My YZ450 with homemade exhaust

8 replies to this topic
  • johnnydeetz

Posted April 01, 2009 - 02:36 PM


Thought you lads might like to see my latest modification.
My bike is a YZ450, with a WR 5 speed motor, home tuned, its pretty quick now just a little slower than a 650 'Berg, and quicker than most 450's.

My Akro pipe I had before was loud, kept blowing apart, needed re-packing..after numerous and loads of attempts to make it quiet, with success but didnt stay together, I decided to make my own pipe.

As its supermoto I want more top end, so based on the fact that the 748's have 55mm headers, and when I raced a KTM550 supermono I built a 60mm pipe (two 38mm headers into a 60) this was the only way forward.

Step forward my sponsor in road racing, and they made a selection of bends from 50mm stainless pipe, 0.8mm wall thickness with a 38mm to 50mm taper for the stub. I spent 8 hours hacksawing, tacking up, pondering, welding and viola, a new system for no cost !
Coupled with a straight through all titanium oval silncer, and a baffle in the end and its at 97db where the Akro was at 102db - yikes. Th esilencer is longer, bu I made it so it fits behind the number board neatly, and it doesnt stick out any farther than it used to, clears the tyre as well !
Mission accomplished !
Strangely, I gained 1hp throughout the rev range all over not just top end, but is a lot quieter.

At the track, it feels smoother bottom end and just keeps pulling, not like before when it pulled from bottom and went a little weak on top. The dyno graph didnt read what it feels like on track - strange.

Got my first top 10 in the Nationals last weekend, at a track I didnt like. This is only my second season, and 8th supermoto race meeting, so am well made up !

Posted Image

  • ThumperKid250F

Posted April 01, 2009 - 02:44 PM


wow very nice, good clean job you did there:thumbsup:

also good work on getting your first top 10:thumbsup: :thumbsup:

  • FiremanKay

Posted April 01, 2009 - 04:14 PM


very cool, I think AMA needs to bring it down to 96dbs this way everyone will have to have quieter bikes to ride and race.

  • finthat

Posted April 01, 2009 - 04:38 PM


Good job looks sweet....I miss the days when I worked at a welding shop and ran a mandrel bender. Built headers and exhaust for my 4x4. Now I am into bikes and would love to have that machine back.

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  • buzzgrizz

Posted April 01, 2009 - 08:24 PM


great work:thumbsup:

  • johnnydeetz

Posted April 02, 2009 - 02:12 PM


Thanks lads ! :thumbsup:

Finthat, yes it does help when you have the equipment much like you did I ideal job would be doing stuff like this all day, everyday...instead of being a development engineer for boilers !!
Does have its perks though, so I cant complain.

  • rdrata

Posted April 02, 2009 - 04:24 PM


"Deetz Boiler Makers" - Kinda catchy name for an exhaust system? Dominate the race events, and have the big boys buy your brand name out for the BIG BUCK$:thumbsup:

  • gbalias

Posted April 02, 2009 - 05:11 PM


I spent 8 hours hacksawing, tacking up, pondering, welding and viola, a new system for no cost !


whats wrong with that statement! ahhaah...jk

awesome pipe.

good to see a fellow sumo racer on here! cheers!

ive got a 426 for SM racing.


  • MuDPoUNdeR

Posted April 02, 2009 - 09:18 PM


Cool pipe but have you seen the Pro Circuit pipe? (I know it costs money, the big difference in what you did.) Only 94db


Features Include:

* Strictly for closed course competiton!
* Non Spark Arrested system
* Welded Titanium End Cap (same as Team Pro Circuit)
* Meets AMA sound requirements of 94db.
* 3 Piece system which inlcludes silencer, mid pipe and head pipe.
* New stronger Billet Aluminum Mounting bracket.
* Used by Team Pro Circuit as well as Factory Kawasaki and Factory Suzuki.

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