I am looking for more power and throttle response from 300ex. Wut would be some good mods without tearing into the engine? If I do tear into the engine wut should I get first?

 

You could put an aftermarket pipe, jet kit, filter, remove the lid without touching the engine. As for the engine mods, you could start with a piston or a cam.

 

If I put an aftermarket piston or cam will I need to get heavy duty clutch springs ?
Will the stock clutch handle the extra power ok?

 

I don't know. A 300 isn't a big mill anyway so probably....

 

wont i get way more dirt and water into the airbox if I remove lid

 

I took my airbox lid off my blaster and haven't had any problems. Just be sure to check it regularly. Get a uni filter too.

 

You can mod the air box lid by drilling holes and putting foam plugs in to keep dirt out, or you can buy an Outerwears cover that velcroes to the top, no lid, but keeps dirt and water out way better than no lid (you can specify waterproof Outerwears) If you run with no lid, you will need to go up several sizes on the main jet, to make up for the greatly improved air flow. Just a pipe and Uni filter on my son's 300ex (lid on , went up one size on main and pilot jet) and it made a big difference, the stock pipe is very small and restrictive.

 

will I have to just go up sizes on the main jet?
or will I have to change the leval the neddle is at?
Do I have to change pilot jet?
Why usually when you get a pipe and filter you have to go up just on the main jet size?

 

Yea you gotta get an aftermarket pipe and silencer on that EX even if it's a cheap-o DG it will make a difference. Also maybe look into a gearing change. You could change the sprockets very cheap to get you either more top speed or more low-end your choice.

 

Rippin, any time you increase the air flow into or out of a motor,like with an aftermarket filter, taking the lid off, or an aftermarket exhaust, you increase the amount of air the motor takes in on the intake stroke of the piston, because you remove the restriction coming in or going out. The 'perfect' air to fuel ratio is about 14 to 1 air to fuel, you need to put in a bigger main jet, or move the needle clip, to maintain that ratio to keep your engine from overheating,pinging,or wearing prematurely. best thing to do is after the mods, jet up until it sputters on the top end, (too much fuel at wide open throttle) then drop one size. A final check is a high speed run on a new plug, then kill the motor, coast to a stop, and pull the plug (owww, hot !!!!) to check the color. You want a nice even brown or tan porcelain,not white or black. Hope this is some help.