White on the exhaust?

M

mg42gunner

Active Member
So I've been flying around on my cb750 'kind of cafe' for a little while and all was well, still ironing out a couple kinks. However, today after pulling back into the shop I looked at the pipes coming off the head and my #3 cylinder has an off white, almost tan color to it just around where it bolts to the head. The rest of the pipe is normally colored (save for the little bit of bronzing from my initial tuning error). I'm thinking it's just exhaust leaking around a worn out exhaust gasket. I was just throwing it on here to see if anyone else has any ideas?
 
Without some pictures I'm going to guess cupcake frosting.
 
Image pipe on right is the white one obviously. Left pipe is the way they looked yesterday. And I promise to stop eating bakery while riding the cycle from now on.
 

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Have you checked that spark plug. It might be running lean which is causing it to overheat and discolor the exhaust pipe.
 
Alaskanrocket said:
Have you checked that spark plug. It might be running lean which is causing it to overheat and discolor the exhaust pipe.
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This would not leave a white residue on the exterior of the header.
 
Rich Ard said:
Without some pictures I'm going to guess cupcake frosting.
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I'm going to stick with cupcake frosting.. Hahaha..

Seriously does look like some cleaning stuff burnt on... If you're worried about the tuning/running of each cylinder you should pull the plugs and check them. That will tell you for sure if the one is running lean or differently than the others. Quick easy check.
 
Okay so I pulled my pipes off because I planned on coating them anyway. There is white residue inside three of the four pipes. I can wipe it off with my finger... Ideas? I'm thinking maybe gasoline detergent build up? But then why in three out of four?
 

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Valves have the same white powder on them as well. I'm starting to think I'm a little lean as well now.
 

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Also... If the white residue ended up outside the pipe, then your exhaust gasket/pipe clamp isn't doing its job for one reason or another.
 
Its the mexican model - cb750 "smuggler"
They all have the powder inside the engine. Check the seat also ;)

Lean indeed.
 
Would someone enlighten me as to what the white powdery residue would be? I have not seen that before when something was running lean.

Bert Jan said:
YES!

I love it when you make my day!
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Nice to see you too buddy
 
You're in Alaska, there's a white residue on everything.

Anyway, like I said, I would like know know what that residue is, as I haven't seen it in the past.
 
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