I have an 08 RoadKing. Throttle by wire. 19,000 miles. I ride mostly in north Ga.
My Question:
When coming down a hill and engine braking, as soon as I let off gas to apply brake, I sometimes get a quick burst of speed. It is like I twisted the throttle quickly and released it. I only get a 1 second burst (surge), but it is enough to scare me. Down hill in twisties is not a good time to feel a surge. It seems to happen when I have high RPM'S. It's like compression builds up. Sometimes it will take 1 or 2 seconds for it to happen. It also seems to happen if I release the throttle very abruptly. Another way to explain it is: Get in any gear (except 1st) and gas it to the point of changing gears (high RPM'S) and then let off the gas and coast. After a second or two I get the surge. Sorta like the compression build up I mentioned. Dealer install a race tuner ($525.00) because they said it was a fuel delivery issue. Didn't help. This problem is not kicking any codes, so dealer says it doesn't know what to do. Bad part for me is: it doesn't happpen all the time. It is sporadic at best and very hard to duplicate. The dealer replaced the 6 actuator pins in the throttle. My understanding about actuator pins is that if they are going bad I will lose power, not gain it. Didn't help anyway.My bike has a stage one and V&H slip-ons. New race tuner that has been re-mapped once. It has never been dyno tuned.
Any suggestions??

 

The only thing that I have had similar and would equate your situation to, is that when you decel, and as the rpm's get to just about 2000, the newer EFI engines seem to get a shot of fuel before getting down to idle rpm, and that is where you get that little "burst" from. It is not actually accelerating, but there is a moment of no compression decel, so it feels like it. And I agree that it can catch you off guard in a corner.

I have come across several other posts on this and they may have had a proper technical description of why they do this. Some one will chime in with details.