Vulcan 500 Bluing on Left Side Exhaust Only?

coldblooded said:

Hey guys and gals;

My husband and I went to look at a 2009 Kawasaki Vulcan 500 (6300 miles on the odo) today and everything looked pretty good aside from slightly dry rotted tires and the exhaust - which was blue on the left side only (and gold on the right).

The seller claimed that it was recent and from idling the machine for an extended period of time. However, my research has indicated that there could be a lean condition on that cylinder.

From the reading I have done, bluing can be normal on certain bikes. However, I am concerned that may not be the case for this particular bike since it is occurring only on the left side. The bluing was pretty severe, it wasn't just slightly blue tinged.

Does anyone have any experience with this, especially on the Vulcan 500?

My main question is - is this something that we should immediately pass on, since this will be our first season and we do not want to have to mess with a carb rebuild or burned up piston?

We really appreciate your help! Thanks in advance.

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Yea.It indicates that ist is running very lean.Possibly from idling too long.I think I would pass unless very cheap.You would to do a carb rebuild or worse (Burnt valves)

Blaine said:

Yea.It indicates that ist is running very lean.Possibly from idling too long.I think I would pass unless very cheap.You would to do a carb rebuild or worse (Burnt valves)

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Like Blaine says, one of the cylinders is leaner and the excess bluing could very well be from idling too long. I've read the air induction system (AI) on some bikes can cause premature bluing of the pipes, especially if idled for extended periods. I have the same condition on my (third owner) 500 (one pipe very blue, one gold colored), but it has adequate compression and a leak down test showed no valve leakage whatsoever. It also runs fine but I disabled the AI to reduce further bluing.

One of the plugs on my bike also indicates a richer mixture than the other and no amount of carb cleaning, rebuilding or adjustment has changed that, but it has delivered almost 20K trouble free miles.

Buying a used bike is always a gamble. Good luck.

redfish said:

One of the plugs on my bike also indicates a richer mixture than the other

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Something wrong there. Have you vacuum synced the carbs?
Is one plug showing a little lean and the other OK or is one OK and the other richer?

Also, a general question. I am curious as to why idling causes pipe blueing?

sfair said:

Something wrong there. Have you vacuum synced the carbs?
Is one plug showing a little lean and the other OK or is one OK and the other richer?

Also, a general question. I am curious as to why idling causes pipe blueing?

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Just about vacuum synced those carbs to death chasing this down!

#1 plug shows black electrode, #2 is normal light brown.

Both exhaust pipes are (very) blue.
#1 pipe bluing extends all the way to within 12" of the muffler input and has areas of "gold" coloring.
#2 pipe bluing is slightly darker and extends to within 8" of the muffler input.

I owned a Triumph twin at one time and read (on the RAT forum) many posts that pipe bluing is made worse by idling too long (on AI equipped bikes). It was recommended the AI be disabled to lessen the pipe discoloration (something to do with the added air causing hotter exhaust gasses). Now I know to take a lot of forum member's opinions with a "grain of salt", but this observation was never challenged to my knowledge, and as you know, there's always someone out there to keep you honest or offer a differing opinion. If this is a false observation, it was never disputed.

I don't worry too much about the bluing on pipes. Yes it is an indicator of other issues(and you should investigate those causes), however those issues need to be much more severe before they cause engine damage. A little lean but well within the safe range where a bike might be jetted from the factory can in some cases start to blue pipes, but it is a long way off from burning up a piston/valve.

My '99 has a blued left header pipe. Compression and leak down test passed with flying colors. Someone(PO?) had been into the carbs and biffed the float height while they were at it.

Carb work is what it is(it's part of owning a carbureted bike), it will likely have to be done at some time on any carbureted bike you buy. May as well start fresh with a carb rebuild knowing it is right from that point forward.

Generally the idle air/fuel mix is on the lean side on most factory bikes in a attempt to lower emissions.

One of the first things I did was to block off the air injection system.
http://lamponedesigns.com/shopping_...ndex&cPath=2&zenid=1q53748rlfmd5jfm0rpbb6vsh2

Make sure that the rubber boot between the hot carb and the cylinder is sealed tight enough to prevent air bypass. My son bought an EN500 this spring that had set for several months in a garage and after reattaching the carb boot, it had an air leak because the coiled spring around the boot and the steel spring clamp were not tight. By the time he rode it back home the right exhaust pipe was blue and right cylinder was very hot. After we reattached the boot, it ran normally with no more issues. Just a possibility.

Hey, everyone!

First of all - thank you for the great information. We are still learning and this thread has been immensely helpful.

We decided to pass on this particular bike, it just didn't feel right. Here's hoping we can find a nice 500 or 750 here pretty soon.