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Thread: Rough Idle, poor idle

  1. #1
    Registered User STEVENRANKIN's Avatar
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    Rough Idle, poor idle

    Hey all, just a note regarding a popular topic on the forum; rough or poor idle.

    My 84 R80RT recently started running rough and even. stalling at traffic lights and such.

    Put it on the bench, pulled the valve covers off and lo and behold, the exhaust valves were tight. Set them back to specification and idle is back to normal.

    So, a reminder; before messing with carburetors, do the airhead tune up mantra.

    Adjust valves first.

    Spark plugs, and points if you have them, inspect, clean and adjust. Make sure timing is right, point gap and condition effects timing so points first. For those of us with electronic ignition, timing for the most part won't change unless something drastic has happened.

    Finally adjust the carburetors. Be sure, there is slack in the cables to allow the carbs to be in idle. Carbs mixture doesn't change very much but, cables do stretch, and needles do wear out.

    So final point, poor idle is not always the carbs. Cheery bye, St.

  2. #2
    Quote Originally Posted by STEVENRANKIN View Post
    Hey all, just a note regarding a popular topic on the forum; rough or poor idle.

    My 84 R80RT recently started running rough and even. stalling at traffic lights and such.

    Put it on the bench, pulled the valve covers off and lo and behold, the exhaust valves were tight. Set them back to specification and idle is back to normal.

    So, a reminder; before messing with carburetors, do the airhead tune up mantra.

    Adjust valves first.

    Spark plugs, and points if you have them, inspect, clean and adjust. Make sure timing is right, point gap and condition effects timing so points first. For those of us with electronic ignition, timing for the most part won't change unless something drastic has happened.

    Finally adjust the carburetors. Be sure, there is slack in the cables to allow the carbs to be in idle. Carbs mixture doesn't change very much but, cables do stretch, and needles do wear out.

    So final point, poor idle is not always the carbs. Cheery bye, St.
    If the exhaust valves are tending to close up, then I suggest you keep an eye on this, lest you end up with $$$ problems. The 1984 was the last year of the valve seat problems.....the R80RT does not tend to have the problems nearly as much as the R100RT....are your valve seats the originals?
    http://bmwmotorcycletech.info/valves.htm

    Snowbum

  3. #3
    Registered User STEVENRANKIN's Avatar
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    One set done awhile ago

    Oh yeah, I was bit by the valve recession bug back in the early 90's. This is more of a normal service interval thing.

    Just trying to get the word out on what to look for if you have rough idle and where to start.

    I defer to Snowbum as the known expert, does my advice make sense? St.

  4. #4
    Liaison 20774's Avatar
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    Makes sense to me, Steven. Even before I finished the first couple of sentences, the words "valve clearances" was going off in my head! Always first thing to check for rough idle but bike seems to be OK at speed.
    Kurt -- Forum Liaison ---> 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!

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