I have been riding a stock 300 for long enough. I think I'm ready for a big step up. I'm lookin for a big bore kit for my old stock 300EX. I need help about if you anybody who has these performance kits available for my honda. I know some aftermarket companies have 330c kits for it but I'm not sure who. Ritter Cycle Racing makes customize engine kit that brings it up from 282cc to 352cc and the starting price is $1100. I saw a pic of a 300 that was said to have a 395cc kit in it. Then I saw a 300 with a TC Racing 405cc kit in it. I just wanna know how much this engine kit will cost from each of these companies. Also, does Four Stroke Tech or Curtis Sparks make a big performance kit for this quad? If so, how much??? I'm just in the developing stage at this point. And I'm very curious. I'm a teenager and I'm ready to start a motocross career but I REALLY need come mods to wake up this small sport quad. Any replies will be appreciated. Thanx

 

I have what started as a 300 ex and four stroke tech did the full race motor kit to it that included, big bore, stroke, porting, big valves, carb, exhaust, rev box mod, remove 1st gear and reverse. and more that I can't think of right off. It cost $3300.00 whan it was done.
it is a very good running motor, but, I would not recommend it for anything but racing, My suggestion would be try a cam, valves, porting, and hihg compression piston with exhaust and carb
try to leave the stock bore and stroke if at all possible

 

I belive that White Bros. Makes a "Kit" to make the 300ex (actually 282) a 302. The kit I think had the piston, cam, exhaust, filter and some other little stuff. You use the stock cylinder and sleeve, no need for resleaving, but I think its all the boring that can be done, so if you blew it up, it would have to be resleaved.

 

TC 405 kit is around $2500-2700 motor work pipe and carb

 

Take that cash and buy a used 400ex.Then you will have a machine worth building up.Why put all that cash into a 300???You will be much better off in the long run.

 

Unless he just likes his 300ex, or maybe he runs the 4-stroke class.

To each his own. I got rid of my 300ex for a 250r and havent regretted it for a day, another friend did the exact same thing, took the R to the track one day to practice and has been for sale ever since so he can get a new 300ex.

 

I plan on adding a TC 330 kit too my motor over the winter. With my current mods, it will boost HP into the mid 30's.

One word of advice from a racer..... "Power is nothing without control..." You may want too add some aftermarket tires and shocks too that EX before getting into the motor. You will thank yourself in the long run.

Here is some info for you.

TC Racing (814)723-3514
Four Stroke Tech (814)842-6159
Powroll (541)923-1290
Rick Ritter(618)664-3211

Call them, and tell them what you are looking for. All good engine builers will work with you, too find what works best for your needs. If they don't, they don't deserve your money.
You will find that their prices and advalibility are all about the same. Quality and customer service can be another thing. But I wouldn't get into that.....

 

call tc racing man they will hook you up with a national kit that will smoke the competition i read up on this company they build 95% of the top racers in the 4 stroke division...they build jeremy shells winning 300ex...and you wont lose reliability as you would with a big bore kit..i think the national kit pumps out 45 hp..compared to stock ex 18hp..thats a huge difference..according to Tom Carlson of tc racing the 250/300ex motor is the choice for racing the motor itself has potential above and beyond..he also has a kit that will turn your ex from 5 speed to 6 speed..this dude is phat man...give them a call i think the national kit is like 1500 bucks and if you dont want to spend that much then you can mix and match to what you can afford..his shop is in Pa...and he is like only one of the remaining 4 stroke guys that is more into 4 strokes than 2...i have the number but not on me if you want it email me and ill give you the number...but seriously give them a call..