[dayoffdave]

G'day all.

I'm hoping someone here can help me and who has the same Cobra Speedster Slashdowns pipes as I do to verify if there is a metal tube sleeve in each pipe near the power port crossover. You might have to remove one baffle out and flash a torch down the pipe to see what I'm talking about.

If you look at my rough sketch of my pipes you'll see that the metal tube sleeve I'm talking about is drawn in red and goes into the baffles about 15 to 20mm.
I want to know if that's normal for these pipes?

By now you'll be asking Why?
Well, a while ago last year I had some custom quite baffles made up.
They did the job of toning the sound down alot but now I want to go back to loud stock Cobra baffles for a while to gain more power.

When I went for a blast I notice a slight flutter or a churning sound on decelerate with the Cobra baffles in.
My bike never made that sound before the custom baffles was put in and I couldn't really hear that flutter sound with the quite baffles on.
I went back to the shop who made the custom baffles for me and ask him if he put those metal tubes in or not?
But after all this time he can't remember what he's done to my bike.

I also did the Bluey clutch hub fix roughly at the same time.
In the back of my mind I wonder if the hub could be making that flutter sound on decel. I left the springs in the hub abit loose so they can spin alittle.
But I really think it sounds like an exhaust sound problem that's in the pipes.
I did take off the exhaust from the headers and start up the bike for 30 sec's to hear if it would make that flutter sound on decel. I couldn't hear that sound coz the bike was spitting blue flames and popping a fair bit. So I shut it down before I can damage the valves. I hope I didn't stuff up the valves!

So there u go. That's my story of a problem that I'm trying to sort out at the moment.
Any help out there would be much appreciated.

Cheer's.

 

[dayoffdave]

Don't worry about looking at your pipe's. Found out it's normal to have that metal tube in there and it's welded in there. My drawing is a bit wrong also.

I just got to keep narrowing down the flutter noise and hear where it's coming from.

Cheer's.

 

[Zoom]

I've had 3 different types of mufflers on mine, and a couple variations of each one, and they all make that fluttering or huffing sound on deceleration. If the pipe is quiet you hear it more, or if you're decelerating adjacent to a hard surface like a bridge or wall you can hear it more. Pretty much all V-twins I've ever heard make it if they have a more open pipe on them, including most HD's.

I don't think you can get rid of it unless you have a really quiet baffle in the pipe. It's definitely not the clutch hub doing it, it's just air being sucked back into the exhaust. The only thing that seems to reduce it, but doesn't do away with it, is blocking the PAIR valve.

 

[bykman]

Same pipes with Thunder monster baffles. Yep it does it shift aroun 3800 she sounds Bad

 

[dayoffdave]

I took my exhaust off and pull it all apart. I notice alot of carbon build up on the inside of the heat shield's where the muffler joins are.
I reckon from all the extra back pressure from the custom quiet baffles has force a gap through the joints.

When I reinstall the exhaust I'll use new gaskets and hi temp silicon for the muffler joints. See if that will fix that bull**** sound.

My pair vales are blocked off with marbles.


Let u guys know what happens after that.

Cheer's.

 

[dayoffdave]

I did notice some burr's & a small lip near the power port. So I got the Dremel out with the long extension and grind them down flat. Those burr's and lip might of add to the noise that I was hearing but not really sure.

Anyway with the grinding & new gaskets the bike is all good now and purrs on decel which sounds a lot better.

Cheers.

 

[Skullster]

Wow I wasnt aware that they had a crossover pipe..cool more hp's right..

ps... piss test the pope :joke: