plugs (front to rear) If the fault moves with the plug, then A new set will get you sorted.
(Spark plugs may appear OK off the bike, but can break down when under compression)
Can't guarantee that this will work, but well worth a try.

Clean the injectors and check spark plugs.

It seems there is too much of fuel going into the non firing cylinder thus the blackish spark plug, recheck the float level to that carburater and also check the valve clearance.

I had the same thing on my 97 marauder vz800 on the rear cylender it was a stuck ring put ring free in gas fixed problem

I would be checking for air leaks, this will give you a lean mixture. In particular look for the seals for the balance tubes and each carb.

you can loosen the tank at the back by undoing the two bolts that double as seat brackets, once youve done that you can lift it up enough to gain access but it will slip off backwards if you undo the gas tap and release the breather pipe under the tank aswell, the tank is held in place by two rubber bungs at the front that slip into two locating grooves on the tank,, slip off backwards and slips back on forwards,,you wil need long reach sparkplug sockets,, and when putting them back in finger tight them first to make sure youve got em in right