EC300 2018 Knock on steady revs 🤦*♂️🤦*♂️
 

Hi, i have a GasGas EC300 2018 and when i go with steady throttle, lets say, 1/2 throttle i heard a knock sometimes, not a sequential One like a rod bearing, knock knock knock, it sounds different, but it really pisses me off. When on stand and you rev it until half throttle it does the same. When idle it sounds pretty normal and when i go full throttle its good too. some friends said that is normal on 2 Strokes but i don't think so.. do you have any idea? Usual problem? Use RON98, mixture @50:1. The top and bottom end are new, 10hours.

Every GasGas that I've owned has that noise.

Chain slap? This was a characteristic of the older GG models. Sound comes from down low (swingarm), so it can be masked as engine noise.

Power valve making a transition at 1/2 throttle (but this is engine speed dependent)? You said new top end? Possible that something came loose in the PV mechanism, and the power valve is flapping around? That could cause a rattle.

Chain is on spec.and it happens when i have the bike on stand, it definitely came from the motor. Already checked the PV and its ok, nothing loose..

Theres nothing that i can do to stop it?

Not really.
Can you post a video with the noise?

It could be pipe bang from unburnt fuel in the expansion chamber. But this usually occurs on deceleration, or rolling off of the throttle.

It could also be noise from the clutch assembly. I agree with gasgasman that all of the Gas Gas bikes I have owned make some knocking noises, which typically goes away when you pull the clutch lever in. I notice it most at idle, but hear this when rolling on the throttle as you describe.

I would not worry about it unless you are showing signs of pre-detonation or that the bike is running lean.

Post up a video..

bad engine
 

Been on gassers for many years familiar with noises . Seems to be lots of issues with 18 up bikes .Mine has a bottom end knock havent pulled it yet but i believe they did a crappy job building or cheaped out on something on the newer bikes . Don't trust it .

Check the flywheel nut. Mine was loctited but was not done up tight against the flywheel. There was also a recall on the right hand crank nut.
Failing that you may have too much compression and need some head modifications. Mine was knocking under load slightly no matter how it was jetted. The head was machined to lower the squish and drop as much compression as possible. Smooth predictable power now with next to no spooge.

The chain buffer (slider thingy) on the swingarm is made of a very hard plastic. And so at a given rpm/load the chain can load and unload to slap against - this is even with the chain adjusted correctly.

If you are right at the threshold where the pv valve with open/close, then it can flop between open and close and be heard.

jeff