Topic: Loss of power and stalling after riding for 20 minutes?

[deanoevans]

I'm somewhat of a noob here. Forgive my ignorance.

I have a '73 CB350F.  It runs great for about 20 minutes. Then it begins to stall when idling, and I loose power when accelerating. It it us feels different. It gets worse the longer the ride. Then when I let it sit for 30 minutes it runs good again.

I just installed a new clean gas tank. Fuel appears to be flowing nicely from the petcock.

Any suggestions would be greatly appreciated.

[Johnie]

Once this happens again open the gas cap.  If it works good then your gas cap vent may be plugged.  If that is plugged it will create a vacuum in the tank and not let gas flow good.  At least you can eliminate that item if it still does not work.  Once you know we can move on from there.

[Johnny5]

Are your floats set correctly?

Also, what shape are your coils in? Good spark?

[heyjones]

I had this same issue on my 750, turns out it was a loose connection to the stator. So sometimes I could ride for hours no problem, and others I'd get 5 miles down the road and stall out. Then if I let it sit for a while, the battery would "recharge" itself and I could get going again. But if it stalls and you still have power, then nevermind.

[Hush]

Could be coils going bad, they sometimes fail as they heat up then once cool again fire up OK so testing has to be done when bike is hot.
Otherwise could be a charging issue........get back to me if it looks like that......Hush.

[gilesclement]

I've just gotten over similar symptoms, on mine it was the pulse generators failing once hot. Not sure if yours has those or a points setup but if you do have a electronic ignition you can check the resistance on them. Could also be coils.

[Philly550K1]

might also be rich. does it need choke to start? does adding choke during the first few minutes create the same symptoms?

[Duke McDukiedook]

Is your bike stock? (original airbox, jets, pipes, points, coils?).