Topic: Ran great, then limped home?

[Duuuude]

I spent the winter getting my 1973 cb750 dialed in.
Rebuild carbs, carb sync, cam chain, valve clearance, oil, basically a tune up.
It was running REALLY well after I had been riding it for a little, lots more pep than it had before.
It sat for about 2-3 weeks we got another spell of snow. Took it out yesterday, started right up. About 15 miles after it started bogging HARD. Almost had to push it up the hill to my house.

I replaced plugs, checked for spark. Good.
I pulled off the float bowls, no fuel. Put it on reserve. No fuel in any carb.
I pulled off the sediment bowl on the fuel valve that was replaced last year. No fuel coming out in ON, only in RESERVE.


I woulda thought it was my fuel valve, but seeing as even with RESERVE on its not pulling gas into the bowls theres gotta be a blockage somewhere in the fuel lines? There brand new fuel lines.

Am I on the right path here?

I only run 90 octane, NON ETHANOL. With a few oz. of seafoam

[strynboen]

vaccum in the tank..

[Johnie]

Yah that is a good start. On the inside of your gas cap there is a tent like small opening. I usually blow through it. If you can't it is blocked causing the issue. Or...you can run it and when it does it again open the gas cap and listen for a swoosh. Then start it up and it should run good until the vacuum is created again.