Cylinders 1&2 Not firing

[UselessGoose]

Hey all first post here but I have been creeping your forums for awhile now.  This particular problem has been asked about before but I couldn't find any threads that posted how they solved the issue.

Anyway what I got is a '82 CB750 she sat for 10 years before I came along.  I cleaned out all the Carbs, changed the spark plugs put in new gas and fired her up. I eventually came to realize that Cylinders 1&2 weren't firing.  They are getting spark, timing looks fine, the spark plugs are a little wet and black, there is fuel in the bowls, the spark plug wires seem to be hooked up to the coils in the correct order and the compression is (1) 120 (2) 90 (3) 120 (4) 120.  After seeing that I took off the valve cover and checked the valve clearances, All except 1 of the intake valves on cylinder 1 where less then .004. The cylinder 1 intake valve was .004.  

So obviously that is a problem but since 3,4 are firing I cant figure out why 1,2 aren't. Any guesses?
 
Goose

[TOOLS1]

Since 1 and 4 are on the same coil, and 2 and 3 are on the other coil, we can pretty much eliminate the ignition. I would go back and clean the carbs again. Make sure you can pass a wire (a guitar string works really well) through all the passage ways. They are very small in these carbs, and can get plugged up very easily. Have you tried spraying a little starting fluid into 1 and 2 while cranking? If you do this, and it fires on those cylinders, you will know it is the carbs for sure.
TOOLS

[UselessGoose]

Okay I tried using the quick start and it worked so I am currently ripping the carbs apart to see about the passage was.  I just noticed that the cylinder 2 carb pilot jet  (or whatever jet that is plugged on the other 3 carbs) is  not plugged is that Normal, or an issue.  I can't remember from last time I cleaned the bowls
Goose

[UselessGoose]

Well it appears as though you were right Tools.  Though cylinder 2 still seems a little suspect.  It's exhaust pipe doesn't  seen to be getting as hot ad the other 3.  I am assuming that might just be due to the compression being 30 psi lower then the other 3 though
Goose

[shinyribs]

Sometimes you can get a tiny little piece of debris lodged in a carb circuit. Cleaning the jets is only half of the game, the other half is blowing out the passage for that jet. But sometimes you can get lucky on an issue like this byt starting the bike and holding your hand over the carb that you suspect might have a clogged passage. Maybe even give it a few revs. Holding your hand over the carb opening will force the vacuum to pull exclusively through the carb passages and sometimes can dislodge a stubborn piece of debris lost up inside some internal passage.

Your hand is gonna get soaked with fuel and you'll likely flood that cylinder when you do it, so just let it run for a few moments to clear out any flooding that may occur.

This is not meant to be an alternative to properly cleaning carbs! lol  But sometimes these little tricks can get you going again, at least.

[UselessGoose]

Hey guys thanks for your help.  A combination of all of that seemed to work well.
Cheers
Goose.

On a different note I ended up having to put in a New Rotor and I used a gear puller to pull the bad one out., and some how managed to bed the bolt that holds the rotor in place... i put the new rotor in and it seems to work and be held in place but now I am worried that the bent bolt will through off the balance of the crankshaft or something along those lines causing a lot of engine damage.  Thoughts... I could just be really paranoid!

[TOOLS1]

You bent the bolt? I would replace it, the structural integrity has been compromised, and it could now have a crack.
TOOLS

[UselessGoose]

Yea I don't know I guess all those curls are really adding up ha ha.  Do you know a part No. or what the Thread size on the bolt would be.  I was gonna pop it out today and see what I could find quickly in town here.
Goose

[TOOLS1]

I do not know the thread, but here is the part# 90023-425-000
TOOLS

[UselessGoose]

Thank you very much Tools.  I'll put my bike back in the shop and wait.  Maybe Ill redo the Pistons and Valves while I wait that way I can't ride it! :)
Goose