Exhaust Question

Fulltimer · Oct 8, 2011

I have to much time on my hands and the bike is laid up! Bad combination for sure! I know some guys on here have run straight pipes. What are the effects of a straight pipe?

Idea #1
I also have a SBP expansion chamber. I was thinking of running the header tube down under the frame and put the xchamber underneath. Then run a tail pipe to about the rear axle.

Idea #2
This one excites me a little! Bring the header tube down under the frame. Right before the back tire put a "Y" pipe in it and run an exhaust pipe back to the axle on EACH side. Dual straight pipes with a down turn end piece.

Here is what I will be working on:

As it is right now I have saddle bags on it. I have moved that el-cheapo 2 legged kick stand up front and removed the factory kickstand. I also removed the ugly turn signal control!

The one thing I don't want to loose is low end power. That is a must. Give me your thought of wisdom oh mighty members of the powered bicycles!

Terry

Fulltimer · Oct 8, 2011

I just took a measurement. From the exhaust port to the rear axle is 42".

Terry

Fulltimer · Oct 9, 2011

I guess I'll go it alone.

Terry

Venice Motor Bikes · Oct 9, 2011

Expansion pipes are designed to work with the header pipe being a certain length; so using one with a super long header pipe will lower the performance.
If you look at some of stretch bikes I've built, you can get some ideas of what you can do.

The_Aleman · Oct 9, 2011

This needs a bit of clarification. A long header pipe does not "lower the performance", it broadens the usable power band at the expense of peaky high-end output. You prolly meant in the way that you don't get as much top speed, but people that do more than just go flatout might prefer nice torque at low speeds around non motorized bicycle riding civilians or the like.

Serious. Sometimes, having the ability to go 8MPH and retain crisp engine response is handy

Venice Motor Bikes said:
Expansion pipes are designed to work with the header pipe being a certain length; so using one with a super long header pipe will lower the performance.
If you look at some of stretch bikes I've built, you can get some ideas of what you can do.

Fulltimer · Oct 9, 2011

If I were to never go over 20 it wouldn't bother me any. I usually cruise around 10 to 15 anyway. If I were to use the expansion pipe it would be right under the motor. So the header wouldn't really be all that long.

Terry

Venice Motor Bikes · Oct 9, 2011

The_Aleman said:
This needs a bit of clarification. A long header pipe does not "lower the performance", it broadens the usable power band at the expense of peaky high-end output. You prolly meant in the way that you don't get as much top speed, but people that do more than just go flatout might prefer nice torque at low speeds around non motorized bicycle riding civilians or the like.

Serious. Sometimes, having the ability to go 8MPH and retain crisp engine response is handy

Expansion pipes also need a certain amount of header pipe length to give proper low RPM power too!
Most people have come up with a length of around 12" for low end power, & shorter for higher RPM power for HT engines.

If you want to use a super long header pipe, you might as well just use a stock muffler at the end of it, & it'll probably work the same.

Goat Herder · Oct 9, 2011

I concur with Venice. With a long header like that it would prolly be best to simply stick with ecstatics. I mean put something there at which point that compliments the looks of the build.

Fulltimer · Oct 10, 2011

I just took a measurement. From the exhaust port down under the frame is 12". It would almost be a 1/2 circle pipe. So that part would be okay. Then attach the expansion chamber. Now, will the length of the tail pipe have any effect on performance?

Terry

Pablo · Oct 10, 2011

I would say if you can get the chamber within 15-16" it will still have some positive effect. I've seen a couple ~ 20" that still were better than stock. The tailpipe after the chamber will have little effect on performance.

But what a nice looking rig, do what you need to do. You have the knack!

Haha like the large white plastic ties - I use (a bunch of) those to redundantly secure the battery pack on the SBP secret test bike.

Fulltimer · Oct 10, 2011

That was to hold the turn signal switch on. I took it off. It was just to bulky and ugly.

Terry

biknut · Oct 10, 2011

I wouldn't worry to much about how long the header is. This pipe has more than 25" of header and it runs great. The top end power was only slightly improved, but bottom end and mid range are killa.

Search

Exhaust Question

Fulltimer

New Member

Fulltimer

New Member

Fulltimer

New Member

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles

The_Aleman

Active Member

Fulltimer

New Member

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles

Goat Herder

Gutter Rider

Fulltimer

New Member

Pablo

Master Bike Builder & Forum Sponsor

Fulltimer

New Member

biknut

Well-Known Member