Runs strange

[Cavman11]

My 1973 750k runs strange. It starts right up. I takeoff and soon it acts like it is not getting gas. Then it will run fine for a bit then it will not rev for the amount of gas I am giving it. Then it will run fine again. If it had a fuel pump I would think that was the problem. I am not sure if it is a fuel problem or an ignition. Any thoughts would be appreciated. Thanks.

 

[Loose Chain]

What's the history on the bike? Did you just buy it or has it been sitting for a long time, or it was running good and then suddenly started acting up?

 

[brettp]

Sounds like a fuel filter with stuff getting sucked against the filter media and eventually clogging it. Can also happen with crap in the tank clogging the petcock strainer.
Do you have the original fuel pump assembly on the top of the carbs? An inline filter?

 

[Cavman11]

I bought it new in 73. It has not been sitting for a long time. I know several years ago water got in the tank and it was rusted. I did the reline of the tank and I have not had any trouble until now maybe I need to take the tank off and put some marbles in and shake to see if I have any of the lining coming off. There is no fuel pump on this model it is gravity fed. There is a screen in the petcock but is does not seem to be clogged.

 

[brettp]

Sounds like you're gonna have to look. Could also drain the carb bowls to see if something is clogging the jets then settling back down when it dies.

 

[thejet95]

I had a similar problem it would idle fine but bog when giving it throttle, turned out to be my carbs. Had them cleaned and no more problems, power is back.