If I were you, I wouldn't bother with the swap. Do a couple mods to your 300ex and it will wake up. OK, I'm going to get ripped for saying this but, if a stock 400ex puts down 27hp...I don't think so, none that i've ridden. It's fairly easy to double your 300ex's 16 hp without making it into a time bomb. I've been running a 330cc 11:1 compression motor for a year, and haven't had any trouble with the starter. I think the engine builders like the 350x because it can be bored to incredible sizes, something like a 452cc's? But you have to be a proffesional wrestler to kick the bitch over.

 

Sorry for not replying, been on vacation

To the guys that say go 400, i'm not giving up reverse, i ride on way too many TIGHT trails to lose it.

I'm thinking about just going TC racing. As soon as i get this piece of **** running!

 

Well, the 400s you have ridden must not have had the throttle adjusted, it's been shown many, times on many different dyno's. The XR400 puts about 32hp to the rear wheels, the 400EX about 27.

Drag races I have done seem to support those numbers as well, the runs I have done are all very consistant. My 350X will run away from a 300EX, my 400EX will run away from my 350X, my 250R (with mods) will run away from my 400EX, my Friends XR400 will outrun my 400EX. My RM250 smokes them all ..

It takes a he11 of a lot more than a 330 kit and an 11:1 piston to double the HP of your 300EX engine, heck those are pretty mild mods, they should be extremely reliable and run on premium pump gas nicely. If it were that easy (to double the hp of an engine), everyone and their dog would have 600hp streetable small block Chevy's in their cars, ATV racers would have 65-70 HP 250Rs and 55-65 HP 400EXs, etc..... The fact is, doubling the HP of any engine is no easy task, making it reliable is almost out of the question.

32hp out of a 300EX would make it as fast as a top condition stock or mildly modded 250R, I have never seen a 300EX that even comes close to that task.

BTW, a 350X will not bore to 450cc, it will take a stroker kit and sleeving job to accomplish that. The 350X will bore to 359cc without sleeving.

 

86atc250r...You have once again found a way to pick apart everything i've said. I was maybe exagerating a little when I said "it's fairly easy to double the 300ex's stock hp", if I would have known that I was having every word that I typed scrutinized, I would have said "the 300ex comes from the factory in a VERY mild state of tune". I wasn't bragging about mine being a 330cc(actually it's 352cc's), I was referring to someones earlier question about having trouble with the starter when running a high compression piston.
A 350x motor can be bored and sleeved(dah!) to 452cc's, without stroking it.
We all argue about how fast these 300ex's and 400ex's are, but in reality, neither the 300ex, or 400ex are very fast at all. Go ride an R1 around a race track for a while, now that is fast! To me, just having enough power to have some fun is the goal.

 

You yourself just stated that your information was possibly exaggerated, what do you expect??? I generally take a lot of care to make sure that my posts are accurate, if you want to challenge some of the info I have researched and posted, expect your post to be scrutinized, and if it's inaccurate, expect that I'll correct you. If you find an error in something I post, feel free to correct me, I love learning from folks more experienced & knowledgeable than myself.

As far as boring a 350X to 452, it would take a 92mm piston to accomplish such a task, that's 1.1cm larger than stock. Not only would that be extremely costly, it would not be very smart for many reasons. Heck, I guess if a person had enough money and not enough brains, it could be bored to a full liter....

As for the R1 and 300EX vs 400EX power. That's exactly the point I am trying to make. The R1 is really off topic, and can't be compared... But there is a very real power difference between the 300 and 400EXs. My point is, the 300EX is a great bike for lots of different people, I wish Honda would come out with something between the TRX90 and the 300EX. But what I don't understand is, why folks buy a new 300EX and right away start modifying the engine. If you wanted more power, why not buy the (superior in many more ways than just power) 400EX? I guess you can always make reverse argument, but you won't get very far with me on that one, in 20 years of riding the trails I can honestly say that reverse is not that important to me, much more important is not being bored with your bike, you get hurt when you get bored and are more agressive than the bike will allow.

I would compare the 300EX to my old 200X 3-wheeler, a good beginners bike, but when you get good enough to want/need more, you need to buy a more capable machine, not sink tons of money into mods that will end up costing you more than the difference of the bigger machine.

