250R motor in 400ex frame, will it work?

[QuicktimeRacing]

Just wondering if anyone has ever put a 250R motor in a 400ex frame. I have an 85 250R 3 wheeler and a 99 400ex frame and was debating about attempting the swap. It looks like the rear swing arm will interchange but I wasn't sure what else would be involved as for items such as the radiator and what not. Anyone have more details on this? -Trent

[Fastyfz]

you might be able to get the motor in with some custom motor brackets but the swingarm will not fit you would be better off finding a 250R frame way better geometry and withe the 450 craze 250R parts are showing up everywhere

[QuicktimeRacing]

What is it that makes the swing arm not fit. I measured the the overall width and the two were the same. Is there more to it?
-Trent

[Joecool1264]

Dirt Wheels did a story a couple of years ago about a guy that ran the same set up. Think he MX'ed with the 250R and XC'ed the 400. I don't remeber the year or issue though. Maybe someone collects the mags?

[curious george]

service honda.com makes a 250R upgrade kit for a 400ex. you should try there.

[400exMO]

Yeah I've seen in a magazine where somebody put a 250r engine in the 400 frame. I can't remember all the modding done but it worked. Give it a shot if you have the resources.h

[400exrider707]

www.servicehonda.com You can buy one right there.

400ex frame with an 01 cr250 motor, almost 50hp to the rear wheels, and you can upgrade it with whatever you like, they have everything from different pipes to supsension and axles and wheels, etc etc. Kinda price though, I think it starts out at around 8000.:eek2:

[curious george]

no the engine and sub frame is only 4500 but still pricey

[Mobile Dyno]

Originally posted by 400exrider707
www.servicehonda.com You can buy one right there.

400ex frame with an 01 cr250 motor, almost 50hp to the rear wheels

It does Not put down 50hp in a quad frame. ;) you will be lucky to see 40hp at the rear wheel and that would be with mods

[Flynbryan19]

Why not just buy a 400ex frame.......? They're everywhere.

[QuicktimeRacing]

I think I may attempt to do the swap. I have a bare 400EX frame and a complete 250R 3 wheeler. I don't care much for the 3 wheeler look or the way they ride. I actually got the 3 wheeler as partial trade for my old 400 but got to keep most of my 400 parts so I don't think it will be to bad. The price of the 400 stuff seems to be signifigantly cheaper than the 250R stuff too. I think that the motor and swingarm from the 250R will go in with very little modding I do however think that the exhaust, wiring and radiator mounting may get a little wierd but thats what a welder is for I guess. Does anyone have pics of any of these 250/400 swaps? I would like to get started soon and would be curious to know a little more about it all...

What kinda performance can I expect from it with a mostly stock 250R motor? Will it be quicker than a generally stock 400?-Trent

[redracer10]

Everything can work on a atv if you got the money!! But i just have one question why not buy a 250R it would probably be alot cheaper and easier because you will have to buy a engine mounting kit anytime you put a new engine in or why not buy a 400EX frame for your 250R?? Just seggestions but the 250R motors wont make a 400EX go anything like a 250R i dont know why people put the bigger engines like that in their 4-wheelers and think it will run like the qaud or whatever the motor came out of... the 250R was a rocket because of its weight and build ur better off buyin a 250R

[400exrider707]

Originally posted by Mobile Dyno
It does Not put down 50hp in a quad frame. ;) you will be lucky to see 40hp at the rear wheel and that would be with mods

I got that directly from yamawheels (dirtwheels). With the FMF I believe it was like 46 and with the pro-circuit pipe it was right at 49ish!? I know every dyno is different but thats just what I was going from.:confused:

[QuicktimeRacing]

Originally posted by redracer10
Everything can work on a atv if you got the money!! But i just have one question why not buy a 250R it would probably be alot cheaper and easier because you will have to buy a engine mounting kit anytime you put a new engine in or why not buy a 400EX frame for your 250R?? Just seggestions but the 250R motors wont make a 400EX go anything like a 250R i dont know why people put the bigger engines like that in their 4-wheelers and think it will run like the qaud or whatever the motor came out of... the 250R was a rocket because of its weight and build ur better off buyin a 250R

Maybe I'm missing something... The reason I was going to make the swap is because I prefer the look and ridability of a quad compared to that of the 250R 3 wheeler I now own. I figure if I can have a quad for fairly cheap out of putting the motor into the 400 frame I have sitting here then it wouldnt be so bad. I realize that a 250R 3whlr is quick because of its weight but the 250R quad can't have a weight much different than that of a 400ex. I also thought that a 250R motor made more power than a 400ex motor, is that not correct? -Trent

[400exMO]

If you can handle the fabbing of the 400 frame use the one you already have. And the 250 motor will be mucher faster than the 400, If you get it running perfect. Definentely do the swap, it'd be fun and you could come out with a great quad. Just make sure to keep us updated!

