Topic: 1+2 run hot while 3+4 run cold...

[deanofall]

Bike(80CB750k) will not idle but ran in driveway for about 10 minutes before cutting off.
Pulled plugs - 1+2 = carbon fouled 3+4 looked oil fouled
Touched pipes and 1+2 ran very hot while 3+4 weren't nearly that hot(while running the exhaust for 1+2 was much hotter)

Recently took apart and clean carb three - didn't notice any problems.

In my manual it mentions a Honda valve lifter tool needed to do a tune up - is this absolutely necessary tool? Could all of this be due to valves clearance? Any ideas on what to look for next?

[Dumbgumby]

Same happend to my bike and found that the cold cylinders had no gas in the bowls by unscrewing the drain plugs at the bottom. Not sure if this is the case for you but I guess its the easiest thing to check for.

[csendker]

The first thing that comes to mind is that a 2-port petcock typically feeds carbs 1+2 with one line and carbs 3+4 with the other.  You have fuel flowing out of both fuel lines? 

[deanofall]

I didn't think that I had two. I have a hose that comes off of the rail which I thought was a breather hose. Would the petcock have two spouts?

[deanofall]

Same happend to my bike and found that the cold cylinders had no gas in the bowls by unscrewing the drain plugs at the bottom. Not sure if this is the case for you but I guess its the easiest thing to check for.

I unscrewed all four and fuel poured out of each.

[TwoTired]

The primary issue is that you have one too many cams in your engine.  Half the cylinders are getting confused, what with two different managers of valve operation.

[robbiec]

The primary issue is that you have one too many cams in your engine.  Half the cylinders are getting confused, what with two different managers of valve operation.

I have to agree with TwoTired...it's like that scene from Cool Hand Luke..."Take that dirt out...put that dirt back in.." I have heard in some rare cases that engines can explode due purely to valvetrain confusion.

[deanofall]

Perhaps i should jam fifty eggs each into the cylinders?

[comcrx]

"man says he gon' eat fitty eggs, he gon' eat fitty eggs!"

mine was doing the same thing and I checked the fuel line that goes to 3&4 for clogs, replaced the spark plugs and it was fixed.

all of my carb bowls were getting fuel, BUT, 3&4 were'nt getting as much. when 1&2 bowls would be full, 3&4 would be like 1/4 full

[Dunstall_74]

I just had the same problem w/ my '74 750k except it was 2&3 that were not firing.  I found that the points gap on the points for the 2/3 cylinders was way off.  I don't know if an '80 bike even runs with the old points system though?  Good Luck.