Changing pipe curve?

[Tbrock77]

Does changing the curves in a pipe effect performance? if so, how much? I'm strictly talking changing the curve, not the length.

 

[jus_me]

If you mean cutting the curve like as a slice you need to add that slice to the other side (like making a tighter radius/or less of a radius) .. If just taking a chunk out than it will affect performance yes.. How much all depends on how much you take out and where.. Expansion chamber volumes equates to allot of math. Messing with that math even the littlest bit affects things.

What is it you are looking to do ?




This may help a little bit.
http://www.motorcycle.com/how-to/ho...ambers-work-and-why-you-should-care-3423.html

 

[Tbrock77]

I'm preparing for a yz250 swap. Just trying to get the last bits of info so I'm not walking in blind.

 

[Larry's Shee]

So, somewhat major surgery? Cut and rotate is fine, for a small change. Major bend should use a pie cut. Cut straight halfway on side you want outside of bend, notch (pie cut) other half. This might not work real well as the factory pipe is not straight cones.

Ok, this idea might be a little hard to follow: Make a paper mache` model/mold of the pipe. https://www.google.com/search?site=...7.0....0...1c.1.64.hp..2.6.1141.0.Fb-5Q6ICbrE
Obviously have to split it and may have to cut it to get it off, but it will allow for mistakes till you get it right. I got this idea because I've been thinking of a hybrid, bigger quad and BIG 2smoke.(350+)

Also check out member "Best" he did a hybrid and cut the pipe in two pieces and used flanges.

 

[Tbrock77]

So, somewhat major surgery? Cut and rotate is fine, for a small change. Major bend should use a pie cut. Cut straight halfway on side you want outside of bend, notch (pie cut) other half. This might not work real well as the factory pipe is not straight cones.

Ok, this idea might be a little hard to follow: Make a paper mache` model/mold of the pipe. https://www.google.com/search?site=...7.0....0...1c.1.64.hp..2.6.1141.0.Fb-5Q6ICbrE
Obviously have to split it and may have to cut it to get it off, but it will allow for mistakes till you get it right. I got this idea because I've been thinking of a hybrid, bigger quad and BIG 2smoke.(350+)

Also check out member "Best" he did a hybrid and cut the pipe in two pieces and used flanges.

I might give that a try. I luckily have 3 250 pipes laying around, all that were designed for power valved motors.

I don't have a roller so I can't make my own pipe, that was tossed up in the air because I know a few 2 stroke motor builders that could help me with the pipe design.

 

[Larry's Shee]

"designing" one is easy, building it is the hard part
Custom built pipes get a little pricey.

 

[Tbrock77]

Building one isn't hard when you've got 2 and a half engineers (I'm the half haha) the other 2 working for a tool designing firm and can definitely do it but they don't have a roller.

 

[jus_me]

You don't necessarily need a roller. You can do hydroforming.

http://www.bing.com/videos/search?q...&mid=6AC5521E8110BB87AD036AC5521E8110BB87AD03
There are also 2 stroke expansion chamber programs you can download. Some are free, and some cost $$.. I highly recommend a program if you decide to make your own. Here is a free one along with some reading that should help you out.
http://www.dragonfly75.com/motorbike/ECdesign.html

 

[Tbrock77]

I think I'm just going to modify the stock pipe. I was looking at it and it won't take much to do what I want.