Author Topic: Is it running lean?  (Read 927 times)

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Offline mrblasty

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Is it running lean?
« on: November 11, 2005, 12:30:01 AM »
Here is the deal, when I got the bike it had one pipe that was golding. Since thenĀ  have rebuilt the carbs and welded up the holes in the exhaust(stock exhaust), checked the intakes for leaks by spraying WD-40 while running the bike and noticed no change in rpms.
In dealing with the exhaust holes I shined up the head pipes by scrubbing them with steel wool and WD-40 that removed the old golding. Is it possible the chrome is "tainted" and now predisposed to golding? The plugs all read good, tan tips.
What can You guys tell me?
Here is a pic. It looks like they are a 10 or 14 on the spark plug catalog posted on dansmc.com
« Last Edit: November 11, 2005, 01:21:15 AM by mrblasty »
I farted and made my son cry.
1973 Honda CB 750
1975 GL 1000
1975 Yamaha XS650 The Swamp Donkey

MetalHead550

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Re: Is it running lean?
« Reply #1 on: November 11, 2005, 06:02:26 AM »
That looks ok, not lean.  Is that after idling though?  The golding must be due to a lean condition in that particular cylinder in the upper throttle range.  Id say cruise at the speed you usually average at and do a plug chop.  Youll probably find different plug readings.  Later.

Offline TwoTired

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Re: Is it running lean?
« Reply #2 on: November 11, 2005, 09:11:49 AM »
The plug deposits look decent.  But, Metalhead is on the right track, I think.  If your carb runs rich at idle and WOT and then lean through midrange, the plug deposits might "average" ok.

Head pipe discoloring is usually a sign of high exhaust temp and/or oil contamination, which can etch into the chrome.
If you cleaned with WD-40, it leaves an oil film behind, clean that off with alcohol or soap & water before they get hot again.

What about carb synch?  If one carb is open farther than the others, that cylinder will work harder/hotter.

In summary, if only one pipe is discoloring, there is either some surface contamination, or something about one cylinder is not operating the same as the others.
Is compression equal across the bank?
Is carburetion equal across the bank?  At all throttle positions?
Is filtration equal across the bank?
Is exhaust back pressure equal across the bank?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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