[Good Vibes]

My bike emits a loud knocking noise when starting off up a slight hill, even using only 1/4 throttle (as still running in).  Sounds like piston slap although a friend thought it might be pre-ignition that can be damaging.  I changed to a higher octane petrol that can reduce pre-ignition but made no difference.  It only occurs at slow speeds and if I ease right off it stops, but I don't like the sound.  I didn't have it on my 500 Bullet that I bought new so am surprised at having it on the GT.

Has anybody else experienced that knocking?

[ace.cafe]

Take it to the dealer immediately, and get it checked out.
If it is detonation, it could be harmful in a very short time.it shouldn't be doing that. The warranty is there to help sort out things.

[Good Vibes]

Thanks Ace, our NZ dealer is a full days ride away, but is really helpful, and yes all covered by warranty.  I am going to try to record noise for him, bit difficult when moving, but will give it a go.   

[burtial]

Could you just be lugging the engine at low RPM's?