KymcoForum.com
Scooters - Big Bore => Xciting 500 => Topic started by: KM19 on February 27, 2026, 11:24:22 PM
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Hi Guys,
I have bought an AK550 premium 2023 second hand and have already replaced the CVT / spark plugs / cleaned the throttle body and replaced the fuel filter and wet clutch plates
but when I try to cruise at low speeds (15-30kph) the Bike seems to jerk a lot any ideas what might be causing this? the feeling is kind of like its engine breaking but the engine is misfiring ish very jerky in both deceleration and cruising in low speed but the bike is very responsive and has good performance in high speeds its just low speeds that I have this problem
the bike has the current setup
Speed Evo full cvt 16g rollers
malossi clutch with the "mid" clutch springs
has an open pipe
AFR tuned
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Welcome here!
Not an AK 550 owner but saw several during last years.
My first suspect would be...start to rebuild there!
"the bike has the current setup
Speed Evo full cvt 16g rollers
malossi clutch with the "mid" clutch springs"
Symptoms you describe COULD, I say could be (because this scooter is and reacts completely different from our other rides) caused by following issues:
-throttlebody
= messed up TPS coz of cleaning
= NO proper reset
-jerking and shuddering
= wrong oil
= fuelpump dying
= injectors faulty
= inexpensive belt(s)
= clutch worn (see pic) original plates used?
- ignition jerks
= corrosion on sparkplug connectors (see pic)
Only way to find out is to start at point zero again with search or rebuilt all features to OEM stuff. Proper work on this scooter requires deeper technical understanding.
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On my Kymco the severe jerking at low speeds (as though someone was turning the key off and on!) was a failed throttle position sensor. Required a new throttle body.
Stig