Anyone knows what this sound is - detonation?
 

You can hear it in the video as I apply throttle out of the corner: (advance the video to 12:50) https://youtu.be/zYy1NkgNCfE?t=771
It sounds like a vibration / rattle. It's not hugely intrusive, but it's one of those things as a rider you notice. I thought it was the muffler end cap (it loosens as the muffler heats up, and vibrates) but I'm certain I only hear this noise under load.

My bike's done this from day one, irrespective of ambient temperature. I did think it was just the bike's character, but since looking into carb tuning and watching a lot of videos on the subject, I've wondered if it's spark knock / detonation. It happens in any gear, often in the same rpm range (hence it may be mechanical) I do run 87 octane (I usually don't bother with premium unless the manual specifies it) and will try a higher octane fuel next tank.

Bike runs great, very smooth, I'm just fearful of detonation if that's what it is.

It sounds like a sympathetic vibration of some component on the bike, to me. But yes, try a tank of 91 octane to see if it goes away......ARH

I know my Hawk requires 90 minimum.

Ours had a similar sound. I thought for sure it was either the air pump actuating under load or something in the motor. It only showed up sometimes, under certain rpm's and loads.
Ended up being the right side tank plastic wing that I discovered completely by accident.
The rear clip-on mount needed to be bent in a little to hold the wing tighter. Tap on both plastic wings toward the rear and see if you can replicate the noise.

check the spark plug, look for black specs. ie salt and pepper.

detonation will remove particles of carbon from the plug, and even add specks of alluminum from the piston if its bad enough.


the bike sounds like its running decent. lean it would run like shit.. can you feel that in the performance of the bike?

detonation is often accomanied by a missfire that can be felt.

Sounds normal to me. Pushrod motor, naturally sounds like a bag of bolts

Thanks all. On the ride into work this morning I listened hard and I do think it's just engine 'character'.

I had this exact noise occasionally when throttling on mine at first but it seems to have gone away, either on its own or from removing plastics/tightening fasteners etc throughout doing maintenance. I believe it was definitely more of a vibration coming from somewhere than a knock. Make sure all your plastics and motor mounts are snug :)

Oh, push rod buzz. I hadn't thought of that. Definitly a possibility. How's that for a definite answer!

bag of bolts? my pushrod cg200 sounds like a sewing machine.... :hehe:

https://www.youtube.com/watch?v=oymf0rP30TU

i found mine to be the lock cover on the gas cap vibrating ... you should not need high octane fuel in a bike with such low compression though

This was my thinking. The manual states 87, and I reckon the bikes are engineered to run on poor-quality fuel if necessary.