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chuckr
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VBMWMO #9187
Joined: 10/20/2016
Posts: 30

hi, I have a 72, R75/5 with 30k miles. Somewhat new to me - PO had serviced the carbs. Bike runs very well, starts easy and idles pretty good and around 1200. When I inspect the plugs - one is tan one is a bit sooty...seems like one is too rich?

1. should I leave it?
2. should I tweak that carb?
3. should I baseline and start from scratch (never tuned these carbs but seems simple enough).

thanks Chuck

  • img_6173.jpg
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Chuck R
1972 R75/5, '69 2002, '82 528e
NY

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6540
I vote for Option 3.

I vote for Option 3. Shouldn't rely on the PO for this. Carb synching should be done after a 30 minute ride. Various methods out there - differential pressure gauges, manometers, plug shorting. They start with idle mixture setting, idle speed, finally cable tension. Always use one or more large fans blowing across the cylinders while you do the work. The engine requires air flow to pull heat off...without it, you can cook the engine.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

khittner
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VBMWMO #8223
Joined: 02/15/2012
Posts: 369
Your bike's crankcase

Your bike's crankcase breather probably dumps all of its oil vapor into the right carb's intake, which will create more deposits more quickly on the right side plug. Did the darker plug come from the right or left side cylinder? Your carbs may both be well-tuned, and you'll have different deposit patterns on the two plugs after some use. Others with more experience and better judgement than I can weigh in on what's in the range of "normal" for right-to-left plug appearance variations.

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Konrad

chuckr
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VBMWMO #9187
Joined: 10/20/2016
Posts: 30
Hi Konrad, hmmm, the sootier

Hi Konrad, hmmm, the sootier plug was from the right side...

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Chuck R
1972 R75/5, '69 2002, '82 528e
NY

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