Number 2 cylinder not firing

Compression tested, checked valve clearances, cleaned carbs countless times, new coils, leads and plugs. Fires on number 2 intermittently but when it gets hot on a run, all 4 fire . It's like if I thrash it all 4 will fire. Number 2 seems hesitant then kicks in. Any suggestion guys?

I do not consider myself an expert by any means, But if it has fuel, compression and spark it is going to fire. I would guess ignition. Unless the bike is fuel injected.. Then I would suspect that.

Im curious to hear what everyone else thinks

If everything you say is true, the carbs are clean and flowing properly, coils are new spark plugs are new, new plug wires .... etc. etc. my first guess would be that you have a short somewhere in the primary side of the ignition coil or the secondary side if a four cylinder and sometimes those shorts are right where the coils mounted to the frame..

Pilot jet clogged. Use a guitar string or wire brush strand to make sure it's clear.
Steve

Assuming the carbs are clean I'm guessing you have a problem with your petcock. The vacuum operated petcock has a vacuum line that runs from the petcock to the #2 carb. When the diaphragm inside the petcock gets wonky (and eventually they all do) it permits fuel to be sucked down through that vacuum line into the #2 carb throat and into cylinder #2. Then the #2 cylinder runs like crap. No fuel should ever be drawn through that vacuum line.

To test - You can remove the petcock vacuum line from the #2 carb and cap off the carb's vacuum nipple and the petcock vacuum line; this removes the vacuum line from the equation. Then install a new spark plug in #2 cylinder, turn the petcock to PRIME, and take a ride. If the problem goes away the petcock needs to be rebuilt or replaced. Ed

So confusing. I'm thinking it might be number 2 carb as there is a good spark to number 2. If I pull the plug from number 2 after it's been idling it looks wet and yet it doesn't seem to be firing. Number 2 exhaust is cold compared to the others. As I said once it gets hot number 2 hunts and wants to kick in. On a run if I crack the throttle number 2 works fine but if I open it gradually 2 wont fire. I've removed the vacuum tube, covered the carb hole and run the petcock on prime, no improvement.

Had the pilot screw out fired cleaner and compressed air through the whole carb

+1 with what Ed said- I had that same issue last year. I tried a petcock rebuild kit, but that didn't last long until it went. This year, I tossed a replacement Suzuki petcock in from Z1 Enterprises, and I don't have the wet fouling issue anymore. Plus the whole petcock is the same price as the rebuild kit... Swaps right into place. You have to re-run the fuel line around the frame between the gas tank and seat due to the angle of the outlet nipple and spin the vacuum line 90 degrees, but other than that, it's more than worth the $40 to do. It's a way smaller petcock too which is nice.

One other issue that comes to mind is your float levels. Not sure if you've checked float levels, but this could be it too. I have this issue (lightly) on one cylinder at the moment that I need to fix.

www.z1enterprises.com/product/KL18-4359

Tested it again last night and all 4 are 125PSI cold, good spark and no breaks in the wires. It must be number 2 carb, but I've cleaned the fucking thing countless times. Gas seems to get to the bowl but not much is getting into the chamber I'm assuming. As I said before once it gets hot it goes fine, totally stumped

Have you checked the carb rubbers?

Yes buddy, think I've been through everything.

With fresh dry spark plugs, have you tried filling all the bowls, pinch off the fuel lines, to be sure the #2 is not sucking raw gas through it's vacuum port? That would be the engine running on stored fuel in the bowls.