Hello. I'm new to the forum but a long time rider and mechanic. Been around HD all my life but only owned a couple.
Just picked up an 05 RK fuel injected model. Love it. I love how it handles for as big and heavy as it is. I mostly just love everything about it.
I've not yet pulled a fuel pressure test but have had the tank opened up and cannot see any issues in there like bad fuel hoses.
Bike fires right up with no hesitation. But while its warming up it keeps dropping a cylinder. I screwed a new set of plugs in it and noticed the front had oil fouling. Not a big concern for me.
Yesterday I pulled them to do a compression test and noted the rear was like new. The front had some discoloration. Maybe 100 miles on them.
Compression was 130 front and rear. Happy.
Theres a lot of popping on decel and when very light cruising or very low speed with just a very minute amount of throttle applied there is a cylinder dropping out.
When accelerating or cruising at speed in top gear no issues. Feels good all around. But idle isn't right and that dropping out under light load.
Any help?
It has aftermarket slip ons and according to my Snapon Modus edge the PID list shows a line item that says Next Gen race tune installed....yes. so I assume it's been flashed.

 

First: with access to and knowledge of how to use a tool like that, you are way above me ...
Why not? How many miles on the bike?

Anyway, did you log anything with that fancy tool (that I can not afford) like O2 voltages for each cylinder, long and short term fuel trims, injector power?

I would try logging items above to see if anything is amiss, but just from symptoms described I would start by checking (simple) for an intake leak.

Curious to see what you find.
.

 

OK some models especially rubber mounted models have the injector wires tied to the frame to short & tight and with the motor movement the wire breaks just at the connector to the injector and makes intermittent contact.


Stick a small wooden dowel up under the injector wiring and wiggle while the bike is at idle and see what happens.

 

05 does not.use o2 sensors. Open loop system.
I did a fuel pressure test yesterday and that is solid. Just above 60psi.
I feel it's a bad injector at this point. Pulled plug wires one at a time. Front ran smooth for just being one cylinder. Rear sounded like it was laboring. The wiring looks good. I have lots of experience with that in my field of work.
I will keep the thread updated.

 

45k miles

 

Checked fuel pressure Sunday and it was just above 60 psi

 

Should be more like 65-67lbs.
remove the gas cap and stick your ear onto the filler hole and then turn on the ignition with the kill switch in the run position.
Listen for a noise similar to what pissing on a flat rock would sound like.
These early bikes commonly will wear a hole into the pressure line (original line was too long) inside the tank. Just opening the fuel tank up without running the pump will not show a pin hole.
Other than that, tuning the bike will rear its ugly head if there is a fuel delivery issue.
Bob

 

I've had the tank open and all that looks spot on.
Only issue I do see is the quick disconnect isn't sealing. I unhook the line and it keeps leaking.
So I guess I will be replacing that. I think this bike sat a while.

 

No problems if you looked just be aware it gets broken internally and looks fine for all intents and purposes.
Has fooled lots of people over the years who all claim to work for NASA or some high tech company LOL
If you think it is a bad injector just swap them over and see if you are right, would take about ten minutes to test your theory as no-one can guess what it is over the internet.
Quick disconnect can be rebuilt for the cost of 2 o-rings, one upper and one lower one.
Use Viton o-rings
ID .414" Thickness .072" OD .558" bottom o-ring - BS905
ID .299" Thickness .103" OD .505" top o-ring - BS109
Harley part numbers although they don't sell them really are 11387A for the top o-ring and 11105 for the bottom (just don't ask for o-rings for quick disconnect as they will give you the deer in the headlight stare).

 

Vary the engine speed and note the reading of the pressure
gauge. Fuel pressure should remain steady at 55-62
psi (380-425 kPa).

This is from the HD service manual as I thought your figure was a bit high.