new exhaust/mod jetting

[finsteratv]

looks like im picking up a 450r muffler with HRC tip which i will be fabbing up to my 400ex. ive heard of these 06+ mufflers flowing real well with the new tip so im going to try one out. im also removing my choke(thoughts on that) possibly grinding header welds and im also buying an aftermarket foam filter. JETTING THOUGHTS?
i was thinking 155 main 42 pilot and 05+ carbs like mine dont have a needle. thoughts?! thanks guys!

[JOHNDOE83]

sounds like your on the right track but, Why a 450r muffler?

I just saw somewhere a complete new exhaust and intake setup for like $289 that bolts right on.

If your gonna modify your stock setup to adapt a 450r exhaust and you dont like the outcome %100, you will wish you got the right thing instead.

[CJM]

I have an extra header, if you muff it up lol

[finsteratv]

well i mean 30 bucks and other guys have done it too..plus i need it somewhat quiet for trails. guy who did it i bought a sparks key from and said just mock it up to your header then move the rear exhaust mount(re-weld) or make a bracket to fit. figured ehhh why not! im always up for a building challenge haha

[Hult250R]

Ive got an '07 450R muffler on mine.
Youll have to cut the top mount off the 450R muffler and move it forward about 2 inches. The lower mount will line up by drilling a new hole about 3/4" above the existing hole.

Also youll have to have a sleeve made to make the end of your header larger so the 450R muffler will clamp down on it.

Im a machinist and I have a TIG welder in my garage so the fab work was no big deal.
I turned a piece of stainless round stock to an interference fit over the stock header. Cut off and TIG'd the top mount back on the muffler.

Be very careful when welding the mounting bracker back on. The stainless shell of the muffler is VERY thin. Like pop can thickness. Its super easy to burn holes in it.

Good luck man

[finsteratv]

thanks for more info Hult! i might be goin to the scrap yard tommorow night to buy more tubing somaybe i'l try to find somthing that will work. either way im up for a challenge :chinese: