Need HELP!!!

[cb750kfan]

I recently bought an 81 CB750K. It starts right up, and runs fine, but then dies after a short ride. I haven't really done much on bikes, so this is all new to me. If anyone has some ideas as to what is wrong with my bike, it would be great if you could share them.

Thanks, Derrick.

[blackhawkrider]

define short, it dies once fully warmed up? Most likely its fuel related somehow. I would also check for vacuum leaks around the intake boots. Check your fuel filter. Also does your fuel line connect directly to carbs or does it connect into a valve on top of the carbs? Hope I can help

[cb750kfan]

Yes. I dies when fully warmed up. I put a new filter on, new fuel lines, new Intake boots(no leaks), had the carbs pressure cleaned, and ran some seafoam through it. The line connects to a valve on top of the carbs. I have also heard that it might be the coils. What do you think?

Thanks, Derrick.

[blackhawkrider]

the vaccuum hose that connects from the carbs to the valve (autopetcock) may be on the wrong nipple on the valve. There are two 1/8 barbs, the one that points out towards you is a breather the one that points in towards the middle of the bike is the one the hose should be connected to. Otherwise sounds like you have tried just about everything I know of.

[cb750kfan]

I will check to see if it is on the right one. I have also been told that the cdi boxes could be bad. Does that sound like a possibility?

Thanks for your help, Derrick.

[blackhawkrider]

 dont know as much about the ignition system as I do about fuel. Most of the time with bikes from this era is they are old obviously and their fuel sytems are the most sensitive to non use and age so since I enjoy fixing them I have had more time in carbs than anywhere else. Seems most of them have the same problems and I have not had cdi issues yet.