Here's a question for all of the 350X experts. Will a 400EX header fit a 350X?
Just curious at the moment but will influence a decision I will have to make.
First Time Rider
Arm chair racerNew to the board
Here's a question for all of the 350X experts. Will a 400EX header fit a 350X?
Just curious at the moment but will influence a decision I will have to make.
There is no replacement for displacement!!!!!!!!
ATC/ATVs owned:
85 250SX (rebuilding)
At The Back Of The Pack
Arm chair racerFirst time rider
From what I've read you can make it work but it's not a bolt on by any means.
At The Back Of The Pack
Arm chair racerFirst time rider
I asked this same question on here awhile back cuz i want to run a sparks 400ex big core on my 350x. I was told it would work with some mods but noone went into details or posted pics. So I currently have my bike tore down to just a frame and motor. I bought a stock 400ex pipe off ebay and will do some test fitting before i take the motor off the frame for a rebuild.
Coal Shed Racing
Beasley's ATV Services
DEAF MAN CHASSIS
EKO Engineering
2 of the fastest 300ft raptors in the country..
847cc 100hp+
720cc 75hp+ (play bike)
1986 200x, 1986 350x, 1984 110
Power User
Got the holeshot
I did it on my last 350
Fairly easy to do with a welder and sawzemall
You need to lop off the two ends at the head and swap the two clamps that bolt to the head, the 400 ones will not work.
From what i can recall in my very hazy memory, the header needed to be shortened and a small pie cut into it like 3 inches from the end of the head pipe and them bent to get it to line up to the 400 muffler.
Also had to lop off the front stock muffler mount on the frame to get clearance.
Not something alot of ppl will be comfortable doing. Guess it depends onfabbin skills.
Gotta say though, was quiet as mouse with the stock 400ex setup
At The Back Of The Pack
Arm chair racerFirst time rider
Great info! Not looking to be quiet tho! Looking for the preformance gains in the bigger header and just better all around system the the only aftermarket system (DG) thats currently offered. Going to take some guts to gut up a brand new curtis sparks exhaust tho!
Coal Shed Racing
Beasley's ATV Services
DEAF MAN CHASSIS
EKO Engineering
2 of the fastest 300ft raptors in the country..
847cc 100hp+
720cc 75hp+ (play bike)
1986 200x, 1986 350x, 1984 110
Roostin' Away
Arm chair racerRoostin Away
Let us know how it turns out. wouldnt mind a 400ex header myself.
BTW - Did you ever work out the 350x big bore with the XR500 cylinder you had mentioned before?
First Time Rider
Arm chair racerNew to the board
A little modifying huh? Shouldn't be to bad then. I'm already modifying the hell out of everything else. What about a big bore 350X?
There is no replacement for displacement!!!!!!!!
ATC/ATVs owned:
85 250SX (rebuilding)
New to the board
Arm chair racerNew to the board
I got a 400ex aftermarket oversized head pipe cheap from ebay because someone had cut the very end off at an angle. That did not present a problem, because the bend before it was wrong. The bend caused the end of the pipe to be pointed the wong direction to be routed above the trans, inboard of the frame tube. I cut the pipe before the bend, rotated it then welded it back together and it fit perfictly. I must add that I also fabricated the rest of the exhaust from there back, so I can not speak of the potential fitment to any existing mufflers. I modified a supertrapp silencer to connect to the modified head pipe. Sorry, I do not even know the brand of head pipe. I bought it because it was cheap, until I had it I was not sure it would be worth the trouble to make it fit. I had read else where that the primary tubes had to be cut off to swap the flanges that go on the studs in the head because they were different from the 350X to the 400EX, thankfully I found that was not the case. I was told that the 350X head would not accept the 400EX pipe because the head's studs were directy across the port from one another on the 350X, they are not. The 400EX pipe fits to the head with no mods, the back of the head pipe does need to be modified to connect to the rest of the exhaust, at least thats how it worked on mine. I can post picks if any one is interested in seeing how it turned out.
Last edited by 390x; 01-05-2011 at 12:25 AM. Reason: spelling error
At The Back Of The Pack
Arm chair racerAt the back of the pack
pictures plz!!
Power User
Catch me if you can
2 guys now saying the flanges have to be swapped. We went through this last week.
NOS_350X says otherwise. I get real sick of this crap...
Does it FIT or NOT and WHAT has to be changed... I respect Jeff plenty, if he says the flanges do not work, I believe him 100%!!
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country
Power User
4 Wheels? Huh?
Spend $50 and buy a NEW cobra header, then use whatever silencer you want.
80s......185 atc, Yamaha tri-moto 200, 85 200x with tons of work
90s......89 Suzuki quad racer 250 (raced 250 A class for 6 years, late 90s.. custom framed 250x with long travel shocks and a built 350x motor.... built Honda 110
00s...... chomeoly framed 350 RX with all the goodies (thanks to my bro)
2012.....Replaced the 350x motor for a 444cc YZ426
WWW.HREATV.COM
New to the board
Arm chair racerNew to the board
Believe what you want, I did it, a couple posts up I said how I did it. Pictures were requested and pictures are supplied. Feel free to ask questions. I do not claim to know everything about 350Xs, many people here know more than. I know very little about 400EXs. Pics of the header off of the trike are before I modified it. All cuts/welds are behind the point where it is painted black near the back of the head, note the coating in front of that was not disturbed. Sorry, I do not have any pics durring the construction of the exhaust, I had no idea this was so controversial. Picture quality and lighting are not the best: the trike is in my basement, pics are from my phone.
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