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Header pipe glowing

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On my s model the pipe backfires off the throttle and starts glowing when I'm cruisin in first through my neighborhood.

It starts up great and runs strong. Just did valve inspection. And carb clean. It has previously had jet work done and a fmf muffler with stock header.

When cleaning the carb I noted what had been done. Has 150 main jet. 25 pilot and what seems to be the stock un-adjustable needle with what seems to be a spacer on the needle.

What could cause my header to glow like this just cruising in low gear? It's even 50f degrees out

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Header glowing is pretty common.  Usually happens with the motorcycle standing still.  Since it occurs with no real load on the engine it is not a jetting issue.

 

150 main and 25 pilot sounds reasonable with the stock needle.  All needles have spacers.  You will have to compare the spacers to stock to know if the needle has additional spacers.  Post a picture or description of the spacers and where they are located (above or below the fixed clip on the needle)

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I'll have to pull the carb again to get a picture, but I did compare to stock diagram an there were definitely added spacers below the clip.

Starting from the clip down it went :

Clip

Skinny washer

Plastic white thicker spacer

Skinny washer

Skinny washer

I actually removed one of the last skinny washers and it still runs strong and still gets cherry red header while cruisin slow through the neighborhood.

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Should the fuel screw need to come out more to richin it up. I think I have it at 2.5 turns out now. For the header pipe to be turning red glowing while riding that means it's lean right. And the back firing and loud pops off the throttle could me the same?

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Spacers under the needle clip richen the mixture. I believe you had 2 added washers and reduced that to 1 by removing 1. With a 25 pilot jet, I don't think you are lean there.

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How's the headpipe to head seal?  Even just a slight leakage with a rich condition will cause backfire. Glowing header, like Noble says is common.

Edited by bucket list
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Spacers under the needle clip richen the mixture. I believe you had 2 added washers and reduced that to 1 by removing 1. With a 25 pilot jet, I don't think you are lean there.

Ok, my worry is that the bike is glowing while riding. I know it common if it sits there. Also it's like 50 degrees here so it's not exactly hot out either. Just the bike has some knarly back fires and pops.

I'm going to check the seal from header pipe to head see how it's looking.

Also I think this fmf has be either unpacked or lost a lot of packing. Wonder what that could cause minus loud ass bike. I'm going to pull it off and put some fresh packing in her.

I just had to adjust the valves they were getting tight and only at 7,500k miles , and I'm just worried it's running to hot or something and really want to figure out what the the problem is here.

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Header glowing is pretty common.  Usually happens with the motorcycle standing still.  Since it occurs with no real load on the engine it is not a jetting issue.

 

150 main and 25 pilot sounds reasonable with the stock needle.  All needles have spacers.  You will have to compare the spacers to stock to know if the needle has additional spacers.  Post a picture or description of the spacers and where they are located (above or below the fixed clip on the needle)

 

Good point.

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It's gotta be something, the header seal is good I just checked it.

I understand glowing is normal while sitting, but I'm riding !

did any one read my previous post ?

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So if it's not in he jetting could anything else cause the header to glow while riding ?

Poorly packed fmf?

Old air filter.

I just adjusted Valves I just dropped 1 shim size on all 4 and they are right in spec.

The exhaust gasket it good.

New cr8e plug .

I just want to get this bike ready for a long trips.

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My theory is the cam timing allows a lot of after burn in the exhaust, the exhaust is single wall pipe not very thick. So it easily gets hot enough to glow dull red.  There is a flame inside the exhaust.

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A little glow is normal as cherry red is ~1300-1400 deg. A lot or really bright is too lean. I had a wr that glowed so red you could see it at stoplights. Up two sizes on the pilot fixed the issue.

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Thanks everyone, seems I've confirmed the pilot jet size I think it's good. I'm going to go ahead and just change the header pipe gasket. Doesn't look to have ever been changed.

And maybe it's also because I am just going to slow at 10mph.

Thanks again!

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What is your carburetor off of? Is it a standard old Mikuni carb or a Keihin FCR?

EIther way sounds like you're running terribly lean. What does your spark plug look like? Let it idle for a bit then check the plug.

 

If you have an FCR check the plate on the front of the flat slide inside of the carb for damage. The edge of the plate broke away on my friends FCR which made it run really lean and caused the header to glow.

Also look all the way around both the boots either side of the carburetor to make sure they're completely sealed. When its sitting idling you can try spraying some sort of flammable aerosol around the boot areas and see if the revs change.
I'd avoid riding around until it is fixed.

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I have the stock bsr mikuni carb still . Checked all boots and etc. I did change the header pipe gasket it actually looked like it may have been slightly leaking from here. So it's changed out and took for another spin. Still have tons of back fire on decel but runs strong.

Haven't checked the new plug I recently put in. I also noticed that the header still get glowing at lower speeds in 1st hear just not as bad.

I have the fmf slip on I just repacked. Stock header. Carb cleaned runnin stock needle with a spacer and a 150 main 25pj and 2.5 turns out on mixture screw and 3x3mod done.

Edited by 250Smoker

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My header pipe has never glowed , ever, it's NOT normal.   2.75 turns out would help, but not much.  

You need a JD or DJ needle in there.   I would get a JD kit & call it a day.   :thumbsup:  Keep jetting as-is, accept for 2.75 turns & blue needle clip#4.  :ride:

Edited by Throttle5

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