Liam you have a problem for sure. Your valve is currently doing the exact opposite of what it should when set up correctly.
I am almost certain this has happened because you’ve always stored the kart with the cover and compression spring on. The green below develops a “memory” from being in the closed position for extended periods.
You need a new bellow (the green rubber piece). Get one of these and rebuild the valve.
Go on YouTube and type in “rotax power valve” there are at least 4 videos showing you how the valve should work when set up correctly.
Also remember what I said about aligning the gasket with the little hole in the power valve housing. One other thing, make sure the curve in the blade faces downward when installed into the slot.
Hey Liam, without looking at the rest of your carb set up it is hard to say for sure but if the carb is set up correctly otherwise then yes, 170 seems to be quite rich.
Where about in the world are you located? What is your altitude and current temperature? What oil fuel ratio have you been running the engine with?
The plug is excessively rich, the jet chart should only be used as a ball park guide. Many different things affects jetting beside that the chart is catering for.
You should probably be on a 162 or so I reckon but testing is the only way to know for sure. Make sure you’re running a IW24 plug. Drop jets until the engine starts “popping” then go back up one or possibly two…decide on that based on how strong the engine feels along with the stop watch.
But I must warn, before you start undertaking the task of jetting the engine for maximum performance, all other items maintenance wise need to be in check. So PV, carb setup and cleanliness, fuel pump, exhaust sealing and matting
