new to me 1978 KZ 1000

I think the Plug wire is ok. I pulled the plug and laid it on the engine. Good spark.
i also swapped plug wires from 2 to 3 and 3 to 2.  Number 2 is still dead.

If the plug is dry your problem is fuel.  If it's wet then it's something else.  If it's fuel it will be in the choke circuit or the pilot circuit.  If you have fuel screws look inside the hole to see if a PO broke off the tip of a fuel screw.  If you followed the correct procedure to check compression and only got 100 lbs I would consider that to be a poor result, but still enough to have the cylinder fire.

Have you checked all vacum caps are in place, a significant air leak will give the same symptom as no fuel (carbs rely on the depression in the manifold to suck fuel from the jets and an air leak will prevent that depression from occurring) if you remove the pod on the bad cylinder and spray carb cleaner into the intake with the engine running does that cylinder "cut in"

I once neglected to reconnect the vacuum line to the petcock. Hard to start and ran like poop. Seems that the Rex prefers to have all four firing. Who knew?

Hey Guys thanks for getting back.
I did check the timing after I installed the Dynatek Ignition. It is spot on.
I did pull the plug and it was dry. I looked it up again, and ya 100 lbs is pretty crappy! Not sure where I thought that was good.
I’ll have to borrow a compression tester. All 4 holes were right around 100 lbs. So it may be a POS!
I forgot to mention in the first post, that I replaced the carb holders and all the vacuum caps.
The petcock was replaced with a regular petcock, non vacuum type, and I capped those as well.
I’ll try some carb cleaner, to see if it will fire.
I’m quite sure it’s a fuel problem, I guess I was really hoping that I didn’t have to pull the carbs again.
The bike starts and runs really nice, just only on 3 cylinders. 

When you capped the petcock vacuum hose did you mistakenly cap the bowl vents?

hardrockminer wrote:

When you capped the petcock vacuum hose did you mistakenly cap the bowl vents?

Umm. I will definitely look into that! Thanks  
Without looking. I believe there is 3 short pipes that I put new caps on. One of the carbs didn't have one. I want to say it is #1 or #4

 

Hey Hardrock
Looks like I did cap the vents. I just found a pic that Patton put on here, 12+ years ago. 
 I haven't tried it yet.
I have vent tubes on Cyl.2,3 and 4. # 1 is blanked off. . But how is it that cyl. 3+ 4 are firing with the vents capped? Or # 1, because 1to2 and 3to 4 have the cross tube !
I will uncap them all tomorrow and see what we get!
I should probably have something on those tubes to keep the dirt and rain out!?

I went back and read the thread from 2012. I think all my questions were/ are answered in the thread.
I will give it a shot tomorrow. Fingers crossed!  

Well it appears I've hit another road block.
I pulled the caps off the carb vents between 1 and 2, 3 and 4. I left the cap on #3 as its the vacuum for the old petcock.
But still no fire. I pulled the plug, It appears to be wet and smells like gas.
Not sure where to go from here? 
How is it that cyl 1, 3, and 4 are firing/ running when the vents were capped? I shouldn't have an air leak. I replaced the carb holders.
I have the pilot screws set at 2 turns out. Could this be too rich?
Thoughts!?
Thanks!

As to vents and vacuum ports on the vm 26 or 28 they work like this.

Keep in mind that some sets so not have the accel pump and some have 2 fuel inlets instead of one. Some do not have the vacuum  port on #3

Do the carb mounts have fittings for syncing ? are they capped ?