[underpowered]

Originally posted by QuicktimeRacing
What is it that makes the swing arm not fit. I measured the the overall width and the two were the same. Is there more to it?
-Trent

The swingarm is a direct bolt on. there are a few years that ar the same at teh 400ex, but it is 1.25" longer than a stock 400ex swingy. That is one of the reasons why aftermarket companies do a =1.25" for the 400 since it is just astock 250R swingarm.

[spent21]

Just a note on the 250r quad frame versus the 400ex frame. the stock 250r frame is a square tube frame versus a round tube frame. round tubing is lighter and stronger than square tubing.

also, i don't understand anything redracer10 said earlier about a 250r out handling a 400ex. The 400 was built off of nearly identical frame geometry as the 250. i remember when the 400 came out and dirtwheels was saying this was the best bike since the 250r that honda has put out...blah blah blah

one plus for the old r frame is it has a removable grab bar. the 400 does not, but the 400 does have a subframe that the r does not have. hmmmm
i even think there are a few guys over at the 250r forum that have pulled this one off. i'll try to find it and post a link sometime.

[redracer10]

A 250R motor wont work in a 400EX like it would work in a 250R , the 250R motor is special built for the bike so when you transfer it to a 400EX it wont be as fast as the 250R. Thats just like puttin a crochrocket motor in a banshee the banshee doesent go as fast as the crochrockets original body it was in....

[underpowered]

Originally posted by redracer10
A 250R motor wont work in a 400EX like it would work in a 250R , the 250R motor is special built for the bike so when you transfer it to a 400EX it wont be as fast as the 250R. Thats just like puttin a crochrocket motor in a banshee the banshee doesent go as fast as the crochrockets original body it was in....

and arent all motors specifically built for the frame teh reside in? I dont really see teh point in putting a 250r motor in a very similar chassis, but it is not me doing it. a 250r would be jsut as fast in a 400ex as it was in teh R frame.

A crotch rocket motor will not go as fast in a quad frame as it did in the bike frame because the Quad is no meant to go that fast or have that much power. plus the quad has alot mor wind resistance than the bike does. sure you could gear teh quad the same as teh bike and it would go a comparable speed, but the frame is not ment to handle that type of power.

[QuicktimeRacing]

Originally posted by redracer10
A 250R motor wont work in a 400EX like it would work in a 250R , the 250R motor is special built for the bike so when you transfer it to a 400EX it wont be as fast as the 250R. Thats just like puttin a crochrocket motor in a banshee the banshee doesent go as fast as the crochrockets original body it was in....

I have absoluetly no clue what your talking about... It all comes down to power to weight. Why would a 250R quad be any faster than this setup would be? Do you think that the weight is that different between the two or that the 250R quad is a much more aerodynamic design? What am I missing? :confused:

[QuicktimeRacing]

Originally posted by underpowered
and arent all motors specifically built for the frame teh reside in? I dont really see teh point in putting a 250r motor in a very similar chassis, but it is not me doing it. a 250r would be jsut as fast in a 400ex as it was in teh R frame.

A crotch rocket motor will not go as fast in a quad frame as it did in the bike frame because the Quad is no meant to go that fast or have that much power. plus the quad has alot mor wind resistance than the bike does. sure you could gear teh quad the same as teh bike and it would go a comparable speed, but the frame is not ment to handle that type of power.

Your missing the first posts I made. I think if you go back and read them this will all make more sense to you. It's on a budget somewhat and I can work in some individuality to the mix. I do agree that it would be comparable to the 250R quad if not a little faster given that the frame for the 400 may weigh less. -Trent

[redracer10]

I have absoluetly no clue what your talking about... It all comes down to power to weight. Why would a 250R quad be any faster than this setup would be? Do you think that the weight is that different between the two or that the 250R quad is a much more aerodynamic design? What am I missing?



Well, The 400 doesent have the same body a 250R does which we all know, so the 400 frame won't have the same speed as a 250R a 250R is much lighter when it is all put together then a 400 is if you dont believe me weigh the atvs at a dry weight..And a 250R is built alot more fore racing by aerodynamics in its fenders then the 400EX....As for the post UNDERPOWERED made I dont know what your smokin but if you put a new engine in a bike that bike can handle that engines speed... Nothing is holding the engines speed back but its aerodynamics so when you said..........A crotch rocket motor will not go as fast in a quad frame as it did in the bike frame because the Quad is no meant to go that fast or have that much power....that is cracked up because you put a new engine so now it does have that power... explain what your sayin but i dont understand it if you have a new engine

[underpowered]

Originally posted by redracer10
I have absoluetly no clue what your talking about... It all comes down to power to weight. Why would a 250R quad be any faster than this setup would be? Do you think that the weight is that different between the two or that the 250R quad is a much more aerodynamic design? What am I missing?



