It is printing slowly and says ''motor throttling''.

Before you even start looking at your bike you need to find the fault code
How to access fault codes and what they mean, once you know the code then it makes life easier here is a link of how to retrieve the codes and what they mean, its good to print this off and keep for future use

http://www.thunder-max.com/techdocs/HarleyDiagCodes.pdf

it may all be in the carby settings
if you do not have it adjusted correctly then it may be running too lean at full throttle and that is causing a problem such as detonation causing the knock
start it and slowly adjust the settings as you increase the throttle settings

take it in to a service center for a proper diagnosis and quote

Start the bike and you can see there is a screw loaded with spring the carburetor just push inside one thread now you can see increase in Idling speed I mean throttle. Now check for a small brass screw which is little inside now just push the screw inside fully. now very slowly unscrew the small screw in certain point you can see there is a increase in throttling stop when you reach maximum throttling.Now unscrew the spring loaded screw slowly till you get the normal Idling.

Sounds like your carb needs the fuel/air mix adjusted..uses all the gas at high speed but has excess at low speeds...find your adjusting screw and at med throttle slowly screw it clockwise until the engine starts to sputter then back it out until it starts to sputter again then continue to do this until you reach ideal mix where it runs the best it can..then go slowly through the throttle up and down..when set..unjust your idle speed screw to your ideal idle speed..if this dies not fix ..carb will bed cleaned or rebuilt. Good luck.. Note always push or pull your throttle handle slowly to position avoids gas load up causing sputter and backfire.

is your car got injectors system or carburetor is it diesel or gasoline ?

Sounds like a bearing gone in the drive shaft or a worn gear

P2103-tac means High Idle Speed

I run a 175 Evinrude set up similar to this one.
If there are no warning lights or warning beeps you will have a restricted fuel filter or fuel line.
The reason you can throttle up slowly is because it takes less fuel flow to get to that point that way.
And at full throttle it takes more fuel flow to maintain speed.
If there are warnings you will need to get it scanned to find out the cause and have it repaired. Warnings can slow down the engine to help prevent engine damage.

i have the same exact problem on 1 of my sons MX5s..i checked all 3 batteries and all that! you left out the controller clicks when the back wheels sapose to be moving ,it's not....so worse case scenerio batt,controller,motor,(650 This time)& throttle....So theres our blue print...lets hope it's just the batteries....!

Take car for trouble code at Autozone or similar store for free. it is probably the idle position sensor.(IPS)