Cutting down the exhaust!

I need some info on cutting down the exhaust on the 450, it would be nice to have it a little shorter! if anyone has done this please post. Does it change the power? and if so bad or good? :cry::cry:

I too would be interested in this very mod.

Anyone done this?

I need some info on cutting down the exhaust on the 450, it would be nice to have it a little shorter! if anyone has done this please post. Does it change the power? and if so bad or good? :cry::cry:

I say bad - as the length of the exhaust has been designed for maximum performance - don't chop it - replace it with a lighter better alternative - most every slip on and full system is shorter - then when you sell your bike, sell with stock exhaust - sell the replacement exhaust separately - :cry:

I've done this. Very Very small difference. Just a bit louder. I only did it because I am getting an aftermarket system this spring. Also, you can pick up a stocker for $40 or less. It definitly looks way better than sticking out.

i did it too. i cut 3" off. then i modified my PMB end cap as well. both made a small difference. but that little difference was free so if you dont have the money to spend on an exhaust system then cut yours.

The difference you are going to see with a shorter muffler will give you more top end charge. A longer muffler works better down low and mid range. You can buy different lenghts from fmf but for 4-strokes longer the muffler more low end performance you will have trust me. I wouldn't do it if I were you.

Just my 2 cents,


I did this on my 2002 YZ426, I used a band saw, and cut 4 inches of the can,then just re-drilled the holes for the endcap.

I decided to do this when I went to the salt lake city supercross and seen a privaters 250F that had about 4in. cut off of his can.

Its really easy to do, makes it alittle louder, alot better looking, and doesnt mess with the power to much.(that I noticed) :cry:

with 3" cut off mine and the modified PMB end cap mine is quite a bit louder. probably 102-105dB. but you most likely wont modify the end cap so it shouldnt be too loud. it makes just a lil difference in noise level by cuttin it.

when I was racing road bikes (at Daytona), we had special exhausts for high speed tracks that had shorter cans. The longer can gave more low and mid. The shorter can gave more top end speed (very helpful at Daytona!). At Daytona you spend more time at full throttle (in top gear) than any other track. I think I counted 21-23 seconds one time on one straight stretch.

Data acquisition on some of the bikes showed rear wheel speeds in excess of 200 mph(207 to be exact), although front wheel speeds were in the area of 193mph, so these were very fast bikes.


don't cut your pipe unless you are willing to give up lowend and midrange. Cut your pipe if you only care about top speed (land speed record YZ or something!). It may be useful for supermoto, but most races are won exiting corners and low and mid power helps this the most.

I ended up cutting 7" off my stock pipe(04 yz450) with a bandsaw. Be careful not to saw through the center pipe(the one that the packing goes around). Then fit the end cap and cut down the center pipe accordingly. Drill the new holes. Use the stock Yamaha rivets. As far as power gains/losses go, you might see the change on the dyno, but riding the bike I didn't notice a change. I cut my pipe down because I can't see paying $400+ on an aftermarket silencer with maybe 1 hp gain.

i wonder if cutting down exhaust would make the bike a little more ridable on the bottom end.i just got my bike and was riding a 250f , and the power differance is big,but i think i will try to get used to it first,i can always cut it later but you cant add mor on afterwards.

7 inches! Are you serious? That seems like a lot man.

Serious as a heart attack. My silencer measures 9 1/4", not including the end cap. Now from the side all that is visible is the end cap. Originally, I had cut 6" off and used some cherry max aluminum aircraft rivets. The heads popped off a few because of the vibration and the others worked themselves loose, resulting in holes that were blown out. So, I took off another inch and installed the stock rivets with no problems.

I cut 3 inches off my 2002 426 muffler and IMO the bike runs better/sounds better and it def looks better. It's for sale if anyone is interested. It comes with a extra brand new muffler packing.$60.00usd plus shipping.Oh and it's a Canadian model.

Can One Of You Guys Post A Pic Of The Muffler Cut Down

I Might Do It

The Dang Thing Sticks Out Like 4 Inches Plus And Looks Dumb

Been there and done that. I cut 4" off of mine and noticed quite a bit of differance in the upper RPM range but I also have ported and polished the head.

Wow That Does Look Alot Better

I Guess I Need To Find Someone With A Band Saw

Wow That Does Look Alot Better

I Guess I Need To Find Someone With A Band Saw

Just use a chop saw with a carbide blade :cry:

Cutting your muffler also will raise your loud motorbike, redneck coolness by about 5 points. As well as help piss more people off who are already mad at the noise levels of dirtbikes at both private land and motocross tracks. It is a great thing to do for the sport for extra power that you will probably not even notice that much. Sorry to be the PITA about this...but it is the truth

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