Big Bore SX Mod???

**userj8670** · 03-05-2009, 08:53 AM

So i was offered the opportunity to buy a cylinder and piston and head off a 300 forman. Would this bolt up to my existing sx case to make it a big bore or is there machining involved and would it be worth it? I have a Rocky Dome piston that i was going to throw in before this deal came along and i want to know which is the better of the two. (yes i know its gearing limited but i dont care lol)

**honda250sx** · 03-05-2009, 09:13 AM

wrong will not work. stroke is different. already explored this avenue jimmothy. Why dont you just buy a trx300 and put it in. Then all we have to do is change the output shaft.

**userj8670** · 03-05-2009, 10:58 AM

Well find me one at a cheap price!

**honda250sx** · 03-05-2009, 11:05 AM

come on nancy. i can't do it all, all the time!

**The Goat** · 03-05-2009, 01:40 PM

400 or less on highlifter.com for a used 2wd engine.

**userj8670** · 03-05-2009, 07:00 PM

Originally Posted by honda250sx

come on nancy. i can't do it all, all the time!

DAM U and this NANCY!! We had this discussion at Mighty...or i think... i was still buzzin lol

**oscarmayer** · 03-05-2009, 08:56 PM

Originally Posted by The Goat

400 or less on highlifter.com for a used 2wd engine.

i don't see any motors listed.

**The Goat** · 03-05-2009, 09:12 PM

.......heaven forbid you have to do a little legwork and watch the classifieds in the forums right?

as a note to the post creator, they make big bore kits for the 300s ranging all the way out to 400cc... stupendous amounts of torque when combined with the low gearing of the 300.

There are also multiple gearing options on the 300...people swap out a drive gear and can get another 21% gear reduction.

**userj8670** · 03-06-2009, 08:53 AM

Goat,

now thats interesting to to know! Hey jeff I hope your reading this.... Maybe we can get these sx's to go faster...

**honda250sx** · 03-06-2009, 09:17 AM

I got a tri-z to go fast son. SX is my leisure ride

**KillerBox** · 03-06-2009, 09:50 AM

I wish someone would make and sell me a kit to change my 250 ES Big Red engine to a 300cc. I would be more than happy to buy something that was plug and play.

You all get way over my head and Us mechanically challenged people need all the help we can get!

**Nick_R_23** · 03-06-2009, 12:38 PM

Whats all involved in changing the output shaft? Does it require splitting the cases or is it a unbolt off one, bolt onto the other kinda deal? What about carb, electronics, exhaust?

Ive considered finding a 2wd 300 motor to swap into my Big Red, but if I can get a 400 kit for it that would be awesome!! Is 400 the biggest it can go?

-Nick

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Big Bore SX Mod???