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Author Topic: Rusted Exhaust Pipe  (Read 1298 times)

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Offline billstron

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Rusted Exhaust Pipe
« on: October 26, 2006, 08:20:59 AM »
My '78 550 has 4-4 exhaust pipes, and the #1 cylinder pipe is badly rusted at the tip.  So bad that the exhaust doesn't come out of the correct hole, it comes out of the rust hole right below the correct spot.  The good thing is that it sounds cool, only to one ear though  :D  How bad is this?  I want to do a carb sync this weekend.  Will the hole keep me from getting a proper setup?  Also, I have smoke from that pipe.  Is it possible that there is any correlation to that rust?  I believe that it only smokes at idle.  Thanks...
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Offline SteveD CB500F

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Re: Rusted Exhaust Pipe
« Reply #1 on: October 26, 2006, 08:24:28 AM »
The holed exhaust will certainly screw up the carburation and would bean inspection failure over here.

The smoke isn't caused by the hole in the exhaust.
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Offline billstron

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Re: Rusted Exhaust Pipe
« Reply #2 on: October 26, 2006, 08:55:53 AM »
There is no way that the hole could cause that cylinder to run rich or lean, creating smoke?  I thought I saw somewhere that the wrong amount of combusting gas could cause smoke.  Maybe I misunderstood. 

Does the hole make less back pressure causing the cylinder to run lean? 
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Peter

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Re: Rusted Exhaust Pipe
« Reply #3 on: October 26, 2006, 08:58:38 AM »
THere are a few things to note.  

1 is that the location of the hole will determine the effect on the carb.  If the hole is at the end then the back-preassure shouldn't change that much.  If it by passes the baffles, that is another story.

The smoke could be a number of things, oil, dirt from the road, carbon deposits etc. Just sitting in the pipe
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Offline scondon

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Re: Rusted Exhaust Pipe
« Reply #4 on: October 26, 2006, 10:03:21 AM »
  Since the carb sync will measure the air vacuum of each cylinder on the intake stroke I don't think the hole in your exhaust will matter in getting your carbs to pull equally. The hole can affect how that cylinder burns fuel, as you suspect and Steve points out. A number of things can cause "smoke" to come out( as Peter points out ),if it's most noticable at morning start up it could be at least partially attributed to moisture collecting in the pipe overnight.I've got a compression tester if you want to check the health of that cylinder.

    Looks like Saturday around "noon-ish" is a good time to get started. Bring a manual if ya got one, I'm a little rusty on the 550's. Best to get the valves adjusted before starting the bike and riding over for the sync. Give me a call if you'd like some help with that procedure.
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Offline billstron

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Re: Rusted Exhaust Pipe
« Reply #5 on: October 26, 2006, 04:57:15 PM »
Thanks for all of your opinions.  It isn't a morning start up thing.  It is after the engine heats up, but still intermittent.  It seems like it does it more at idle after running under heavy load, but I haven't correlated it fully to that yet.  I have a shifter shaft seal leak that leaks onto that pipe.  Maybe that is getting in some how.  I don't know.  I don't know.  It isn't bad enough to make me want to do anything drastic, like take my engine apart.  Just embarrassing.  If I'm going to be riding something that looks like a POS, I would rather it not smell like a POS too. 
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