Intermittent severe miss.

Recently bought my second Caponord and have a history riding a Falco for 10 years. My new 2002 Capo has a severe intermittent miss that comes on suddenly at steady speeds and nearly or actually kills the engine. Any opinions where I should begin looking for this evil demon? It feels like a fuel delivery issue, but is not consistent. The bike is a 1 owner with 50k miles. Overall it has been well maintained but neglected over the past several years due to this issue. I plan to do a complete fuel system cleaning and testing, but may be barking up the wrong tree. There was an EFI code 1 after the first hiccup.

No one has had the same or similar symptoms?

Has anyone got the name of a good parts supplier for this bike. I will be diving into the fuel system in 2 weeks and will needs gaskets, clamps and filters.

I don’t own one but it could be a few things.
Certainly start with either air, spark or fuel.
Could be a lead breaking down perhaps but it is most likely worth removing the fuel pump and checking the fuel filters.
I would hazard a guess they have never been changed.
If the pump is anything like a RSVR it will have a large grey inline plastic filter and a tea bag style looking filter under a cover. That will certainly be clogging up with old rubbish and waxy ethanol in the fuel.
Clean that out with fresh fuel and a replacement in-line filter and that I’m pretty sure could improve things.
If you only notice it under heavier throttles or once properly warmed I’d hazard a guess it’s there.
Again however check the stator outputs and the wiring plugs too and from. If they are very hot when running or burning perhaps the reg/rec or the stator is at fault.
Lastly and I doubt it is you could check the air filter to ensure it isn’t clogged.

Thanks, I have the tank on my bench and the fuel pump assembly out. No sludge or varnish present. The previous owner used non ethanol fuel for the most part as it is readily available here in OR. I want to test the fuel pump and replace the filters. Any pointers on testing the pump would be appreciated.

Hi,
When you do a fuel clean just check the tank isn’t vacuuming? Or take it for spin and when it happens stop open fuel cap if you here a big wish of air you probably found the problem.

Thanks, I'll check the vent tubing while the tank is off.

Been checking pressures and voltages. Seems the pressure build up with the engine off is adequate (?) at 59# but I see a drop in voltage at the pump from about 12 battery volts to 9.2 V. The pump runs up quicker and to higher (70 #) with 12 volts applied directly to the motor. There seems to be a significant drop at the ground wire that goes back to the ECU. Again, when grounded directly to the frame, the drop in voltage at the connector to the pump was much less (11.2V). Is it normal for the wire returning to the ECU to have resistance somewhere. Not sure if I can do anything about the voltage drop except wiring a jumper from the positive lead at the relay to the connector going to the pump unit. I did find an internal fuel leak at the connection between the large filter and the fuel hose leading to the outside of the tank. Fixing this gave me about 10# more pressure again with the engine not running. The bike is going back together in about 2 weeks with new filter, short fuel line from filter to fitting inside the tank, new O ring seal, new return fuel line, and new wiring connectors (some of the insulation at the connector was stripped back). Any other suggestions before assembly?

I have finished cleaning the tank and pre filter, replaced the fuel filter, fixed the connector to the fuel pump, fixed a pressure leak on the fuel line inside the tank, and replaced the battery with a LiPo4 at 13.3 volts. Mid range and full throttle is much better but the idle remained rough and the bike died a few times at stop lights when warm. It was reluctant to start a couple of times and scared me. I disassembled the throttle body and cleaned the fuel injectors in my ultrasound tank then in the process of replacing the left hand one, I lost a small stepped plastic washer from the cross over tube that runs through the throttle body. I can't seem to find any parts blow up showing these parts (2 plastic washers and possibly 2 O rings. Any help would be appreciated.

I found the little plastic ring between the cylinders but still only have one rubber O ring. Can't find a parts blow up showing the throttle body with all its fittings. Anyone had this apart and know if there are O rings on both ends of the crossover tube?