Building BIG new custom exhaust

[gasguzzler]

I asked a while back and it seems as if no one had tried building an exhaust bigger than what is currently on the market (1.25" primaries, 1.75 after merge to muffler unless it bells out to muffler). So I decided to fab up my own using 1.5" primaries to 2" back to muffler (which is a slip-on Motoworks from KFX that is slightly modified). I don't have a welder or welding skills, so I just cut and taped together today. The custom flanges to mount the 1.5" od pipe to the head were probably the toughest part to source in stainless as the factory flanges don't have enough meat on them.

This is going on a highly modded 416 with the Web 463/9i cam to turn high rpm. The quad pictured was just an extra I've got for mock-up.

I'll try to get more pics when the project is done and I can let you know how it worked.

http://i604.photobucket.com/albums/tt126/kbsupercharged/Customexhaustprojectpic1.jpg

http://i604.photobucket.com/albums/tt126/kbsupercharged/Customexhaustprojectpic2.jpg

[Thumpin440ex]

I am interested to see if this will make more HP then a good aftermarket header set up. Not to piss in the corn flakes but bigger is not always better, back pressure and exhaust velocity play the biggest role on over all power. Def keep us posted. So far it looks nice, wish ya the best of luck. :D


John

[Dubs_Tech]

Looking good! Keep us updated on its progress!

[JOHNDOE83]

Nice!!!!

Looks really good man, Ive been rying to get a exhaust place around here to build one for me but they keep saying they dont sell motorcycle parts:ermm:

I try to say "No, I want a custom built one" they still say they dont sell motorcycle parts....Im like wtf???:rolleyes:

I would have Deffinetly bought one from you and still might if your interested?

[bcleveland]

I see how this could be great or really bad. The bigger the tube the more top end and the less bottom you will have, up to a certain point then you will just kill it all across the board. With that said you will either pick up your top or you killed it. Thats a really big jump in pipe size and is as big as alot of car headers. It looks good and deffinately want your results when done. But in the mean time think about this you said nobody makes a pipe this big. There prob is a reason. Its like saying nobody makes a 6 inch piston for a 400 reason is it wont fit wont work.

[gasguzzler]

I understand the concern over killing torque and being too big. I'm currently running an HMF Competition Series and will do comparisons to that when it's done. I spoke with an engineer at HMF and he believed it would work with my combination. I've already got a cam and extreme head work which have pushed the powerband up significantly, so I've already done some sacrificing on the bottom end in other areas. This combo is ripping in the 7000-9500 rpm range now and I think this will help push it strong up into the 10,000 rpm range. It's an experiment and I'm looking forward to the results or finding out the limitations of the 400ex engine in rpm/power.

I've got 3 400ex's, one of each bore basically, 1 -416, 426, and 440. So I should be able to experiment with it on different sized engines too, although my 416 is the most radical combination/quad.

Thanks for the feedback!

- Brian

[Dubs_Tech]

Good job man i look forward to your findings.

[jman7290]

Looks to be a pita to adjust your clutch cable, other than that looks great!

[jcs003]

I didnt know the 400ex revved to the forementioned range. If you can get it to rev that high with engine mods the ignition system would need some changes. i.e. the rev limiter

[gasguzzler]

I've got a programmable dynatek, so I've currently got the rev limiter set at 10,000 and can raise it if need be.

[gasguzzler]

http://i604.photobucket.com/albums/tt126/kbsupercharged/Bigcustomexhausttackedupside.jpg

http://i604.photobucket.com/albums/tt126/kbsupercharged/bigcustomexhausttacked2.jpg

http://i604.photobucket.com/albums/tt126/kbsupercharged/bigcustomexhaust3.jpg

Got it tacked up, should be done soon!

[Dubs_Tech]

Nice! Definitely get some sound clips up soon!

[chronicsmoke]

Very cool,

Subb'd for results :devil:

[russellsroost31]

that looks like it would be great on a 440 kit or bigger or very high compression

[dxcody]

With an extreme port and polish, valve job and a 12:1 or higher 89mm piston... That thing would be BOSS!

[ben300]

is this gonna be on a tt/flat/circle track set up? we see the slicks on the bike in teh picture, adn i know its just for mock up, but reving that high, with hi comp and some serious valve/head work being done...that thing would SCREAM coming down the straights at a circle track

[gasguzzler]

Yes, this is a flat track/tt/non-studded ice racing set-up. The system will likely not go on the quad in the picture, it was just used for mock-up. It will be a screamer, biggest concern right now is the 39mm FCR not flowing enough, planning on a 44-46mm throttle body with fuel injection next spring.

[bcleveland]

If your gonna be flat tracking then I can give you some advice. If your gonna be running a wide open track with very little backing out the bigger carb might be your best bet and would be worth trying. If its a smaller fish bowl type track that you have to slow way down in the corners and lug the motor then go with a smaller carb. The smaller carb will give you higher port velocity so when the shutter in the carb close it loads up an extra gulp of fuel and when you snap the throttle back open you have a super dense fuel charge that is moving extremely fast to help get that engine turning again. If the carbs to big charge isnt as dense and air moves slow and bike will feel lazy coming off the corner. Also you might want to see about finding you a heavier flywheel in the corners momentum will always be your friend. Also how big of a engine build are you thinking of going with?

[russellsroost31]

hey when you get this done you should make a video of it running so we can hear how it sounds

[gasguzzler]

Got it done and installed on my good quad tonight after spending most of the day tracking down a no spark issue (ended up being stator/crank pickup). I got it fired up a little after midnight, so I didn't take it out for a spin. My initial observation is that it really doesn't seem any louder than the HMF Comp. series system I took off, just a little throatier. As long as it flows good, and I think it will, I'm happy with that. Here are some more pics.

http://i604.photobucket.com/albums/tt126/kbsupercharged/sideshot.jpg

http://i604.photobucket.com/albums/tt126/kbsupercharged/backshot.jpg

http://i604.photobucket.com/albums/tt126/kbsupercharged/topshot.jpg

http://i604.photobucket.com/albums/tt126/kbsupercharged/exhaustcomparison.jpg

[Stickman400]

Damn, that looks legit. Good work, deff. post a vid up when you can so we can hear it anyway.