Help wanted! Generic TR 125

[ChinaBike...]

Hi Gents,

We need support on our Generic TR 125 Supermotobike which we unfortunately can not get from any Generic Motorbike Dealer around.

The bike was driving ok for some 100s of kilometres. Then my daughter complained about losing power.
I checked the engine and found first bad compression and then a bad piston, cylinder and cylinder head with worn valve guides.
I repaired the mechanical parts of the engine with new piston and cylinder and had an overhaul of the cylinderhead done. Put all back together. Made sure that timing is perfect and all is in great condition.
The engine now starts very nice and easy and keeps low idle very stable. while standing you are able to rev up the engine and all reacts very nice and smooth.

But... now when you are riding the bike it really starts nice and powerful but after a couple hundred meters it completely looses power and turning down until it completely turns off... After this happens it for several minutes not possible to restart the engine. I tested the spark plug during this period and there is a strong and powerful spark.

Since we are having a second (broken) bike of the same type I tried several spare parts. Temp sensors, all sensors and potentiometers of the throttle valve body, injector, ecu and fuel pump.
With every single replacement - no change in the behaviour...

any further ideas what the issue could be? Please. we need help. Summer is coming and my daughter would love to ride her bike again...

Thank you for your support!

[humanbeing]

What's the reading from ECU? http://www.chinariders.net/showthread.php?t=14758
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Shop manual: https://shop1897.hstatic.dk/upload_d...ice_manual.pdf