Topic: Rough RMPs over 4k...Carb issue?

[kurtanton]

Hi,

So, I have had the 73 cb350F out on the road the last couple of days, but I am getting "garbled rpms" if I try and give it gas swiftly above 4000rpms, anything above that is not nearly as smooth as below that level. I kinda chug up hills that are in a 45mph zone, downhill obviously I can make some gains. It seems to be hit or miss off the road in neutral in the garage, sometimes I have a nice smooth powerful run all they way up to 10k, othertimes, garbled right at 4+. The engine will choke through them, and go up higher, but nothing that will get me anywhere on the actual road. I have sprayed some carb cleaner in there, look out the airfilter, and that seemed to make it work better for the time being. But, sure enough the next day, back to crappy rpms. I am thinking it is a carb issue? Crap in the carbs? (How often am I supposed to do that, says the blonde). A float issue? I think I will take the bowls of and clean them out tomorrow. What do you experts think I should start at?

Thanks again,
-Kurt

[cub]

Or old crap from the tank?

[Bob Wessner]

"I think I will take the bowls of and clean them out tomorrow. What do you experts think I should start at?"

When you go to drain the bowls, try cutting a small piece of paper coffee filter and drain them through that into a small tin, like a tuna can (it fits under the carbs better). See if there is any small particles, then examine the bowls. I agree, could be contaminated fuel system; tank may need cleaning, carbs may need cleaning, then install in-line filters.

[Bob Wessner]

Also, any chance this is an intermitant ignition problem? What about the advance mech? On my 750 it max's out at 3K, what is the max on the 350? Could it be a sticking advance mech??