Changing the transmission oil in a Tomos A35 engine
One 13mm open ended wrench
#2 Phillips screwdriver
Small funnel (Type used to fill camping stoves or equivalent)
ATF Type A, Suffix A (Many Dexron fluids are Type A, Suffix A compatible. Check the back of the bottle to confirm. I was able to find Tech2000 Synthetic ATF at Wal-Mart for under $5 per litre.)
Oil Changing Procedure
Take the moped out for a short ride to make sure that the transmission fluid is hot. This will lower the fluid's viscosity and allow a greater percentage of the dirty oil to run out of the crankcase.
Place the moped on the centre stand and place a 9x13 cake pan or other suitable receptacle under the crankcase. Turn the moped off.
Remove the right side cover. To do this you will have to remove two screws. The first is a small Phillips head screw that is found in the induction cowling, the second is a larger Phillips near the crank arm.
With the side cover removed you will now be able to see the carburetor and air box. Using a slotted screw driver, unscrew the "jubilee clip" like clamping ring that connects the air box to the carburetor. Using a Phillips screw driver, remove the screw that fastens the air box to the frame. Slide the air box boot off of the carburetor and pull the air box out of the port in the frame. With the air box removed, you now have access to the oil inlet port.
Using a 13mm open ended wrench, undo the hex head cap screw that plugs the oil inlet port. Likewise, on the bottom surface of the crankcase, a second cap screw will need to be removed to unplug the oil outlet port. Remember, since this screw is upside down, you will have to turn it clockwise, as viewed from above the bike, in order to loosen the screw. It is very easy to strip the crankcase if you turn the screw in the wrong direction. Finally, a Phillips machine screw can be found approximately one quarter of the way up the side of the crankcase, remove this screw to expose the checking bore hole. (This is also the screw you remove to confirm the oil level between changes.)
Let the dirty oil run into the drain pan. Using a small funnel, pour approximately 100 ml of ATF into the crankcase to flush away any remaining residue. Replace the drain plug and slowly fill the crankcase with ATF until the fluid dribbles out of the checking bore hole. Replace the Phillips screw in the checking bore hole as well as the inlet plug. Wipe away any of the ATF that has spilled onto the crank case and especially the exhaust.
Replace the air box and side cover.