My 07SG with a 113/ Thundermax/ S&S cams, heads and many other modifications is running somewhat erratic under heavy throttle, spitting or miss issue, I did a dianogistic code check and found nothing.

I am not sure if is fuel related or spark?

Any advice from the experts where to start?

Thanks!

 

For got to mention that the plugs have been swapped out for a new set.

 

I'd check to be sure the cam timing is correct. May be off a tooth or two..

 

Was it running well before? Is this a new issue and, if so, what changed?

 

Have fuel pressure checked.

 

Good point. May be clogged fuel filter.

 

Check to make sure the spark plug wires are installed correctly if you just changed them.

 

The bike ran excellent until the last tank of fuel that took forever to pump, I assume that it was the bottom of the Sunoco tanks and it was cold and just wanted to get home! I will first explore the fuel filter. Thanks.

 

oh crap you just diagnosed your problem right there

Drain that crap out of the tank clean your tank out replace your filter and get some good gas you should be good to go after that

 

Just read over the service manual and watched a YouTube on fuel filter replacement, another interesting adventure.