Engine swap?

[4x4_war]

i have a 95 trx 300ex, and was wondering if anyone had a 450 r engine for sale? and if it would work in my 300ex, or if i could trade for my 300ex engine. it's bored out, but idk to what extent. I just think that it would be fun and cool to go up next to some guy or a friend with a predator, or a bored out 300ex and have him think im riding a 300ex when i have a 450r engine in it. thanks!! i know that i need to bore it out to beat a predator, because they're 500cc. btw

[deathman53]

you can get a yz426-450f motor in it no problem , maybe a crf/trx 450r motor. I will ask you WHY? You will need alot of fabrication for it to work and you are still stuck with a chassis that can't handle the power those 426-450 motors make. Unless you already have extended a-arms, better suspension, better brakes, ext. axle and extended rear swingarm, you are wasting your time. To do the 426-450 swap, you will need a radiator, change the frame to CORRECTLY fit the new motor, modify the swingarm for the motor, re-work airbox setup and other little stuff. The cost will add up fast. A better option would be a 85/86 atc350x motor, better would be one thats bored/stroked to a 432, it almost looks factory, nearly bolts right in, your wiring works(with some modding), the only thing would be a exhaust(you probably can modify a 400ex system to fit). It will have more power than you know what to do with.

Another option is to sell the 300ex and buy a 450r, you can get one for ~3g's and it would be fairly tricked out. You will have 3 grand into the 300ex hybrid and still be stuck with a bad chassis. Remember, the motor isn't everything on the bike, you need suspension and chassis parts that work together to get the power to the ground.

[tayyo789]

I wouldnt use a 300ex at all for a hybrid. go with something bigger, with better handling and suspension. sell the 300, and get something bigger. even a 400ex. you can get those for fair prices, and if you want a hybrid later, you would already have the chassis

[4x4_war]

Originally posted by tayyo789
I wouldnt use a 300ex at all for a hybrid. go with something bigger, with better handling and suspension. sell the 300, and get something bigger. even a 400ex. you can get those for fair prices, and if you want a hybrid later, you would already have the chassis

well i want something i can throw together for more quick, cheap power. i am considering buying a 350x as mentioned by the first response. if anyone knows where i can just get the engine, for little or nothing that would be great. i am boring it out, so idk the ecxeptions for that. but anyways thanks for the replies!!

[deathman53]

A good rider doesn't need to bore a 350x motor. Besides people think that by boring a motor to the max they are making bigger power, they aren't in real life, nor big jumps in cc's. Lets take a 250r here, its 246 in 66mm bore, the max is 270(140 over). The difference isn't all that great, it just wasted the bores left in cylinder. Going to a big bore sleeve is a different thing completely, usually those are accompanied with cam, head porting, carb mods and such, so the real difference in JUST the big bore isn't that great. As I said before, you need to put the power to the ground to get the most out of the motor. If I were you and dedicated to keeping the 300ex, get suspension that matches your riding/weight, replace worn bearings, get newer/better tires and refine your riding skills from there. A new clutch can make a huge difference in a motor. It makes a huge difference and NO a gutted silencer DOESN'T make more power, it just makes more noise and less power(loss of backpressure).

If you go with the 350x motor, suspension, tires and such and still think you need more power, send the motor to get re-freshed(just bore to clean the bore) and ported, along with a cam and such, fcr 39 carb and new clutch. You sound like a younger person who believes in myth's. You can put a pro on a stock bike and he/she will blow your mind away. I seen it myself 3 times. My friend was riding my 250r(nowhere near stock) and hanging with John Natalie the whole time, I couldn't hold a candle to Natalie. Natalie's wife had a pretty stock 450r, she blew away alot of the riders. Its 80% rider and 20% bike or something close to that.