[tooseevee]

The JRC is a copy of a Keihin 30mm D-slide carb.
They take an OKO 30mm and install a mounting flange. The OKO is a copy of a Keihin PWK 30.

            Boy, was I wrong 

[blasphemous]

I have the same problem, I put in a new airfilter and pipes, so I put new jets on the 0 to 1/4 throttle(pilot jet?) and left the main jet stock. Since then I have had this problem. Does it 3 times out of 5, when I transition from pilot to main jet , it skips a beat. By skipping I mean the engine behaves as if it is ready to stall. I am thinking that maybe it is because there is not a smooth transition from pilot to main jet at the transition, throttling the supply of fuel. I am going to go up on the main jet 1 level and see if it helps. Will keep you posted.

[Dhastings1954]

Took the petcock out and there was a screen filter but it was not clogged.
After riding several hours today I would say the carb cleaning helped but did not cure. When it is NOT skipping it runs great. When it does skip I can find a place on the throttle above or below where it runs good. WTF.
Going to put in another new plug, change the plug wire and maybe a new coil and see what happens. Pretty sure the coil is original, so 20 years old.

[Adrian II]

I have the same problem, I put in a new airfilter and pipes, so I put new jets on the 0 to 1/4 throttle(pilot jet?) and left the main jet stock. Since then I have had this problem. Does it 3 times out of 5, when I transition from pilot to main jet , it skips a beat. By skipping I mean the engine behaves as if it is ready to stall. I am thinking that maybe it is because there is not a smooth transition from pilot to main jet at the transition, throttling the supply of fuel. I am going to go up on the main jet 1 level and see if it helps. Will keep you posted.

Transition from the pilot jet is not directly to the main jet, you need to consider the size of the throttle cut-away, the needle size and position and the size of the needle jet itself.

A.

[Dhastings1954]

 Another symptom. My plug is black with carbon buildup. It used to be nice clean Brown. I would have thought this a symptom of too Rich a mixture. Could it also be from poor spark and failing coil??