how hard is it to put a 350x motor on a 300ex frame?

[yamahabrendon]

do they bolt up the same or what you have to do to make it work? i am in the processe of puting 400ex on my 300ex and i was wanting more power is this the way to go with a 350ex or is there another motor that bolts up easyer ?

[2muchquad]

you have to gring a half inch or so from the rear top motor mount on the 350,also need to extend the exhaust header a lil'bit to clear the frame.the 350x is the easiet motor to bolt into a 300ex frame by far.almost a dropin.this is for a 350x motor ,400ex motor is different

[rooster300ex]

powroll makes a conversion kit. not cutting of anything at all.

[2muchquad]

you dont need to pay BIG BUCKS for the powroll kit,they want $350 for just the header!ouch.its rally easy with out the kit,dont waste your money

[YZ400EX]

Originally posted by rooster300ex
powroll makes a conversion kit. not cutting of anything at all.

All the Powroll mounting kit is, are some aluminum spacers..There are 3 of them..1 long, 1 short, and 1 medium..(You can be cheap and use washers if you really needed to though)... You still have to cut the upper rear mount though.. there is no way around this..You will also need to have a 350x header modified to clear the frame rail or go with the Powroll exhaust..You will also need a 350X cdi and swap around 2 wires that are in that part of the harness..You will also want to use either a 300ex or 250X carb because it perfoms better in the 350X motor then the 350X carb does..the 250X or 300ex carb is larger than the 350x intake tube so you will need to heat the 350x intake tube up and then put the carb on. it will stretch after awhile of having the carb on it that you wont need to heat it next time..You will also have to have the countershaft sprocket flipped backwards so the sprockets line up perfectly. The rest is all just bolt it up and go.. pretty sure I didnt miss anything..

[wilkin250r]

Just to reiterate, because sometimes people don't believe it if only one person says it. The 350X engine is by far the easiest to put into the 300EX frame. No welding of the frame, not cutting of the frame, just a bit of grinding on one motor mount ont the engine, and thats it. If you ever needed, you could easily swap the original 300EX engine back in.

[notfastenuf4me]

id go with what yz400ex said hes been workin with me on the same conversion he has givin me lots of info on it he can prolly answer all of ur ? the biggestthing for my conversion was finding a header already modified one other thing to look out for is mouting the oil cooler for the 350x motor

[bradley300]

i think you can use a 400ex header, it just needs to be bent just a little

[2muchquad]

you could use the 400ex header,it just need to have the headpipes cut and extended 2in to clear the frame onthe 250/300ex.

[notfastenuf4me]

the only diff between the 2 headpipes is the 350x headpipe need about 3 to 3 andhalf added and the 400 needs 2 so no matter what u gotta modify a head pipe