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Expansion Chamber
Discussion at Motorized Bicycle Engine Kit Forum in the High Performance Bicycle Engine Tips forum. Could one of you guys tell me the inside diameter ot these tuned pipes.I need to know how big ...  | | 
06-18-2008, 09:57 AM
|  | Motorized Bicycle Builder | | Join Date: May 2008 Location: Decatur Illinois
Posts: 33
| |  Re: Expansion Chamber
Could one of you guys tell me the inside diameter ot these tuned pipes.I need to know how big it is wear the header slides in.I have a friend that has a supplier
that sells pipes with extreme bends for industrial uses plus he is an excelent welder.
Last edited by HOOKWORMRIDER1 : 06-18-2008 at 10:02 AM.
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06-18-2008, 10:04 AM
| | Motorized Bicycle Builder | | Join Date: May 2008 Location: Decatur Illinois
Posts: 33
| | Re: Expansion Chamber
Could one of you guys tell me the inside diameter ot these tuned pipes.I need to know
so i can build my header. |
06-18-2008, 10:11 AM
|  | Master Motorized Bicycle Builder | | Join Date: Mar 2008 Location: Treasure Coast, Florida
Posts: 601
| | Re: Expansion Chamber
The inside diameter of mine was 3/4". I used 3/4" copper and couplings to mate it to the header. |
06-18-2008, 11:35 AM
|  | Moderator | | Join Date: Jan 2008 Location: Pampa, Texas
Posts: 1,382
| | Re: Expansion Chamber
3/4" emt conduit works pretty good to. Plus it bends fairly easily...................
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06-18-2008, 12:26 PM
| | Master Motorized Bicycle Builder | | Join Date: Mar 2008 Location: Treasure Coast, Florida
Posts: 601
| | Re: Expansion Chamber
Quote:
Originally Posted by Ghost0  Well just to clarify, the use of the 3/4 copper fitting that fits over the pipe means that the outside diameter of the pipe is 3/4. So the inside diameter of the pipe is less. Just remember steel and copper tube have their own set of standards and ways of measuring. I am pretty certain that if you find steel tubing that has a 3/4 outside diameter then that is the one you want. The wall thickness of the pipe is around 1/16 of an inch. Hope this helps. | On my installation that is NOT correct. I used 3/4" plumbing copper. Plumbing copper is measured inside diameter. The outside diameter of the copper is 7/8" as is the outside diameter of the chamber, so the INSIDE diameter of the copper COUPLING is 7/8". The copper coupling was a very good fit on the chamber, but a bit loose on the header (original muffler header).
Last edited by misteright1_99 : 06-18-2008 at 12:44 PM.
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06-18-2008, 12:56 PM
|  | Master Bike Builder & Forum Sponsor | | Join Date: Dec 2007 Location: Duvall, WA PNW
Posts: 1,704
| | Re: Expansion Chamber
Quote:
Originally Posted by misteright1_99 On my installation that is NOT correct. I used 3/4" plumbing copper. Plumbing copper is measured inside diameter. The outside diameter of the copper is 7/8" as is the outside diameter of the chamber, so the inside diameter of the copper COUPLING is 7/8". The copper was a very good fit on the chamber, but a bit loose on the header (original muffler header). | Actually I agree - plumbing copper is ID. My copper coupling was a bit loose on the little header, so I tried to expand it a bit (probably didn't make it much larger), then I roughed both piece up, but didn't remove any material - then I used some $2.99 exhaust system sealer gooze (I'll find the brand and such when I get home) to slip them together nice and snug. Seems to be holding well. |
06-18-2008, 10:22 PM
| | Master Bike Builder & Forum Sponsor | | Join Date: Dec 2007 Location: Duvall, WA PNW
Posts: 1,704
| | Re: Expansion Chamber
mr1-99 - It does look like your pipes are slightly different diameter than others.
Anyhow the goo I mentioned is Permatex #80333 tailpipe putty: PERMATEX 80333 MUFFLER & TAILPIPE PUTTY |
06-18-2008, 11:01 PM
| | Master Motorized Bicycle Builder | | Join Date: Mar 2008 Location: Treasure Coast, Florida
Posts: 601
| | Re: Expansion Chamber
Cool Thanks Paul, I have JB Weld on it now, it has held for about 50 miles. If it fails I am going to weld it... It cant fail and fall off as I have a support under the pipe as well as a hanger on the chamber. I will just keep and eye on the header to pipe seal.... |
06-19-2008, 01:32 PM
|  | Master Motorized Bicycle Builder | | Join Date: Mar 2008 Location: Bellingham, WA
Posts: 218
| | Re: Expansion Chamber
Sorry for the misleading, and now deleted, incorrect information. I was going from memory and well, apparently my memory isn't very good. |
06-21-2008, 12:04 PM
| | Master Motorized Bicycle Builder | | Join Date: Mar 2008 Location: Treasure Coast, Florida
Posts: 601
| | Re: Expansion Chamber
Well I finally got the drill bit I needed and drilled the jet out 1 size to .028 #70. I took it out about 10 miles this morning and it made such a difference. I got rid of the top end sputter, and picked up 1 mph. I still have a midrange sputter, that I believe is the taper of the needle, but its not where I usually cruise so I am not going to try to retaper the needle. When it cools down I still have to pull the plug and look at it, but I am confident that I am there. The pipe is quite a bit louder than stock, and I have put some steel wool inside the baffle in the silencer to to try to force more exhaust around it thru the fiberglass and back into the baffle and out the stinger, rather than having a strait path out, and made quite a difference....
Got it all painted with high temp paint and am ready for summer.....
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Last edited by misteright1_99 : 06-21-2008 at 12:06 PM.
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