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Thread: Overheating Question

  1. #1

    Overheating Question

    My 1980 R65 has one head getting hotter than the other. Carbs were rebuilt and sync at idle. but when the throttle is applied there is a drastic change / difference. I checked compression, adjusted valves and confirmed there werent blockages in airsupply or exhaust.

    Am I missing something simple?

  2. #2
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    Quote Originally Posted by trianything1 View Post
    My 1980 R65 has one head getting hotter than the other. Carbs were rebuilt and sync at idle. but when the throttle is applied there is a drastic change / difference. I checked compression, adjusted valves and confirmed there werent blockages in airsupply or exhaust.

    Am I missing something simple?
    Did you also synch off idle, that is, with throttle twisted a tad?

  3. #3
    Liaison 20774's Avatar
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    Welcome to the forum! Carbs were rebuilt and are you sure that the needles are positioned the same? I don't know the setting off hand, but usually what you can do is measure the amount of exposed needle to be sure they're the same amount.

    You could also have a leak creating a lean situation. Try spraying the carbs with something like brake cleaner and see if the RPMs change while at idle. Maybe the carb-to-head rubbers are cracked or a clamp is not tight?

    Also make sure that the carb enricheners are completely off.
    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!

  4. #4
    Thank you,

    I plan to run down he list of all your suggestions.

    I replaced one pin due to pitting. I will be disappointed if I placed it wrong but very happy io get her up and on the road.



    Much obliged.

  5. #5
    Registered User lkchris's Avatar
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    Carbs "rebuilt" MUST include new diaphragms. Should include new needles, as they wear. (Fuel/air mixture is abrasive.) When the needles are both set the same height, THEN it's time to synchronize at 4K rpm.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  6. #6
    Rally Rat 1074's Avatar
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    Change in temp between the cylinders indicates cables are not in synch above idle.
    Boxerbruce

  7. #7
    Registered User donbmw's Avatar
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    Even with all the carb syncing donít expect the cylinders to be the same temperature. With my experience on aircraft engines very seldom do you have cylinders the same temperatures in CHTís and EGTís. On a motorcycle the direction of the wind should have a factor on the cylinder temps LH to RH cylinders.
    1975 R90/6, 1980 and 1982 R65, 2015 Ural Patrol, 1959 TR3A Triumph Car

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