help on 300ex

[PsychoX]

i wanted to know what thing i could do to my 300ex to make it ...ALOT faster or if a 350x motor or perferably a 250r motor will bolt into it?

or what is the best big bore for the 300ex's thanks

[OldSchoolin86]

Best big bore is a 330, best bore and stroke is a 352. I've built a couple 250x/300ex motors and you're way better off selling and buying a 400 or a 450. The 350x motor does fit with ease but you're still no better off then just buying a 400ex. If you did the 350x swap you'd need a custom exhaust.

[PsychoX]

yea i dont have the money to get a new quad , so i was looking for the cheapest mods

[PsychoX]

also what do you think the cost of those things would be?

[OldSchoolin86]

You're looking at about $1200-1300 for a good 352cc motor and that's if you can do the wrench time. That's why you're better off selling and buying a 400.

[PsychoX]

well thanks for the help but that seems a bit much

[Lots_Of_Nothing]

well thanks for the help but that seems a bit much

Well, Lets look at your other choices..

350x motor.. A good running motor goes for around $500-$800, Then you must buy the complete wiring harness, kicker, shifter, carb, all that fun stuff. Then you must buy a custom exhaust (a few companys offer the exhaust kit for a couple hundred). So at the end of that, your looking at $1200++

250R motor? Well, a good running R motor goes for around $450-$700 (stock motors). Then again, you must buy all the wiring, kicker, shifter carb, etc. and then somehow cram a pipe for it in there. Of course you would then have to deal withmounting it, and the radiators, etc. I'd say with that your again, looking at $1200+++

The same goes for a big bore, really pricey, and it takes away alot of the reliability.

As Oldschoolin allready said. You are better off buying a 400 or something different.

Sell your 300, save up some cash for a bit. then buy yourself a decent machine that suits your needs.

[firefirefire90]

sell the 300ex and but a ATC250R!

[okieRrider]

Then part out the atc 250r and buy a nice quad.........Chris

[250r'en +TCB]

^^^ WTF?????????????? Are you on CRACK!!!!!

keep the 250r, you will scream by 400ex's all day long...

[max]

I Put A Lrd Full Exhaust/jet Kit/k&n On My 02 And It Made A Very Substantial Difference. 500 Buck For Everything. If Your Budget Is Tight And Your Planning On Keeping The Bike These Are The Easiest And Cheapest Mods.

[brapp]

Sell It To Me And I Can Try And Find You A 400 Or Somethign Along Those Lines If Thats What You Want?

[okieRrider]

Mines already gone to the four corners

[PsychoX]

well thanks for all the help everyone

[Modded660R2fast]

I have a a 300ex with the folowing mods that made it quite quick. Fmf full exhaust, k&n, jet kit, High comp piston, rev box and cam. They all made it almost faster then a stock 400ex. They all cost me around 600 bucks but i put them all in. When i race my buds 400 it kind of close. if we race around the back field then its close and relatively even but in a drag he only beats me by about 3 bike lengths.

[350Xhilaration]

andrew, check with Speedbump. He did a conversion 350EX and loved it. Made his own exhaust.

You can pick up an entire 350X for less than a grand that might need bearings, plastic and all the other stuff, but the motor might be good enough. It will have the harness and cdi too.

I could whip on his 300EX like a red headed stepchild til he put the X motor in it.

I wouldnt spend a dime on the 300(282)EX too wimpy stock and it takes way too much money to make them fast.

[Tecate performance]

if you want to stick with the 300 motor, you can go pretty far with it. i put a 380 bore kit, cam, o.s. intakes, and fcr39 in my buddies 01, and its holding up fine after 2 years. it runs with piped and cammed raptors, and 400ex's need a 440 or a good running 426 kit to hang. good torque with a strong midrange and overrev. TC used to build them to 425cc, and ran it in the open class in TT with banshees etc. it wasnt' the fastest, but was competetive with them and handled great for TT. he claimed 55hp at the wheels.

[Mosh]

well thanks for all the help everyone
bore it out to 50 over run a wiseco 12-1 piston. find someone to port the head. that really wakes up a stock 300 ex. install a cam and springs and a pipe.do it in stages. it will be cheaper that way. start with the pipe and jetting. than do the piston and bore. then do the cam and porting. each step will run about 300 on average. but you can do it in stages to save some cash. still you will have 1000 bucks in the motor.dont even think of a 250 r motor in the 300. there is no way it can fit. trust me. plus it will have so much vibration you wont be able to ride it.

[250r'en +TCB]

But after you do all this crap, spend all this money, guess what, you just took away the engines bullet-proof reliabilty!!! Iown a 300ex, they are nice machines for trail and somebodys first performance quad. But they are not 450r's or 350x's!!! you can't compare it to those machines because thats not what it was built for. It is an awsome machines that serves it's purpose! Sure after you ride a 250r or a 450r it seems weak, duh!!!
If you want to amke you 300ex go really fast, sell it and buy a 400ex! Why turn the thing into a time bomb and dump a ton of money into it? Just buy a used 400ex and make some minor mods to it. Same money, WAAAAAAY more reliable!!!

[TimSr]

As Oldschoolin allready said. You are better off buying a 400 or something different.

Sell your 300, save up some cash for a bit. then buy yourself a decent machine that suits your needs.


The 300EX's are worth more than 400EX's right now. You wouldnt need to save. Sell it, by a 400EX, and have gas money left over. Last year, brand new 300EX's were selling higher than 400EX's. When the 450's came out, the 400's tanked in price. There is no mbetter time to take advantage of it.

[Mosh]

But after you do all this crap, spend all this money, guess what, you just took away the engines bullet-proof reliabilty!!! Iown a 300ex, they are nice machines for trail and somebodys first performance quad. But they are not 450r's or 350x's!!! you can't compare it to those machines because thats not what it was built for. It is an awsome machines that serves it's purpose! Sure after you ride a 250r or a 450r it seems weak, duh!!!
If you want to amke you 300ex go really fast, sell it and buy a 400ex! Why turn the thing into a time bomb and dump a ton of money into it? Just buy a used 400ex and make some minor mods to it. Same money, WAAAAAAY more reliable!!!
400ex is more of time bomb than any 300ex,even built. most of them have been ragged to hell and back. heck, my 250 x with pipe can run in the trails with any 400ex.