VBB2T detonating at full throttle


My VBB2T starts to detonate when I drive 75-80km/h or more.

I checked my ignition which is 28° TDC, point gap 0.35mm, sparkplug L86C (=NGK B6HS).

Fuel 98oct

Tried with colder sparkplug L82C

Would it help to change main jet to higher type (102-104)?

Sparkplug is light brown, would like it to be bit darker.

Any ideas?


Hi dude


Do you dirve the original engine ?