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whats the best way to get power with out boring...i have a 300ex and i have it jetted stage 2 cobra exhuast system k&n airfilter no lid..what else could i do
 

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Boring dosent give you any more power.

If your talking about going to a big bore kit then yes it will give you more power. Boring is used whenever the cylinder has enough wear to be out of tolerance with the piston and rings, therefore losing compression. So you bore the cylinder to the next size. Boring the cylinder over to the maximum it can handle will probably only give you .5 hp

If you want more power out of the thing look and gettin a higher compression piston. wiseco makes like a 10,11, 12:1.

You can also look into getting a camshaft to change your power range. Dont get a high rev box you can rev your quad to 15,000 rpm but if im not mistake a 300ex stock cam makes most of its peak power by 5-7k rpm. so getting a rev box to let you rev till 10k rpm dosent do you any good either unless you have a camshaft that allows the engine to make power untill 10k rpm.



Realistically Id sell your 300ex and buy a 400ex. The cost difference would be minimal and you would be starting out with about 10 more hp.
 

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I Agree^^^^^^^^^^^
 

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You will get a much better ride out of a 400 also. The man to talk to on the 250X would be TRX2five0 he has done a crap load to his. basically what mdopole said.
 

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K&N lets in alot of particles. I wanna get some of those little filters that snap into the airbox lid whenever you drill holes in them, idk what they're called.
 

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Change cams.

I don't see how you figure boring doesn't add power? On a 400EX, if you bore it to the max on the stock cylinder it makes it a 416cc. That is not going to be a huge gain but it wil produce more power than a 400cc.
 

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what about a port and polish moteer bored 30 over and a 400ex carb and compresion of 10
 

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Change cams.

I don't see how you figure boring doesn't add power? On a 400EX, if you bore it to the max on the stock cylinder it makes it a 416cc. That is not going to be a huge gain but it wil produce more power than a 400cc.
I didnt mean it wont add power its just so innefective to the cost of having it done its worthless. After you buy a new piston and pay to get your cylinder machined you could have purchased a more bang for the buck part, like a camshaft, or taken the money to get some riding lessons that will make you a faster rider with the power that you already have.

By the time that tiny increase in power gets to the wheels you will not even notice it. You wont notice it on acceleration, you wont notice it on a time slip, you'll probably not even notice it on a dyno chart. Youll be getting like .2 horsepower at the crankshaft. Plus now you have the extra weight of the larger piston and rings and more friction in the cylinder due to the increase in size and more heat going on in the cylinder so you might actually lose horsepower.

Ask any reputable engine builder that actually straps his product on a dyno. They will tell you the same.
 

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I see what you're saying.
 

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When you increase the bore of a cylinder you are increasing the volume of of the chamber thus increasing power. stock bore is 74mm. true you won't see much of a gain at all but every little bit helps add that with a good cam some good head work and you will see a relatively significant power gain. a stock 300ex is actually 290 some CC's if you increase the piston bore and the compression size you will feel the gain. Mdopole you should know that with your 250X and the mods you have done to it. Most of the time if you are rebuilding these small engines you will find some irregularities in the cylinder walls, since these engines are air cooled and have a high RPM range, so boring atleast .010 or .020 is a must which anything under .040 you woun't see any gains that you can feel in my opinion. Most autos are punched out 10,20 or 30 thousands to remove cylinder wall egging which is very common in fords by the way. You want power from a small engine ?? put a stroker kit in it. I have seen 5hp Briggs engines on Mini- dragsters run 80Mph in an 1/8th so I know we can mod these 250 or 300 engines to run competatively, but you better have a deep pocket.. lol
 
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