Cracking exhaust noise 85 GS550ES

[Danjal]

So this just started a while back. It only happens at higher RPM's say 3000 and above and its not a constant sound in terms of time. About every 2-5 seconds in between. It comes from the exhaust also, and only the exhaust. Right out of the muffler. Any clues on it?

[chuck hahn]

Any new pinholes or loose clamps between the headers and pipes?? might be sucking a bit of cold air and its popping in the cans???

[Danjal]

Not that im aware of yet. I'll take a wrench to the bolts and see if it clears up. Are there gaskets between the headers and pipes by chance?

[chuck hahn]

Yes there should be two gaskets and two chrome collars with a bolt to tighten them around the pipes. Have you been to any of the parts fiches like bikebandit.com yet? all the schematics and prices for available parts are there..

[Danjal]

Yes there should be two gaskets and two chrome collars with a bolt to tighten them around the pipes. Have you been to any of the parts fiches like bikebandit.com yet? all the schematics and prices for available parts are there..

In the past yes, but not for this fix. Im still trying to identify this problem as is.

Thanks for your help Chuck.

[chuck hahn]

cool air sucks into tiny cracks and pinholes..since it is very oxygen rich it mixes with unburnt gas molecules and the heat ignites it inside the cans and makes those little crachling or popping sounds...thats the physics behind what happens....

[Danjal]

Makes enough sense.

On a side note.. Iforgot to add in here I have a 4-1 exhaust, unknown make, but the muffler is a pro sport. Lots of mods were done by the PO. I just picked it up cheap and got it to run again. It was one of those "sat for 10 years then bought by a guy who dosent know bikes then bought by me" deals. It had some interesting electrical problems and carb problems when I first bought it.

All I know for sure it has after market is:
4-1 pro sport exhaust
Dynojet stage 3 kit
2 K&N individual 2-1 pods (For the weird BS series venturi carbs.)

[Larry D]

Not that im aware of yet. I'll take a wrench to the bolts and see if it clears up. Are there gaskets between the headers and pipes by chance?

Part #4 on the on-line fische. A little pricey but, if you shop around some, you can find it a little cheaper. It's basically an exhaust gasket made of woven metal of some sort that sits inside the pipe and seals between the connections.

EDIT :: Nevermind, though you had a stock exhaust.

[Danjal]

EDIT :: Nevermind, though you had a stock exhaust.

Yeah, I keep forgetting its not stock. It makes troubleshooting and finding parts fun to say the least.

[chuck hahn]

are the 4 into 1 a one piece construction and welded where the headers and the can all meet up? I know my buddie V&H are two piece and the can just slips over the headers..I suppose that if its suckingb air there it could casue the same syptoms.. How about the baffles? They in or out?? could be a few things at this point. Got a good seal at the head and the pipe headers???

[Danjal]

Its welded together. The only place for air to leak on it would be where it bolts up to the head. I cant answer the rest until I start poking around. Id imagine the seals just up broke recently. It ran fine in warm weather, had no problems at all, but starting it to lube the internals up while its been sitting showed this problem.

[chuck hahn]

If the baffles are in and not loose and there are no missing screws that hold them in and so on..I would suspect a very small crack in the weld..inspect the welds very closely and look for any blackish carbon stains that may have leaked out and stained the pipes. if thats the problem then just reweld over the cracked area and call it good..let us know what you find.

[Guest]

Pull the spark plugs. Are they white as snow?

[Danjal]

Ok, sorry for the late update here. I just finally have time and room to work on the bike... that and its not -10 and snowing. Woo hoo.

Fired it up and ran it, the cracking started again, when it did the exhaust would push harder against my hand. So im going with the holes in the exhaust and guel igniting in the exhaust system. I cant see exhaust coming out if it anywhere other than the end.

Once it cools down I'll start checking and pulling stuff. For S&G I bought a new set of exhaust gaskets, so its getting those anyway and I'll check the muffler and pipes over when its off.

The plugs might not show me much of anything.. I just put them in before I garaged it. I'll pull all 4 and give em a look anyway.

[Danjal]

OK, cylinder 1 gasket was leaking. 2 & 3 were fine, and #4 was a replacement that was pretty crushed in there my the PO The headers were dinged up too where they mate to the gaskets. I tapped it lightly and buffed it smooth again on the wire wheel. The original gaskets I beleive were copper colored, and the replacement one was white, as were alll 4 of the ones I put in there. Its a 2 piece, and kinda loose fitting exhaust system, at least the muffler side fits on loose. So more then likely i'll need to get it welded. The plugs were all clean still. No soot no nothing.