What would be a good thing to do? What do you guys think i should bore it to... .20, .40, .60, .80? I don't wanna bore it too much and i'm not sure about a big bore kit because of reliability? I just want more power. any help?

 

Hey 300exking

Instead of boring it any don't you just try a higher comp piston and a cam because when you bore your stock sleeve your just making it thinner thus less reliable.
Most big bore kits come with a lager sleeve which is alot more reliable because you're not making your cylinder walls any thinner your just increasing displacement which is a reliable way to get more power.

The biggest problem with big bore kits and boring your motor is jetting the carb so the motor is running right.
I'd say your best bet is to just buy a bigger carb, a high compression psiton and a web cam, that should give u a noticable power gain.

 

With the high compresion pistion can i run pump gas?

 

As long as you don't go to high. I ran a 10.25 to 1 on the quadsport and ran 87 with it no problems.

 

300EXKING,

I would say that with a higher compression piston, Web Cam all-around grind cam, full exhaust system, jet kit, and a good filter, your 300EX will really wake up.

The 300EX really likes a larger header. More so than some other machines. The higher flowing silencer will help as well. The higher compression piston should help out quite a bit too. Now, on to the cam. With a cam, you will have to lose a little power somewhere in the powerband to gain it somewhere else. Probably, with normal riding, you wouldn't want anything more than an "all-around" cam. The jet kit and higher-flowing filter will help the machine get the air and fuel that it needs. I hope I've helped you out.

 

High compression piston or big bore = more heat = getting an oil cooler.Even stock I whould get the oil cooler.Go with a 10.5:1 drop in or.040 over 11:1 max,W/B or WEB-CAM all around cam and with the cam degreed in you will gain power everwhere.Get o/s intake valves,mild port job or clean up,400 carb if you can get one cheep.

 

i would check out www.sparksracing.com if i were you. i don't know of the selection he has for the 300ex but he has a good selection for the 400ex.

 

In one of the posts above he said to get a bigger carb. Which carb is the Awesome! one to go with that you will notice alot!!

 

In my opinion, if you are going to spend the money for a high compression piston, full exhaust, carb and cam, you may as well spend a few extra bucks and make it a 330.
I was just reading through back issues of Dirtwheels last night and read an article in which they tested a Fourstroke Tech 330ex vs. a Stock 400ex and the 330 would even outrun it in a drag race!
The kit from FST comes with the sleeve, piston, valves I belive, valve springs and oil cooler. Then just get a pipe and a cam for an extra $350 or so and you are gonna have a WICKED 300ex!

 

I think some people on the forums have the 330's. Ask those people what they think. Sparks should certainly be able fix you up with some awesome modifications. Good luck.