Solo to Sidecar by STD

[Old Scrambler]

Brian is very used to unchartered waters..........I'm reading his book...........just finished the chapter about the 'strip'-club and his older brother returning from 'Nam'. Its a good read about real life.........I recommend it Pass the word and help Brian go faster

[Hellcat Customs]

Sounds silly, and I'm way late with this post... But.... We are moving both our Fuel tanks to the sidecars behind the wheel and the pumps are inside the tanks so we don't have to mess about with valves or fire sleeve... Just a thought

I'd start a build thread myself but Turbo Harley sidecars don't gather much Intrest.... We sound start a central sidecar thread for the few of us who really love them... Or maybe a sidecar builders communication network or club so we can all learn from one another

[Nortonist 592]

The above sounds like a great idea.  We do need a "Sidecar Central" of some sorts.

[Koncretekid]

I am a big believer in not reinventing the wheel. If you can turn me on to any exhaust mod plans (Doable by hand tools based on the piece that I already have) I'd appreciate it. This stuff is uncharted waters for me. BTW, my XR500 is a 5 speed. I've got it geared tall enough now that I need all two miles of the mountain 0 course to get to 6,400 rpm in 5th. (106 mph)

Brian,
My guess is that you are geared too high.  That Honda should easily spin 8,000 rpm, and probably doesn't make max hp until you get close to that (I roadraced against one, and I couldn't get close to him on the B50)

A bike with a four speed tranny that is pulling a load needs a wide power band.  

In my opinion, you don't need a wide power band at Bonneville.  Horsepower requirements increase at the cube of the speed increase.  Even a bike with a very steep power curve will generally increase horsepower in a linear fashion.  Your maximum speed will be largely determined by matching your max horsepower to your maximum speed at your given drag. Experiment with different length straight pipes (very easy to do).  Panic's Victory Library has good info originally derived (I think) from pushrod British bikes, so I don't know if it applies to that overhead cam 4 valve "modern" Honda , , but it seemed to work for me.  I have attached a PDF which shows horsepower to speed requirements for my bike.  Look at the graph.  Unless your horsepower curve is steeper than this, you just need to read down your desired speed to see the horsepower requirement (for my CdA).  Match your gearing to your max horsepower RPM and give it a try.

I'd start a build thread myself but Turbo Harley sidecars don't gather much Intrest....

I think you'd be surprised at how much interest your build thread would gather!

Tom

[bak189]

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

[Bruin]

Good information fellas, I'll check it out. Anecdotally, when I did gear down for more top end rpm I lost a few mph. Granted it was not a controlled test. My shift point has been 7,000 on the lower four gears and top rpm varies between 6.4 K with a 6.7 K best. I had planned to gear down for the power needed to haul the extra sidecar weight and what has been discussed underscores the need for doing that in general.

An adjustable straight pipe has been suggested more than once and it is within my skill set. E & V Engineering recommended 30 inches.

Sidecar Central sounds like a good idea and I'm not prejudiced at all.

Thanks for supporting and recommending my book, the proceeds do help me get to Bonneville.

[tauruck]

Brian, all the best for your writing (sales) and on your project.
 

[Nortonist 592]

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

Of course Bob.   There would even be room for a M20 with AA sidecar.

[Koncretekid]

Just wondering what year your XR500 is?  I see that the '83 & '84 models were 92mm bore by 75mm stroke.  That is exactly what my modified B50 is, and with a Megacycle cam and 12.5:1 JE piston from Ed V., I can turn 8000 rpm all day, and I've seen 9000.  A piston and a cam would probably really turn that motor on.  But I know, you'd have to see a gazillion books to pay for them!  I will be ordering one when I get to Colorado for Christmas, if that will help.
Tom

[Bruin]

It's a 1984. I'm sure a piston and hot cam would give it some Umph. Nothing is more true than the old saw, "Speed costs, How fast do you want to go?"  But please continue the suggestions. I like to know what is possible.

Every book helps and so far people seem to like it. Thanks.

[JimL]

Speedway sells a plain steel megaphone section.  It starts at 1 5/8" and goes to 3" over a length of 30".  I use the section from 2" out to 2 1/2" for my megs, with a slash of 2 1/2" exhaust elbow to do the job of a reverse cone.

Meg part number is 91013372 for $35.  They sell lots of mandrel bent pipe to fab up your headers.  Ordered your book off Amazon..looking forward to it.  I wrote a book once...went nowhere because nobody was very interested in how to build a streetrod with a Toyota engine. ....still have a box of them in the attic...probably helps insulate.

C'est la vie 

[wobblywalrus]

Jim, I read and enjoyed your book.

Bruin, the rpm range you need power for includes the drop in rpm for the shift lag from 4th to 5th as well as the rpm range you plan to run through in fifth.  You also need to include some extra power band width to reflect the sophistication and accuracy of your tune.  Add all of this up and it can be 3,000 or 4,000 rpm, even on a five speed bike.

Open ended straight pipes produce the biggest power spike but it is over a narrow band with pronounced lack of horses on each side.  They work OK but a person really needs to have a dyno run to know the power curve shape, good info on gearing, the ability to match everything together, and lotsa sprockets.  It is much more difficult to make work than it seems.

As mentioned previously, Panic's Victory Papers have some good info.  That is what I have lost and cannot find anywhere.  He is a forum member.  You can make a pipe to his formulae and be close enough.

[Peter Jack]

Google Victory Tech Papers and you may find what you're looking for. ------------- No guarantees!!! 

I just did it and there's a bunch of stuff there.

Pete

[Bruin]

I didn't find specific exhaust pipe length info on Panic's Victory site but there is a lot to wade through. There is megaphone design info but it is a lot to digest for me. I need to study it more. I did goggle up a exhaust length calculator, I used stock figures that I searched up...BBDC-45, ATDC-5, rpm-6,500 and 500cc. It told me to use a 26" tuned length from valve head. But it also mentioned a 24.9" tailpipe length. I'm not sure what length they want you to use. It did specify a primary inside diameter of 1.74" but I can't play with that, I'm locked into what the stock pipe diameter is.

Apparently stock xr-500 hp is 32 @6,500

[wobblywalrus]

Is your 500 the one with a header pipe for each of the two exhaust valves?