The bike is a 2001 FLHPEI, converted to carb, 98 big bore, 10:1, no headwork, Andrews 37G, RB Racing exhaust, Killer Carb CV40, Dynatek ignition.

The bike runs really well, especially after getting the Killer carb. Starts fine when cold, with the choke. However, after I ride it and try to start, it has a very difficult time. It will occasionally backfire when starting, and when letting off high throttle. I'm thinking it's related to the carb, just not sure.

Carb build specs:
Main jet #210, .080
Pilot jet #52. 018
3 stage adjustable needle, down 4

 

I asked Dale from Killer Carbs if he could help:

New message from: dale1979ta (5,726)

No the jetting is fine. It sounds like it got loaded up (flooded). If you use the choke when the bike is warmed up it will flood. When the bike it warmed up and you try to restart, it should start right away without the choke. If it doesn't start try opening the throttle while cranking until it starts. Make sure you turn off the gas when ever you turn off the motor.
If you continue to have problems let me know.
Dale
Killer Motorcycle Products

 

I was going to suggest make sure you shut the petcock off when you stop the bike. After awhile, it just becomes habit.

If my bike is warm, I usually give one twist of the throttle and fire it up with a partial twist of the throttle while cranking and it starts right up. The twist of the accelerator pump squirts gas in the carb/manifold so it kind of acts like a prime or "tickler" like on the brit bikes.

I have been playing around last summer with starting it in the morning when the engine is cold by giving it 3 or 4 twists of the throttle and no enrichener before hitting the start button. It will start right up but I need to work the throttle to keep it running for the first few seconds. Then I just use the throttle lock to keep the rpm's up till the engine is warm. YD

 

I tried it a couple times and it seems to work; opening the throttle a little while cranking and no choke - started right up.

 

Still difficult to start, especially after getting gas, just a short, quick stop.
I try rolling the throttle when cranking, and every now and then it starts, however, not always. After it seems it's flooding, I crank with no throttle and wait till it kicks, then twist and it starts. Still a a bit irritating.

 

Are you sure carb and jets are clean, float is properly set, fuel inlet needle seats properly shutting off the fuel to the bowl at the proper level and the needle jet is installed correct way up (not main jet but needle jet), and finally the idle mix screw has the spring washer and O ring installed properly?

Sorry, basic questions but yah never know. Some common mistakes is needle jet upside down, an old o ring left up in the idle adjust bore or missing all together. Finally, intake seals? I can understand your frustration, it should fire up easier than it does. YD

 

Got one of these on your intake manifold? (It's a MAP switch, upside down in pic). Check for positive connection, and voltage (5v). Sometimes they fail. You won't see a DTC since you're using aftermarket ignition

 

The petcock should be off when not in use like said it'll become a habit as it should be. with carbs you don't choke after it's warm and unlike EFI you crack the throttle right as it fires. You'll catch hell trying to crank it at idle

 

How do I check this? Disconnect it and check for 5v? I guess I can pick one up and try it.

 

What did you mean by your last statement?