hey guys. i have an RB T9 in my 733 and i took it out the other day to inspect it. so i removed the backplate and had a look. the crank for some reason is very brown in colour and has like little black carbon spots on it, there is also a bit of end play in the rod. but this seems very wierd becouse the engine has only gone 2.5 liters of fuel. does anyone know the answers to these small problems. thanks bugers

That brown colour, and black spots happen when you leave fuel in the engine.

After completing the day, remove the fuel tube which goes to the engine, and try to start the engine several times more, to burn the fuel which is left inside.
Then remove the glow plug and air filter, and apply a couple drops of after run oil, install the glow plug back and turn the engine little more to spread the oil.

A little play in the rod is normal, especially if you didnt change it after break in. Try to change the rod after break in+ 1-2 races.

but i always made sure i put after run into the engine after a run. i would always put 3-4 carbs of after run in and spin it on the starter box. also do know if this would cause premature pin failure?

Mate get some good quality after run oil ,like RB ,mugen or exceed .and make sure you burn all the left over fuel out before you oil the engine .
If you are using alot of oil then you will need to get rid of some before you restart the engine as it can place to much load on the piston pin.a few drops is all you need.
As far as rod wear you should replace the rod after run in .
Running to lean can also cause crank pin and rod wear.
To keep your engine in good condition you should replace the rod & front bearing every 2-3ltrs and the rear every 4-5 ltrs.