Modified 2 stroke engine expansion chamber.

[BillyGoat]

http://i150.photobucket.com/albums/s100/HondaATC/500R%20Flat%20Tracker/Pipe%20almost%20done%203-12-08/P1010040.jpg
http://i150.photobucket.com/albums/s100/HondaATC/500R%20Flat%20Tracker/Pipe%20almost%20done%203-12-08/P1010027.jpg
http://i150.photobucket.com/albums/s100/HondaATC/500R%20Flat%20Tracker/Pipe%20almost%20done%203-12-08/P1010024.jpg
http://i150.photobucket.com/albums/s100/HondaATC/500R%20Flat%20Tracker/Pipe%20almost%20done%203-12-08/P1010026.jpg
http://i150.photobucket.com/albums/s100/HondaATC/500R%20Flat%20Tracker/Pipe%20almost%20done%203-12-08/P1010029.jpg
http://i150.photobucket.com/albums/s100/HondaATC/500R%20Flat%20Tracker/Pipe%20almost%20done%203-12-08/P1010012.jpg



I had a lot of fun actually building this. And I only goofed up real bad on about 3 sections in the middle, its easy to tell which ones, everywhere else the bends/cuts/contours actually flow relatively well, theres no real sharp edges or corners except for that screwed up part. I'm sure the next one will be much better, I learned a lot on what to and what not to do on this one. The machine use to be a 1985 Honda ATC250R, and the engine has been replaced with an 85 CR500 engine. Only about 7lbs heavier and another 20hp roughly straight out of the box without any port work or anything. I've got a lot more pics of the chassis work including the bottom frame rail replacements that I might post up later on this evening if anyones interesting. All work done with an oldschool Miller Dialarc HF.

[zapster]

What Fun!!

What does the inside look like??

...zap!

[BillyGoat]

A little burn through, not to bad. If you look close its easy to tell where it did, and didn't. The main screw up was those few center sections (3) made some big gaps that I had to fill (and still have a few left, you can see the one hole). I'm not really use to working with sheet metal and stuff this thin so there was a big of a learning curve.

[Rojodiablo]

Billygoat, I used to roadrace, and we had several Honda RS 250's. When my mechanic would modify a pipe, he would fit and weld a section, then grind the inner weld clean and smooth polish it. Then, he would add the next section. It took a lot of work, because he would tack the pipe together with all the sections, then carefully tag all the sections, and their direction. Using the tacks as markers, he would cut the tacks off, and reassemble the chambers section by section. By smoothing out the inner surfaces so well, we got a TON more scavenging, and in turn, better cylinder filling on the intake side. I love the old ATC's, wish I still had one to play with!!

[BillyGoat]

Hey Rojodiablo, that is pretty cool you had some RS250s! You can probably tell by the way my R is setup, I short track race with it mainly and hit up a larger 1/3mile oval occasionally that is down south of Tampa, FL. The newer 450 quads were giving me a bit of a hard time with my small 270cc motor, I'm a die hard three-wheeler guy (theres something about the instant death infamy they have that I like :)) so the motor up grade was what I shot for. This is the first pipe I've ever had to section, but I've read up a whole lot on exhaust pipes and their designs, I'm pretty familiar with it. I've got the first race of the season March 29th and I've still got to get this thing dialed in but I would definitely like to try my hand at a nother one soon, the base pipe I started with is very cheap at about $100 brand new so not a big loss as if it was a custom made one that had a several hundred dollar price tag. Thanks for the tip on grinding them smooth section by section from the inside, I'll definitely do that next time around.

Do you have any pics of your bikes or anything?

[gourdhedd]

Yes, yes, more pictures! I've got an '83 250R sitting in my shop, mostly in boxes, and a 200X that I still ride a few times a year. And an '85 Honda Odyssey. I love these things, too.

Gary

[BillyGoat]

Man I can't believe all the trike guys here :laugh: I actually have a whole message board dedicated to three-wheelers, its www.3wheelerworldforums.com some of the old school pro racers like Brett Driscoll, Mike Coe, and even the 3Wheeling magazine writer Dean Kirsten (Also of Hot VWs fame) drops by occasionally.



http://i150.photobucket.com/albums/s100/HondaATC/September2007091-1.jpg
Heres a pic of me on the same machine last season with the 270 motor in before it was torn down. Edging out a 450 quad and held him off for a few more laps until I blew through the blue groove in that same corner and he got me on the inside.

Heres a few more misc. ones from last season:

http://i150.photobucket.com/albums/s100/HondaATC/cornersmall.jpg
http://i150.photobucket.com/albums/s100/HondaATC/Scan1Huge.jpg
http://i150.photobucket.com/albums/s100/HondaATC/DSCF4003.jpg