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Old 09-02-2010, 09:00 PM   #1
dino1 OP
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Horrible noises from my airhead engine

1987 r80 unkown miles, oil pressure seems good, screechy noise when reving to 4K, sounds like an accessory belt slipping on a car. Gen light flickers when it happens. Any ideas? TIA
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Old 09-02-2010, 09:03 PM   #2
matman1972
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Quote:
Originally Posted by dino1
1987 r80 unkown miles, oil pressure seems good, screechy noise when reving to 4K, sounds like an accessory belt slipping on a car. Gen light flickers when it happens. Any ideas? TIA
check your alternator rotor/ stator. I'm wondering if they are hitting?


i'm betting main bearing. Shaft moves under stress due to worn bearing, rotor hits stator, and viola, lamp flickering. Check it out before riding.
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matman1972 screwed with this post 09-02-2010 at 09:14 PM
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Old 09-02-2010, 09:27 PM   #3
dino1 OP
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So is that bad? Or is that just like getting a new alternator? Not the main bearing for the crank correct?
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Old 09-02-2010, 09:32 PM   #4
zenben
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Alternator brushes worn out. About $3 to replace.
Check 'em quick, or you may have to buy a new rotor too.
Rotor may be slightly loose and cause the same symptom.

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Old 09-02-2010, 09:35 PM   #5
matman1972
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If you look at the picture, your rotor for your alternator rides on the front of the main crankshaft. When the bearings on the crank start to go, the crank will wobble, causing the rotor to touch the stator, making your gen light blink and making the noise you are hearing. Open up your front cover, unplug and remove your stator, and inspect it and the rotor. A new alternator will not do it, it will just wobble with the crank and do the same thing.

Buuut, I have been vodkaing up the lemonaid tonight, so someone else tell me if there is a simpler, less major cause I am overlooking.
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Old 09-02-2010, 09:39 PM   #6
matman1972
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Quote:
Originally Posted by zenben
Alternator brushes worn out. About $3 to replace.
Check 'em quick, or you may have to buy a new rotor too.
Orrrr, could be that too. That's what I get for offering alchohol induced technical info. That would be a muuuuuuuch cheaper fix. Same advice, pull the front cover and check them out. I will be praying for ya, My r50 was the bearing.

BTW, If I made you worry and it turns out to be something cheap, I owe you a beer.
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Old 09-03-2010, 08:59 AM   #7
DaveBall
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2 years ago had a very similar sound coming from the front of my 81 R100RT. Pulled the cover and found the brushes had disintigrated. Basically worn way past recognition and ground bad grooves into the rotor. There was also a bad electrical smell coming from it.

Could have replaced the rotor and brushes, which would have been cheaper, but as I had wanted to upgrade the output anyway, I replaced the whole charging system with the Enduralast system. Been extremely happy, and now much warmer on winter days.

So advice would be to check those brushes a little more often. Saves you $$ in the long run.
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Old 09-03-2010, 10:14 AM   #8
datchew
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Go read THIS
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Old 09-03-2010, 05:35 PM   #9
airheadpenguin
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I have a complete airhead alternator from a '78 R80 I believe. PM me if you need one.
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Old 09-03-2010, 06:21 PM   #10
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Quote:
Originally Posted by datchew
Go read THIS
Can I get the Cliff Notes?
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Old 09-03-2010, 08:08 PM   #11
dino1 OP
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Thanks for the help, I'll get into this this weekend, somewhat bummed when I heard the noise but hey I only have like 1K in the damn thing so if I need to tear it down for MB then I'll learn a lot more a lot quicker. But I'm hoping for brushes so I can ride it more. : )
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