I have a Mazda RX-8, 231 brake horsepower rotary. When I turn it over, it takes ages to start up. I changed the battery but it didn't resolve the problem. When it's running, it doesn't have an issue, it is fine. Should I be looking at the starter?
You say it starts. If it cranks normally then it is not the starter. But if it turns to a normal speed and it starts out driving normal, with a continuous rapid starting sound then that means the starter is okay.
But now, if it has a slow, unusual starting sound, then either the battery is weak or the starter is starting to wear out. But, if it cranks at a normal speed, those rotary engines are notorious for their Apex seals.
They don’t have piston rings because they are not piston engines. They’ve got these three Apex seals on each corner of the triangular rotor and they will lose compression and be harder to start as they age. So, do a compression test first. You might see that the engine is starting to wear. I see that a lot.
Of course, tuning it up would also be helpful in this case. Put new spark plugs, a new air filter, and a new fuel filter to make sure it is tuned up right. But, if it still does it, a lot of times it is just a worn-out engine on that model.