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Thread: 1976 r75/6

  1. #1

    1976 r75/6

    This bike has about 4,000 miles on it since it Put it back in service a few years ago. I changed the points for a Dyna III. Valves are adjusted each spring and need very little, if any adjustment. I loosen the nuts on the exhaust each year for never seize but this is the first time they have come off (I am pulling the transmission to lube the splines). The bike runs great. It starts easily even when it is very cold outside though I do notice one cylinder is slow to get going. Once its warmed up for a couple of minutes it seems fine. The white valve is on the right side which is the same side as the crankcase breather. Can anyone steer me toward a cause / solution or do I even need to be concerned about this? Thanks.
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  2. #2
    Administrator 20774's Avatar
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    It would seem that there's a difference in the carbs...white usually means lean conditions; spark plugs are supposed to be a light tan but when they're white, that usually means their running hotter due to lean conditions. The engine breather dumps oil mist into the right cylinder...if it was doing that excessively, you would think that the right side would be darker.

    When was the last time you synched the carbs? Probably should be done. Could be that the right side is running hotter. Try one of those infrared thermometers and see if you can detect a significant difference.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Thanks for the follow up. I will pull the plugs and look at those as well. Will do a complete tune up including synchronizing the carbs in the spring when I get it back on the road. Thanks again.

  4. #4
    Registered User lmo1131's Avatar
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    spark plugs are supposed to be a light tan
    Does that rule of thumb still apply given the alcohol content of most fuel(s) now?
    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  5. #5
    Administrator 20774's Avatar
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    Quote Originally Posted by lmo1131 View Post
    Does that rule of thumb still apply given the alcohol content of most fuel(s) now?
    Not sure, but I still hear people mention it. Snowbum mentions to check the color of the base and insulator but no specifics regarding what color to look for. There is this page from NGK...has a date of 2016 on it.

    https://www.ngksparkplugs.com/about-...d-a-spark-plug
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  6. #6
    I run only ethanol free gas and I have been told that adding 1 cup of 106 octane aviation gas to each 5 gallons of ethanol free regular gas pretty much makes up what this machine was born into. Of course, I don't do that because it would not be legal. One plug is a nice tan color and the other is black and somewhat oily.

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