Definition please for newbie

top end: That part of the engine that includes the piston, cylinder, intake, and exhaust

Bottom end: Mostly the crank, sometimes the transmission.

engine rebuild: usually refers to a top-end job (piston, rings)

Look up at the top of the page, near the User CP, for Motospeak That has lots of definitions for you.

Yep, the "motospeak" section of this forum is a place you really want to visit!

Here is a link if you can't find it above:

http://www.dirtrider.net/forums3/glossary.php

The most important things to do on your bike:

Clean the air filter. This involves washing it and re-applying the oil.

Keep the chain clean and oiled.

Change the oil OFTEN! The clutch operates in the oil and the abrasive dust that wears off the clutch is in the oil which isn't good for the bearings.

"Top end rebuilds", which can be just new rings and gaskets, new piston and gaskets or new piston and cylinder sleeve/hone/plating is a fact of life with high performance engines. Some of the "off road" model bikes that were not intended for racing will have engines that can go a long time without rebuilds, but the engines found on most MX bikes give up durability for performance and the rings/pistons will not survive for long. A common rebuild schedule for a bike used for racing is after 15 hours of use.

Note that it is a lot cheaper and easier to rebuild the top end before it fails than it is after it has failed.

Rod