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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: BearTrap on October 31, 2020, 05:09:17 PM
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Excessive whining?
Over the past year my K75 has developed an excessive whine right about 4300 rpm. It is quite deafening even with full face helmet. I recently took a 220 mile ride through the Southern California Mountains and the sound completely wore me out. Sure I could wear ear plugs but, prefer not to wear them except for long trips on the highway. BTW, it only happens under load. I can’t replicate the sound in neutral.
Take a listen to the audio file. You can hear it right at the 22 second mark (4300 rpm in third gear). It happens in 4th and 5th as well. Excuse the scuffing sounds from the cell phone being inside my jacket pocket.
https://youtu.be/f8kmH4JM_wU
Is this normal? 1990 K75T 56k miles.
Thanks in advance.
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Your video isn't accessible to the general public, Bear Trap. Modify its accessibility so it can be seen by anybody.
When did you last change rear drive and transmission gear oil?
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Changed to public however it's audio only.
Changed tranny and final drive oil about 500 miles ago. Noise seems to come from the front of the bike (high pitch whine). Had the noise before gear oil change.
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Front of bike?
Cam chain???
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That's pretty good audio. i believe you when you indicate the sound wore you out. High frequency noise will do that. I wear reusable ear plugs whenever I ride. They allow me to hear unusual noise if it develops but damp the high frequency noise. It's a habit I developed while running chainsaws, splitters and skidsteer loaders, all of which do a lot of whining.
I hear a metallic whine but can't identify it. I'd check where Gryphon indicated. If you don't have a mechanic's stethoscope, take a screwdriver and place its blade on timing chain cover down toward the rotor end and its handle to your ear and get somebody to rev the engine. Although this noise is heard under load, you might hear the chain rubbing on the rotor seal bore, which would indicate a worn timing chain tensioner and maybe a worn chain, too. You could remove the cover then look at the rotor seal bore on its reverse side for dings or gouges.
Any leaks at the combo pump weep hole? Take a listen there too.
Your moto had 50,000 miles on it in 2017. You adjusted the valves back then. How many miles does it have on it now? Others here will have more observations to add.
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I agree with you both. China Freight is just down the street where I can pick up a cheep stethoscope and listen for any abnormalities from the cam chain or the combo pump. I'll keep you informed of my findings. Cheers.
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If the noise started since doing the valves, I would suspect that the cam chain may have been disturbed while manually turning the cams. Curiosity would lead me to pull the timing chain cover from the front of the engine and take a good look at the tensioner and the chain guides.
At 56,000 miles, I wouldn't expect the chain to be stretched, but it won't hurt to take it off and check it for sideways bend. A good chain will be fairly stiff when you try to bend it side to side.
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Thanks again guys. I took some time to take a photo underneath and uploaded audio (with a stethoscope) of the cam chain cover and the oil/water pump.
The photo shows some weeping of coolant but not dripping. Audio of the cam chain cover sounds normal to me. However the oil/water pump sounds noisy with a similar sound that I’m experiencing. Maybe I should start with the pump first.
Cam chain: https://youtu.be/miEH3o9MkYA
Pump: https://youtu.be/aaeldkj0n6s
Can't upload the photo, says invalid attachment?
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Can't upload the photo, says invalid attachment?
The photo won't show in Preview but should show when posted regardless of that text. Try again.
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[ Invalid Attachment ]
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Over here my bike was idle for a few months when bikes were banned cause of the virus (I know, that's dumb) I'll guess there were 5 or 10 drops of coolant on the concrete floor under the pump when I started riding again. It wasn't leaking before or since, so I'm not worried about it.
The extra noise at 22 seconds, to me it's as quiet as an angels fart.
Sometimes putting a cap full of cutting oil in the coolant fixes a noise like that (it's very faint to me but I have ringing in my ears) I'm talking a gallon container cap, hopefully same there, maybe like a whiskey shot glass. The seal can get dry. Oil can sometimes get through small gaps that water can't.
Believe it or not.
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The bottom of your engine is too damn clean.
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:laughing1:
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I hear the same metallic rattle or buzz in both sound files. Is that your concern?
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The sound file is not that great. but there is definitely some chirping going on in the water pump. Maybe at higher speed that oscillates to a high pitch noise that I here while riding.
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Do both sound files sound normal to you guys?
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I hear the chirping just, I imagine it's louder in real life.
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There are several instructional sources for pump disassembly and inspection here and on the Web. You should review them. Patience during reassembly is critical. There is hardly any evidence of coolant or oil leakage in your photos. If you're convinced that the sound isn't coming from the timing chain case or somewhere else, my default choice would be wearing the most comfortable earplugs I could find then disassembling and inspecting the pump when leakage is greater than it is now.
When was the last time you flushed the engine and changed coolant?
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Good advise on the ear plugs. I flushed the coolant 4,705 miles ago early this year. I'll keep an eye/ear on the pump. If it doesn't get worse then I won't worry about it. Thanks for all the feedback guys.
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You changed the coolant early this year and the noise has developed this year, that's a hint that cutting oil might do the trick.
Oils ain't oils, you can get cutting oils that can be mixed with water.
If you gotts some, it won't cost you none.
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Thanks, I'll look into that.