Ignition timing? Engine suddenly lost power after accelerating from a standstill.?

Question

I was accelerating from the traffic lights, and as I was speeding up, the engine seemed to suddenly loose power. No matter how much throttle I applied, the engine did not want to go, it sounded very dull and I stuggled to maintain my speed. Now, i need to rev the engine very high in low gears in order to get it going, and even then, it is a struggle to climb up hills, and maintain even low speeds (60km/h). I need to gain alot of momentum in order to reach higher speeds (80km/h). The bike seems to rev normally when I apply the throttle at a standstill, but as soon as I start moving and changing gears, it becomes problematic to get the engine going, and it struggles to maintain power. The engine now generally has a dull sound, and there is a dull popping sound from the exhausts.

Could this be an ignition timing problem? Or another re-adjustment that needs to be made? Or did I break something....The bike has done about 5700kms. It is a 2006 Kawasaki GPX 250R (or "ninja" 250R in the US)

Answer 1

It`s a bit hard to say without hearing the bike run but if the dull popping sound you describe is coming from both exhausts it suggests the problem wouldn`t be be in the top end of the motor ie. valves pistons, head etc. because it`s rare for both cylinders to go out together. So the problem should be ignition timing or the fuel system. Could it be bad fuel?

If the popping sound is coming from one exhaust it might be something as simple as a bad spark plug, or lead - hopefully.

If you can get hold of a compression gauge & do a compression test on both cylinders you`ll have an indication of the condition of the top end of the motor.

Answer 2

Have you checked the timing to see if that's what has happened? The popping sound you described could come from the bike's timing. It could jump time if the cam chain wasn't properly adjusted or the cam chain sprocket was wore. It could be improper valve clearances. It could be a bad valve due to improper valve clearances. Is the bike still under warranty? If not get a service manual check these items out.
It could be running on one cylinder due to a bad spark-plug too and the popping would be the other cylinder trying kick in again. I wouldn't ride it anymore until I found out what was wrong with it. Good Luck

Answer 3

Check the valve adjustment.
Tight of leaking valves would run OK, but have no power to accelerate.