Honda cbr125 r misfire

[Wright13]

Hi I am loosing the will to live with my cbr125 r 2004
It's on a grass kart so no longer in a bike
The problem is
It starts fine and ticks over even from cold but from about 2/3rds throttle it becomes possessed!!!
It starts to chok up splutter and cough and cuffs out fuel from mouth of carb
It's been bored to oversize +1
It's had all this new:
Diaphragm, inlet valve, coil, Ecu, plug, battery, wiring
Carb has been stripped and cleaned a 1000 times
And even used two different carbs and it still does it
Apart from costing me a fortune it's driving me nuts
Any help would be great
😡😡😡😡😡😡
____________________
Steve wright

[Robby]

It's been rebored, so the timing has been disturbed. Having the timing chain out by a tooth could cause it to spit back through the carb.

I assume you're also not running with the standard exhaust and airbox. On some bikes, these are absolutely vital to get it run right at higher power outputs, due to the kind of maths that feel more at home in designing an opera house than designing an engine.

Check the timing first. This is assuming you haven't got some kind of really nasty lash-up wiring which is failing either under electrical load, or under vibration.