View Single Post
Old 06-14-2013, 03:36 AM
hollywood528's Avatar
hollywood528 hollywood528 is offline
Motorized Bicycle Member
Join Date: Feb 2013
Location: Ramona, CA (San Diego)
Posts: 31
Default My attempt building the "Torque Pipe"

EDIT: made a second pipe a few posts down..

You may have seen it before...

After playing around with the stock exhaust a little (restricting, opening up, header length, etc.), I noticed a lot can be done with the exhaust for performance even with the stock setup. Although you can easily hinder performance doing the wrong thing. For a while, it was just trial and error with what I had.

Finally I decided to give the torque pipe a go. I knew from riding motocross years ago, tuned pipes make a huge difference, and different pipes give different powerbands.
Unfortunately, I didn't have any thin sheet metal, so I had to use tubing. I had a few different sizes that were damn close to the dimensions. I cut them to length, then made cuts along the length of the tubing to bend them into a cone. I know it looks ugly as **** and isn't the ideal way to go about doing this, but it's what I had. The stinger starts around the middle of the belly, with the end welded and a few holes drilled.

Now it's all welded up, I had to figure out where to mount this rather long pipe... and I still had to make a 12" header!!! That's when I saw a picture of someone else with a header like this, curving up. Again, probably not ideal having the bends, I know. The header is a piece of straight pipe cut into several small sections to get the bends. I also cut out a flange to mount to the exhaust port.

Next was time to fit everything to the bike and weld it up. I also added a strap to the middle of the pipe to connect to the frame for support.

I excitedly rolled the bike out and started pedaling to crank it over.
At the very first rev I was impressed. It actually sounded like a motorcycle!! And it was still cold. After it warmed up for a little bit, I started cruising and immediately felt the power gain! Holy Crap!!! It actually set me back in my seat! The torque gain was amazing.
So now I'm cruising along loving the torque, but afraid I just gave up all my top end. Again, amazingly it kept going. I know I still got up to my original top speed (29mph).
Tomorrow I will get the speedo and see if my top speed has actually increased. I honestly think I got a few more MPH, but I'll check for sure tomorrow.

This is an awesome upgrade for all around power, plenty of torque and still has good top end. I love the sound, it's like a real dirt bike, especially when you rev it up and let come back to idle.
The set up now is not too loud. I'd say it's similar to the stock exhaust. And this is without a silencer, just the long stinger.

Now, knowing the gain that can be accomplished, even with my ugly torque pipe, I plan to get the right materials and make another go at it.
Reading through all the information Dragonfly75 has posted on his site and playing with the excel file, I might make a few changes to get a little more mid-range. I don't have to many hills around me so I can afford to let some low end go.
I may go with a smaller sprocket first to see how that works out. I am still running the stock 44 tooth. Before I made this I was thinking a 40 tooth, but with this awesome pipe, perhaps I could use a 36 tooth! I am a big guy, 6ft 220lbs, "I'm not fat... I'm big boned"

Below you can see how it tucks under the frame to prevent burnt legs

Last edited by BarelyAWake; 01-25-2014 at 01:01 AM. Reason: dead links
Reply With Quote