My café racer all finished...

Jeandr · Nov 20, 2009

I worked on the exhaust pipes/muffler today. The long part of the perforated tube will be wrapped in fiberglas before being inserted in the megaphone. I hope they will be quiet.

The "muffler" in place, see, no tire warming :!: Now I have to make a bracket to hold it in place and add the tabs to hook the springs holding the pipes to the muffler.

Jean

grandpaul · Nov 20, 2009

HEY! That's cool! (on the rear tire, too) Definitely a unique setup. Is that system "tuned" for back-pressure, maximum efficiency, etc?

swooshdave · Nov 20, 2009

Hmmm...

I think a diverter inside the end of the megaphone would have had a similar effect and been less obtrusive.

Jeandr · Nov 20, 2009

No tuning, flying by wire here :lol: One reason to make it that way is to avoid getting a ticket for being noisy. When the cops make spot checks, the first thing they do is to see if the pipes are straight through, they jam a coat hagner in the pipes, if the wire goes in easily, instant ticket. The way I made the muffler, there is no way they can jam a wire in. I think they also use sound meters, but only as a last resort.

I thought about putting Supertrapp discs on the end, but that is a bit too common. Also, Supertrapp discs exit all around, OK at the end of a bike, but no so under the engine.

As for being "obtrusive", I calculated the surface area at the collector (1½") and calculated the surface are of one hole (¼") and came to the conclusion I needed 144 holes not to restrict flow so I used a few more just in case. I think it should work out. Al painted black it should be cool

Jean

bpatton · Nov 20, 2009

Jean, That is Super. What's the length of the headers to the junction? I've been reading Smith and Morrison. Their methodology is a crack up by today's standard, but none the less accurate for it.

jughead · Nov 21, 2009

Man you gota video it running ,with sound and put it on Youtube. I just gota hear it running. :shock:
JUG

Rich_j · Nov 21, 2009

Those exhaust parts are beautifully made.

Is such a short pipe going to work well? Most tuned lengths on Commando engines seem to be longer than stock.

Jeandr · Nov 21, 2009

bpatton said:
Jean, That is Super. What's the length of the headers to the junction? I've been reading Smith and Morrison. Their methodology is a crack up by today's standard, but none the less accurate for it.

As close as I can figure out, from 24 to 26 inches to the junction depending if the measure is on the outside or the inside of the curve.

Jean

Jeandr · Nov 21, 2009

Rich_j said:
Those exhaust parts are beautifully made.

Is such a short pipe going to work well? Most tuned lengths on Commando engines seem to be longer than stock.

Thanks, as for the lenght, if you look at the Steve Maney pipes, they aren't that much longer to the junction and they are trying to make power, I just want something that looks good and doesn't make too much noise :mrgreen:

Jean

I will try and make a video with sound befor ethe snow falls and I go into hibernation

Jeandr · Nov 22, 2009

Hope this works for you guys...

Here is a sound file of the exhaust taken at less than 2 feet from the right side without anything to dampen the sound inside the muffler:

http://www.fileden.com/getfile.php?file ... ORC004.wav

Here is a sound file with some fiberglass inside the muffler to dampen the sound

http://www.fileden.com/getfile.php?file ... ORC005.wav

Jean

RennieK · Nov 22, 2009

Oh man, if that's not inspirational... The fiberglass does flatten it out a bit but I'm not sure about db reduction.

That's a wicked pop sound (actually more like a crackle) that happens when you let off or level off. You don't hear it at idle or on strong acceleration. It's that short frequency crackle. I don't know the significance of this sound other than it seems to be an extra sound. I was trying to remember where I've heard it before and , are you ready for this, it is in the space shuttle launch only there it's constant under full acceleration.

One thing about the Maney pipes is he is running 1000 ccs. Your meg has a fast taper even though it's short.

if the cops check you maybe you could pull one spark plug lead off

jughead · Nov 22, 2009

I prefer the first one, no fiberglass. :mrgreen:

Jeandr · Nov 22, 2009

jughead said:
I prefer the first one, no fiberglass. :mrgreen:

Hooligan :shock:

I will try it with a better packing of fiberglass, I had a piece lying around and I didn't want to cut more, so maybe it will be a bit less noisy (I have some degree of civility :wink: )

Rennie, the sound files are not very scientific, and my MP3 player may have some kind of automatic volume control, but right you are, the sound is less raspy with the fiberglass

In my younger days, I had made a two into one somewhat like that with a muffler under the engine and one day I took the muffler off because it was only held with a hose clamp that always came loose. It wasn't too noisy so I rode like that for a good while until one day I was at a light when a cop pulled up two lanes over, he looked at me, at the bike and then his gaze went lower and he gave me the sign to stop on the side. He said "I see you don't have a muffler" and then told me the provincial fine was $30 but the city fine was $13, which one would I like :lol:

Jean

Jeandr · Dec 6, 2009

This week I painted the exhaust pipes and muffler and made the bracket to hold the muffler under the engine cradle. I managed to find the proper combination for the breather to work correctly. I can say that now it is finished :!: I will have to wait until spring to go further than around the block and get it licensed. To pass inspection I will have to put some temporary belt guards on both the primary and secondary belts and put on a temporary back mudguard.

Jean

Fullauto · Dec 6, 2009

Well done Jean. That is SUCH a nice bike.

GRM 450 · Dec 6, 2009

Thank you Jean I needed a new screen saver.

It's a credit to you.

graeme.

davamb · Dec 6, 2009

Wow. What a knockout Jean. Just brilliant.

grandpaul · Dec 7, 2009

HOOFAH!

Wow.

DonOR · Dec 7, 2009

Sweeeet!
I can imagine the humm of those belts compared to the clickity-clack of my chains... but with that 2 into 1, can you hear much of anything?

lcrken · Dec 7, 2009

That is a lovely job, Jean. Sorry if I missed this in the earlier posts, but what was the source of the alternator? Thanks.

Ken

My café racer all finished...

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