Engine popping

I have an intermitant engine popping going down the road. Sounds like its out of time but we just timed it. Thought maybe it was the valves.

If it is just popping while your cruising, but not while accellerating (like to pass), then you likely need to adjust your mixture/air screws, as they could be set too lean after an exhaust/intake change.

If its all the time, then could be a serious air leak somewhere.

GL.

It does it at low and midrange rpm's. Not so much at high rpm's Really noticable at about 25.

Your low-mid range is too rich. If it was too lean it would be surging. Your needles might be set wrong or the mixture screws might be set too rich or the idle jets may be too big. I have no idea what you changed and what it was changed to.

Sounds like an air leak to me. Or a clogged pilot jet/circuit.

Have you tuned the mixture/air screws?

Outside of carb related issues....

Since you mentioned intermittent....

Points/condenser or Dyna E.I. ignition?
If P&C, when was the last time you

changed

, especially the condensers (capacitors)....

Timing Advancer spring weak/sticking//lubbed?

Have you gone through all the electrical checks/measurements depicted in the manual?

Engine frame ideally grounded?

OMR

Might aid diagnosis to add a little choke while riding to see whether it affects the popping.

Good Fortune!

Patton wrote:

Might aid diagnosis to add a little choke while riding to see whether it affects the popping.

Good Fortune!

Ah yes! I always forget about the magical check lever, the choke.

If it gets better suddenly then you were likely lean. If it bogs right down, then you are too rich. A little bog with the choke on is normal, it shouldnt blubber and sputter though.

GL!

I had the carbs rebuilt. Bead blasted, ultrasonic cleaned, and oversized jets for the header and the carb pods.

No I haven't messed with anything since I got the carbs back.

Its a points ignition. It has new points and condensors. Thought I'd buy a set of wires before I did anything else.

customkz1000 wrote:

I had the carbs rebuilt. Bead blasted, ultrasonic cleaned, and oversized jets for the header and the carb pods.

Without the bike its very difficult to just "jet" a set of carbs correctly. There are lots of different perameters in engine operation and air/fuel volume requirements that affect wether to have slightly leaner or richer jets for the different carb circuits.

Try pulling your air filter out, and see if the problem goes away/improves, then you know Otto was right, I mean "ehem", you are too rich on the mid/low circuit.
If it gets flat/worse, your too lean.

To do a basic tune on the mixture screws, turn all of them 1/4 turn in or out and listen/watch the rpm. If the rpms go up, continue... turn them all more. At some point the rpm will start to drop again. Your trying to find the high spot/max rpm.

GL!