Topic: '75 CB 400 Four, could use some help please. Carb issue and 2 cylinders cold.

[Jay Roller]

Hello all, I've got a '75 CB400 Four that I'm working on making it road worthy. The bike has been sitting in my dads garage for close to 25 years, 15,800 miles. It's pretty clean but definitely not perfect. Photos when I reach 5 posts.   

I bought a battery, drained the rotten fuel, added new fuel and it pretty much fired right up. That said, I have issues.

First issue noticed is the fuel overflow hose from the #1 cylinder carb is leaking like crazy. I'm guessing the float is stuck?
Also, for the short time I had it running only the #3 and #4 exhaust pipes got hot. So, #1 and #2 are obviously not firing. Maybe a coil? Or do could that also be a carb issue?

Any tips on where to start would be appreciated!

Thank you!

[harisuluv]

Coil would be 1&4 or 2&3.  Sounds like you have clogged jets.

[krusty]

I had that 1-2 or 3-4 not firing on my CB750F. Turned out to be old plug caps. This was after cleaning the carbs.