Solo to Sidecar by STD

[Bruin]

It is a single cylinder/twin exhaust engine. The 2 head pipes are 1" ID, the left is 18 3/4" long, the right is 13" long, then they join into a 1 9/16" ID single exhaust pipe.

[coloradojay]

The XR 500 engine seems to be fairly popular with some flat track/ speedway racers. Maybe you can get some low buck exhaust info from them.

I'm loving the build so far. I initially started watching because I was planning on running a side car next year, but decided on building a new motor and getting the current set up dialed.

I teach high school English, so I know what working with a tight budget is like! I also ordered a copy of the book, and can't wait to start reading.

See you on the salt!

[Bruin]

Thanks coloradojay. Getting your main frame bike running up to snuff is a good thing to do before getting jiggy with it. Don't grade my book on anything but the story telling, I was a lackadaisical English student. Please do say Hi on the salt. It is 16 degrees in Topeka right now. No garage time for this gnome.

[tauruck]

Brian, I think Math is more important for this exercise.

I think you'll get more pleasure out of your sidecar on a limited budget than if you commisioned 5 guys to build you a $100,000 ride.

That's the spirit I believe. This game keeps you sharp 24/7 and you will squeeze every drop out of the project.

I'm subscribed.

[Bruin]

Tauruck, You get it. Our little team takes pride and satisfaction in doing what we can with what we have, can cobble together, or scrounge. We've been "making do" at Bonnie for six years now and few have more fun per dollar than we do. Our home designed and hand built sidecar will be a hoot at any speed.

[Hellcat Customs]

A "Sidecar Central" Would that also include "Wheel on a Stick" racers???

Bak, would you do the honor and be the first to start the sidecar coalition thread then?... Fir all us sidecar loonies?

[wobblywalrus]

The "tuned length" of the system you have are the distances between the exhaust valve faces and the expansion point where the two headers meet.  That length will be the primary influence on exhaust system harmonics.  The total length is the secondary length.  It affects system performance, too, but to a lesser degree.

The critical factor that has to be right for everything to work is that primary length.  Various formulae and Pipemax can give you that length.   

[Bruin]

Bo, so as I am understanding it, the twin head pipes, now stock at 18 3/4" and 13" x 1" ID...Should be 27" each and 1.74" ID? That means that I have no chance of tweaking a stock exhaust into an ideal tuning configuration. Without the means and skill to fabricate/buy one, ideal will just have to remain an idea.

OK, on to plan "B" How to cut a stock pipe so that it has the potential to help a tad at best, and not hurt performance at worst. EV Engineering suggested a 30" pipe. I can easily make an adjustable pipe sleeve to play with the length, and I have an open megaphone made out of a cut down stock muffler (With a single 90 degree shower drain baffle.) that I can play with. These will give me something to do trial and error with on the salt pending further "making do" input.

[wobblywalrus]

Bruin, today was our monthly Triumph Club breakfast and a fellow there used to build and race those Hondas.  He gave me these contacts www.billspipes.com and www.jemcoexhaust.com

What I would do is give a good pipe designer my engine and use info and have the pipe made.  The double exhaust ports complicate matters and make it hard for a home builder to get it right.

[Koncretekid]

You could just cut the head pipes off just before they join and extend each of them to the same length.  1" thin wall tubing is easy enough to find, but you have to use a mandrel bender to keep from crushing it.  I have a home made tube bender, but had to buy the dies.

BTW your camshaft is designed for mud riding or trials.  Take a look at Megacycle's catalogue someday to see their racing profiles.

Tom

[Bruin]

Thanks guys, I do like knowing the high end options, you never know when Santa might change his mind about me. I'm sure a race cam would help a lot. Worth pricing anyway. Pipe inserts to lengthen the 1" headers is a good idea. Depending on clearance they might not have to be bent. Question 1: The pipe formula suggests length AND diameter. If you only adjust length, will the unchanged diameter invalidate your efforts?
Question 2: I blew the original engine up and replaced it with an ebay special. I know better than to assume it is the same engine the seller claims. (without papers) Is there a master list I can compare the engine # to for the year and model? I'm suspicious because I found out that the replacement does not have the duckbill reed intake the original one did. It has a nice smooth open intake. Could I have stumbled across the street version? (XL?)

[Queeziryder]

Hi Bruin,
just to stir the pot a bit more, don't forget the Honda XBR500, which was a cafe racer stlyed road bike with wire wheels.
This had a hotter cam and a bigger carb setup from the factory.

All motors were based on the same RVFC 500 motor.

HTH
Neil

[Old Scrambler]

Bruin............take a look on ebay for a set of street-pipes from the FT500 Ascot model. Its two into one but the TWO are about the optimum length. That would change your exhaust to a low-pipe but may help the MONKEY riding position.  I agree on the cam.............and while your inside........don't forget to skim a few thou from the head and think about a thinner headgasket from copper.

[wobblywalrus]

The pipe tuning depends on the cam timing among other things, so it is best to figure out what cams to use before tuning the exhaust.  Hotter cams with more overlap and duration are going to be more sensitive to exhaust and intake harmonics.  The best source of info on what pipe to use is the person who developed the cams.   

[wobblywalrus]

Here is what I would do.  This took some digging around.

First, extend or shorten the headers to get the correct length for the desired rpm.  Pipemax seems to give the best lengths based on my experience.  Do not worry about header diameter.  The headers will be next to each other and parallel to themselves with different end points.

Second, build a can around the header ends.  The headers can project into the can different distances.  A 3,000 cc can volume should be OK.  Use the shape on the attached.

Third, use any end that is not restrictive.  It does not need to be a fishtail although one would look spiffy.

It was a good point that was brought up previously.  Mild cams do not benefit a whole lot by sophisticated meggas, etc.  Dumping the headers into a can will work just great.