how can i make my 3ooex faster without spending a lot of money?

 

change the gearing,but you will lose some bottom end.

 

is there any thing else i can do

 

i want to make my 300 beat my dads 400ex?

 

Pipe and filter will help, then it can pull taller gears,but you will only be hitting about 55 mph or so, to keep up with a 400ex, you are looking at a big bore, and cam to stay with him, but that will be pretty iffy. The money you would spend to keep up or beat a 400ex would be better spent buying a bigger quad. There is only so much you can do with a 282 cc motor.

 

You will have to let the air out of the tires on the 400ex ,pour rotten gas in the tank,and adjust the throttle so it only opens half way . That the only way a 300ex will beat a 400ex for not a lot of money.

Otherwise a 352,406 kit,major porting,big valves,big carb,exhaust,cams,(around$1500to$2000) will get it to beat a stock 400ex.
With that power you will need to throw a lot of cash at the suspension to keep the tippy 300 on its wheels. All in all keep it stock , get a 400ex or the many faster quads and save yourself the trouble.