Well, The 400 doesent have the same body a 250R does which we all know, so the 400 frame won't have the same speed as a 250R a 250R is much lighter when it is all put together then a 400 is if you dont believe me weigh the atvs at a dry weight..And a 250R is built alot more fore racing by aerodynamics in its fenders then the 400EX....As for the post UNDERPOWERED made I dont know what your smokin but if you put a new engine in a bike that bike can handle that engines speed... Nothing is holding the engines speed back but its aerodynamics so when you said..........A crotch rocket motor will not go as fast in a quad frame as it did in the bike frame because the Quad is no meant to go that fast or have that much power....that is cracked up because you put a new engine so now it does have that power... explain what your sayin but i dont understand it if you have a new engine

I am saying that the Frame of the quad was not designed to handle the power put out by the crotch rocket motor. teh bike the motor came out is easily capable of 150+ miles and hour, 200+ in some cases, but a quad frame and handleing is not made to go over 100, let alone 200. I know because of the engine is has more power, but it cannot handle all the power and use it to its full potential.

And for your whole Body, aerodynamice theory, it will make some difference, but not that much ecspecially if you shave the fenders. Plus the Dry weight of a 400ex stock is more than a 250r dry weight for many reasons :it is a 4 stroke, Has more electrical components, ect.. with a 250r motor, it will be right around the same weight as the origional.

QuicktimeRacing-I understand what you are doing and your logic. Sounds like a good idea if you have the resources.

[redracer10]

I am saying that the Frame of the quad was not designed to handle the power put out by the crotch rocket motor. teh bike the motor came out is easily capable of 150+ miles and hour, 200+ in some cases, but a quad frame and handleing is not made to go over 100, let alone 200. I know because of the engine is has more power, but it cannot handle all the power and use it to its full potential.


I guess u dont understand what I'm sayin now.... The frame of a 4-wheeler does not contol ur speed by the design... The engine controls your speed the more times ur piston pumps the faster your bike.... I think you are talkin bout aerodynamics of a frame which wont slow it down but 5 MPH on a 400EX with a 250R motor....I have 1 thing to see to the original poster who is going to do this to his 400EX......JUST BUY A 250R... its going to be cheaper. trust me I have a 250R and a 440EX and the 250R's are expensive but just sell your 400EX and 3-wheeler 250R and you will have the money... I dont see your point in doing this or bore your 400 to a 500cc stroker and you will smoke 250R

[underpowered]

i understand, it is you that does not. it is more than just power that makes something fast. Like a car, for example. Why does a indy car go so much faster than a Nextel cup car fromteh NASCAR series go so much faster on the same track. The Indy Car does not have more Raw horsepower,but Handles better than the Nascar. Like i said, powe ris not everything if you cant get it to the ground. A quad chassis is not made to take any corner at 100+ mph like a streetbike is. Plus the Live axle on a quad will want to push the front end through the corner, even more so is you are applying throttle.

[spent21]

redracer, i think i'm dumber now for reading that!! you put a lighter engine (250r) (and the 400 engine does weigh more, if you don't believe me check the dryweights) in the 400 frame with more power and it WILL be faster than the 400. you put the 250r engine in a LIGHTER frame than the original 250r frame and it WILL be faster. and what's this more the piston pumps?

why do you think ALL of the aftermarket 250r frames are round tube frames? huh?

the 400 is more aerodynamic than the 250....HAHAHAHAHAHAHA.

i'm not addressing the streetbike issue. apples and oranges.

as for selling both as you suggested, he doesn't have a full 400, he only has the frame and a 250r trike.

to hell with it i'm wasting my breath with you.

[redracer10]

WHOA there SEABUISCUIT!!! when did i say a 400 frame is more aerodynamic then a 250R frame heres what i said....And a 250R is built alot more fore racing by aerodynamics in its fenders then the 400EX ...thats a straight copy and paste of what I said nowhere does it say a 400 frame is more aerodynamic... I think I know about 250R and 400EX I have 1 of each and I have 10,000 in each.... I know alot more about both of this bikes then alot of people on here..

[Tri-valleyracin]

i say go for it cant hurt to try a new thing can it.

[spent21]

i have both too sister boy. and where did i say the FRAME was more aerodynamic? I was just laughing at the statement of either of them being "aerodynamic". they aren't spaceships or racecars. they're ****ing 4wheelers. lets just address this for arguments sake.... you're saying a 250r is more aerodynamic than a 400?? in what way? the smoother edges? lower profile? lack of a lardass on it?

set the crack pipe down and walk away slowly.