BMW K bikes (Bricks)

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1Back to top Go down    Front exhaust pipe red hot at fast idle on Thu Feb 23, 2017 6:28 pm

Johnser

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So I woke the k100 up in anticipation of taxing it in march. I don't have a lot of private road to play with so was just going to start it up for a short while, drop the oil and let it drain overnight.

After it had warmed enough to idle happily, I set it at a fast idle, maybe 2000-2500rpm for a minute before dropping the oil.

But when I bent down to check the drain plug size, the front header pipe was glowing red. Not crazy bright but a good, dull red.

Suspecting a poorly seated or burnt exhaust valve, I pulled the plugs and did a compression test, all pretty good:
1(front): 190psi
2: 175
3: 185
4: 195

So certainly no issues with a loss of compression on #1. #2 seemed a bit low compared to the rest but a bit of oil on the bore brought it up to over 200psi so hopefully nothing head wise to worry about there although the oil could easily have sealed imperfections in the valve seats as well as around the rings.

So, other stuff I'm thinking about to investigate at the weekend;

-Maybe an air leak, leaning things out
-go for a covert run and see if it gets very hot or shows signs of being lean on the plug on an engine cut.
-Double check timing, am running a tad more advance than stock but generally fill up with the higher octane stuff.

Any other thoughts or things to check?

Maybe that's just normal and that pipe runs hotter due to unequal length headers? I don't know, it was all running fine when I tucked it away

Cheers

    

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