No acceleration?

Ok, so I rode my 1975 KZ400 yesterday and the day before and it was fine. But when I rode it today, it not run so good. I couldn't get it to accelerate and I barely made it back home. Whenever I pull the throttle, it doesn't sound good and it doesn't accelerate. Any ideas?

Thanks!!!

In present state, will engine crank and run enough to enable spraying water on exhaust header pipes to determine whether both cylinders are combusting? Spray will immediately sizzle and vaporize upon contacting the exhaust header pipe from a combusting cylinder. If the cylinder isn't combusting -- for whatever reason -- the water spray will just run off the pipe.

Would remove the spark plugs and "read" them. How do they appear -- sooty, tan, whatever?

Using new correct plugs, attach plug cap and hold plug against engine while spinning engine over with ignition turned on. Look for a good fat spark.

While plugs are removed -- perform a compression test, remembering to hold throttle in wide open position during testing.

Your objectives are:
Acceptable compression psi;
Good spark;
Properly timed spark;
Ample clean fresh fuel supply to carbs;
Proper fuel mixture from carbs into combustion chamber.

Note that carbs are the LAST item to be addressed.

Good Luck!

damn patton, you beat me to the punch,, but good advice