Will a 300ex motor fit in a 400ex?

[riley1374]

Will a 300ex motor fit in a 400ex chassis? I have a strong running motor and would love to throw it in a 400ex rolling chassis if it wouldnt be that hard. I have been looking for a 250r rolling chassis but they are few and far between. Thanks

[wilkin250r]

You realize that you are going to get dozen replies like "dude just get a 400 engine its way better n faster". It's going to happen, just expect it.

But let's start off there anyways. Is there a reason you want to use this 300EX engine? Is it highly modified? Or maybe you want to race in a 300cc class?

I will say that finding a 400EX rolling chassis isn't going to be as easy as you think. And if you did find one, I just can't fathom the idea of going through the complexity and expense of the conversion, just to put a weaker motor in.

So let's get the simple questions out of the way. Is there a reason you don't want to go the easy route and find a 300EX chassis? And/or, is there a reason you want to use this engine in a conversion, rather than simply getting a proper 400EX engine?

[riley1374]

I am looking to keep the 300 motor because it is already worked and runs like a champ. It will destroy all stock 400ex's, but i have outgrown the 300ex chassis. Thanks

[wes350x]

Originally posted by wilkin250r
You realize that you are going to get dozen replies like "dude just get a 400 engine its way better n faster". It's going to happen, just expect it.

But let's start off there anyways. Is there a reason you want to use this 300EX engine? Is it highly modified? Or maybe you want to race in a 300cc class?

I will say that finding a 400EX rolling chassis isn't going to be as easy as you think. And if you did find one, I just can't fathom the idea of going through the complexity and expense of the conversion, just to put a weaker motor in.

So let's get the simple questions out of the way. Is there a reason you don't want to go the easy route and find a 300EX chassis? And/or, is there a reason you want to use this engine in a conversion, rather than simply getting a proper 400EX engine?

You said my thoughts in your first line.........My bone stock 400ex (when I had it) would kill any 300ex..but good luck with the swap.

[fmftrx300ex]

good luck, i dont know if u had nos on ur 400 but i know i could easily keep up to a bone stock 400ex

[kukerdan]

go for it dude

it should smoke a regular
400ex if its as good
of a motor as you say it is


PS

[trx400EXtreme]

Originally posted by riley1374
I am looking to keep the 300 motor because it is already worked and runs like a champ. It will destroy all stock 400ex's, but i have outgrown the 300ex chassis. Thanks all it takes i a few mods on the 400, and its faster. but answering your question. anything is possible if you want to do all the cutting and fabricating. in the end, it would probably be cheaper to get a 400. JMO.

[TheBlasterMan]

theres no replacement for displacement.

why bother with the headache of engine transfers?

if you gona do an engine swap, put a street bike engine in that!

[sportraxkid]

Id have to agree a 400ex is gutless alone, why would you want to put in a even weaker motor? Even my old 440 with 12.1 comp, ported head, 450 carb, exhaust, hotcam etc etc. would barely beat piped 450's. If you want to do a swap id sell the 300ex and buy a CR500 motor or crf450 and put on the 400ex.