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General Category >> Rubber Side Down! >> Blue header pipes - sign of excessive heat?
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Message started by DesertCat on 07/18/19 at 11:47:11

Title: Blue header pipes - sign of excessive heat?
Post by DesertCat on 07/18/19 at 11:47:11

OK, I've had BMW boxers. I have 2 right now and their header pipes start to turn blue after a a couple hundred miles. I accept that because of the single-wall construction that BMW uses on their header pipes -- and they aren't chromed -- well the R1200C cruiser (infamous James Bond bike) has chrome header pipes, but that's the only boxer that does.

Does a blue header pipe on an LS650 mean anything? I've seen pics of LS650s with almost 10K miles and the chrome header pipe looks brand new. I've also seen LS650s with fewer miles and the header pipe is blue for a foot from the head. Is this a sign of excessive heating of the engine?

Is the LS650 header pipe a double-wall construction?

Title: Re: Blue header pipes - sign of excessive heat?
Post by verslagen1 on 07/18/19 at 12:19:34

Yes, it can indicate a lean running savage.
Although there are other reasons it turns blue too.

Yes, double wall.

Title: Re: Blue header pipes - sign of excessive heat?
Post by DragBikeMike on 07/18/19 at 12:44:35

It's a mystery. The aviation industry seems to be of the opinion that stoichiometric yields the highest exhaust gas temp. Only da Shadow knows.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1552607217

Title: Re: Blue header pipes - sign of excessive heat?
Post by norm92de on 07/18/19 at 12:45:45

FWIW My 2014 has almost 10000 on it and the pipe is like new. I live at 4000' so it runs richer than most, I also raised the needle a bit .035".

Title: Re: Blue header pipes - sign of excessive heat?
Post by norm92de on 07/18/19 at 12:50:56

DBM,
On aircraft we always leaned to max temp minus 25C on the lean side for best economy. however some engines didn't like to run that lean. I think it depended on your attitude when you set the mixture. ;D

Title: Re: Blue header pipes - sign of excessive heat?
Post by Dave on 07/18/19 at 12:59:03

The chrome turning blue is a result of a an oxidation of the chrome that occurs once it gets above a certain temperature. The funny thing is that if you go a "Google" search - you get lots of opinions but very few real facts from reliable sources.

I believe that the majority of Savages with blue pipes come from riding in traffic, excessive idling, starting the bike and letting it "warm up" for a few minutes before you head out, riding in really hot weather....anything that doesn't let air blow over the outer pipe to cool it down. The folks that like to start their bike and let it idle to charge the battery during the off season can have really blue pipes.

I am headed down my driveway about 20 seconds after I fire the bike up, I avoid aggressive riding and a lot of throttle until I get a few miles down the road and the engine has warmed up - and my pipe is nice and shiny silver after 12,000 miles.

I believe that our gearhead shade tree mechanics have figured that since exhaust valves, spark plugs and pistons can get burned when an engine is running lean - it must be running hotter. The exhaust temperature gauge shows that to be a wrong assumption in the exhaust stream.

I have never seen any testing and actual data to show that pipes turn blue because the fuel mixture is lean.......only shade tree mechanic opinions.

Title: Re: Blue header pipes - sign of excessive heat?
Post by DesertCat on 07/18/19 at 13:03:21

1E25283F2E22393F242C213E4D0 wrote:

I believe that the majority of Savages with blue pipes come from riding in traffic, excessive idling, riding in really hot weather....anything that doesn't let air blow over the outer pipe to cool it down. The folks that like to start their bike and let it idle to charge the battery during the off season can have really blue pipes.

========================

I remember reading on a BMW forum that a guy was doing that one night, then forgot or got distracted, came out and saw that his exhaust headers were glowing a dull red color. :o

Title: Re: Blue header pipes - sign of excessive heat?
Post by norm92de on 07/18/19 at 13:06:13

My Triumph Bonneville would do that. I only let it happen once. :'(

Title: Re: Blue header pipes - sign of excessive heat?
Post by verslagen1 on 07/18/19 at 13:17:06

26273A25717A2C2D480 wrote:

If you're flying on a savage you either have a big grin or you're sheeting big time.

Title: Re: Blue header pipes - sign of excessive heat?
Post by Dave on 07/18/19 at 13:20:02

My Sherco trials motorcycle had a stainless header pipe....in order to save weight it was very thin.

While riding the bike in the evenings you could see the header pipe glowing a dull red after climbing hills or doing anything that required you to have the engine wound up a bit for 10-15 seconds. Stainless is not as good of a heat conductor as plain steel, so it does not transfer the heat to the head or downstream to the muffler end - and the thin pipe made the condition even worse. The stainless would discolor as a result of this heat, and you needed to polish it once in a while if you didn't like a dark brown pipe.

One evening I was leaving the woods just as it was getting too dark to ride anymore. For some reason I turned around and looked back into the woods, and I saw a small orange glow. I went back and found some leaves on fire. When riding in leaves sometimes the front wheel would deposit them on the header pipe - and evidently I set one on fire and it fell off and was starting a small fire. Thank goodness I saw it or my whole woods may have burned!

Title: Re: Blue header pipes - sign of excessive heat?
Post by norm92de on 07/18/19 at 13:27:21

Versy,
I have never been able to find the mixture control lever on a Savage. it would probably distract me from looking out for traffic. ;D

Title: Re: Blue header pipes - sign of excessive heat?
Post by verslagen1 on 07/18/19 at 13:36:15

5E65687F6E62797F646C617E0D0 wrote:

I have never seen any testing and actual data to show that pipes turn blue because the fuel mixture is lean.......only shade tree mechanic opinions.

Dave, we have the same warmup procedure.
And I don't apply anything to the header to keep it shiny that might blue when heated.
When I got my bike it was stock for a 96 and the headers blued.
I rejetted and they went from blue to gold.

Title: Re: Blue header pipes - sign of excessive heat?
Post by norm92de on 07/18/19 at 17:17:54

I'm surprised. I have always thought that once blue always blue.

Does that mean it might return to chrome again?

Title: Re: Blue header pipes - sign of excessive heat?
Post by DesertCat on 07/18/19 at 17:22:46

There are several products on the market that claim to be able to rub the blue away. Don't believe them. You'll have just as much luck with any cheap sort of chrome polish, which won't work either. Oh, the pipes may look slightly melllower after you've worked on them for 30 minutes -- but as soon as you start the bike, the pipes are right back to the same blue as before. The blue isn't some surface thing, it's down into the metal structure.

Maybe some chemist or structural engineer on the board can explain the bluing of header pipes.

Title: Re: Blue header pipes - sign of excessive heat?
Post by justin_o_guy2 on 07/19/19 at 14:59:06

My showroom floor looking header turned blue in a matter of minutes when I was listening to the valves, gunning it up and letting off. It made five thousand miles, stock, and I screwed it up in almost no time.

Some of them turn blue because they need rejetted, some need someone to do something like I did.
Mine WAS lean, but not so bad as to blue the pipe.