Hints & Tips...
SUSPENSION
Don't ride your bike with dry mud on the chrome fork legs wash it of before riding, the dust seals will not remove hard dryed mud it will pass under both dust and oil seal damaging both and possibly guide bushes also.
If you have a leaking fork seal try using a seal mate or similar tool it may be just a small bit of dirt trapped under oil seal lip, if it persists then you will need a service .
Let the air out of your forks before every ride from bleed screws, If they are air forks check which is the bleed and not the air spring.
On most forks and shocks slowing or speeding up the rebound has an effect on the compression but not in reverse.
Don't ride with twisted forks it will damage your bushes really fast, straighten them out soon as poss at end of the race or when you get back to the van. If practicing don't ride the rest of the day before sorting them out.
When changing front wheel dont push fork feet together on axle it will damage bushes a forks will feel stiff, let right hand fork foot find its own place, bounce the bike before you do up the clamp bolts on the foot.
ENGINES
Spark plugs need replacing in four stroke engines just as often as two stroke engines.
After every wash on bikes with a carburetor the drain bung should be removed as most will have water and dirt in.
Don't run bigger valve clearances than the max clearance given thinking that it will be ok and never need looking as often, it gives the valves, buckets and cam a really hard time and may cause damage. We have had bikes in with 1mm and more clearance. Plus it rattles.
Don't think if your bike runs a 10w 40 engine oil that it will be better protected if you change to a 15w 60 oil. The oil viscosity is chosen by the manufacturers according to the engine piston and bearing clearances, The wear and scuff protection additives are not related to oil weight.
If you run a very high tick over on a four stroke they are usually harder to start when hot.