Don’t know if any can help but I have a 2017 TRS RR that runs bad when hot. I ride for around a hour then the bike feels different with a loss of power and sounds slightly different like a spluttering sound.

I have cleaned the carb

changed the o rings in the cylinder head as my coolant was think and a grey colour 

new spark plug 

Probably need to check your oil and pull the water pump apart and look to see if it has leaked into the oil.

CDI box

Today I was helping a friend track down the source of the same symptom, bike ran and started poorly when it got hot.  On disassembly it turns out the piston is badly scored near the exhaust port and small bits of piston literally welded itself to the cylinder wall.  Bike is a 2022 model with only 150 some hours on it.  We didn't see anything to account for the damage so far such as foreign material and the damage is limited to where the exhaust port opening is.  

In retrospect the piston damage would have been visible to inspection by removing the exhaust header only.

In late 2023, I investigated a hot running issue with a friend's low hours 2022 TRS 300. It ran poorly when trail-ridden once warmed up.

I found some things wrong.

1 the coolant level was very low. From memory it took something like 300 ml to get the level up where the book says.

2. The fuel filter inside the fuel tank was restricted by debris.

3. There was way too much sooty carbon on the piston crown and inside the head for the hours it had run.

4. I found something that I don't know is wrong or not, but seemed odd to me. It had both a resistor spark plug and a resistor spark plug cap.

5. The reeds had wear marks from touching the open stops.

I found out that the owner had been using Castrol 747 premix oil (the one with some castor oil in it).

I de-coked it.

I cleared the fuel flow restriction.

I fitted a non-resistor spark plug.

The owner then ran it on semi-synthetic premix oil.

It ran fine.

The reeds are going to be replaced soon.

I suspect the running issue was being caused by the engine running hot due to lack of coolant, float bowl level going low due to fuel filter restricted and too-high compression ratio due to carbon build-up.

 

4. Is totally normal.  RF interference can mess with digital ignition so this belt and braces approach subdue interference level.