 

The 250x motor that I run in my RX conversion has served me very well,It has had alot of work done by TC-racing, the crank has been stroked to where it is somewhere around 330cc or so, the timeing gear is sloted and advanced, white bros. cam, high rev valve springs,custom sparks pipe with supertrapp, I have been running this motor a good 3 years or so with no out of the ordinarry maintence, I run premium gas with octane booster, I belive the compression is somewhere are 12:1, its stock bore, I run a 34mm lectron carb, this was a bear to start at first (untill I got the hang of it) since all of the compression release system is removed, you have to stand on the kick started untill the compression bleeds and kick, I dont have to choke and it always cranks on the first kick ( this was acheived by good back pressure and jetting) if you catch it in the right part of the stroke you can kick it without haveing to let the compression bleed, I run "Royal Purple" to keep the temps down I highly recomend this oil, therfore I run no oil cooler.
SwiNdleR

 

Gabe,

How many people really race "stock" quads? Maybe a few beginners, but not anyone that wants too compete. When machines get "modded out", they all become the same type of beast and it is more the "rider skill" than machine.
You don't see how anyone would want a 300EX, when a 400EX is advailable. Here are some reasons(opinions) why I choose a 300EX.
1. I like too have something different. When I go too any track, trail or race. All that I see are 400EX's. Which is good, because they are a great quad. But I like too be alittle bit original.
2. I don't like the looks of either the 300 or 400 in stock form. And I(my opinion) like the looks of the 300EX more when you loose the handlebar shroud and some of the useless other plastic.
3. TC Racing 405cc kit for the 300EX produces 52rwHP. There are very few 400's that can say that. I am considering going 350 or bigger this next winter.
4. The bike fits me. I race in the same class(District 23, QuadSport)as 250r's, 400EX's, Banshee's, DS650's, etc. And I am competitive.
I finish top 10 with these bikes in a field of 80. Not bad......
5. Bigger isen't always better.....Stick with what works for you.

The 300EX is a great bike for me. But does that make it right for you? NO.
These are just my opinions.

Chris 00' TC Racing 300EX

 

Chris, I did not say that I could not see why anyone would want a 300EX. They are nice, beginner/intermediate level bikes. I even said that I would even like to see a smaller unit, around 200cc for more of a beginner, sorta like the old 200sx.

What I don't understand is why someone would go out and buy one, then immediately start considering fairly major engine mods. That may have been a viable choice a couple years ago, but doesn't make much sense today.

You also don't need to race to appreciate the difference between the 400 and 300. Personally I could never be happy with a 300EX, it was never a consideration for me, in fact, the 400EX was barely enough, if it had not been for the excellent handling, the 400EX would not have even been a consideration, I would have stuck with my very capable but old 3-wheelers. My 400EX will probably be for sale as soon as something with more power and equal or better handling comes out. I just can't even see sinking much money into my 400EX with all the choices that will be available soon.

We have been getting a bit off topic lately, my original statement was that the person that asked this question is coming off a Scrambler. I personally think he would be disappointed with the size and power of a 300EX. Why tell him to buy a 300EX and modify the heck out of it??? It just doesn't make sense with the 400EX available.

As far as the TC racing engine making 52 RWHP, I find that really, really hard to believe. That's 3 1/4 times more power than stock, more HP than a Volkswagen 1600, about the same as a CR500. Raced out 400EXs make about 45 real world RWHP as do raced out 250Rs, nicely modified ones make 36-40 reliably. I'm sure the 400EX head is will far outflow a 300EX casting not to mention the zillion other factors that go into it. I would also be very concerned about cooling, crankshaft and rod integrity, engine castings, and transmissions at that HP level, esp from an engine that wasn't designed with performance in mind. Although I must admit, I am not familiar with the details of this kit. Does it include a turbo or supercharger?

Did you get your Axis shocks installed? If so, how you liking them so far?

BTW, is anyone else having trouble with posting on this thread? My last post took 2 tries and it still got semi-hosed up (missing text) as did this one...

(note...
I was referencing the wrong post about the guy with the Scrambler, oops, this one is the guy with the 300EX wanting to modify it with a 350X engine. My comments still pertain to this thread though, with the cost of a 350X engine, then the cost of modifying the chassis to accept it. Unless of course, a person could obtain a 350X engine for a very good price)

 

Different toys...for different Boys......

The TC 405 kit is for real. There are several machines for sale right now in the classified part of the ATVconnection. They all state 52rwHP. With what kind of reliability? I'm not sure....
I know that it is bored and stroked with a different head design. But not sure of all the details.

I have some questions about the adjustability of the shocks, but I will e-mail you separately before we get into that conversation. So far.....so good!

Chris 00' TC Racing 300EX


Gabe,
I am also going too be posting pics of my 300EX on my webpage sometime over the weekend. She is a sharpe looking quad that performs.....

 

I didn't post this to start a fight. I just need more power. And i don't want to lose reverse. Many don't need it. but i do. It's just a must for me.

Well, now i'm thinking just about selling the 300EX and getting a Scrambler 500 4x4, and just forget about Honda, the only ATV i could count on was my Trailblazer!