Author Topic: CB750 K4 whine  (Read 744 times)

Offline willythepooh

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CB750 K4 whine
« on: August 18, 2018, 11:50:39 AM »
As the title says, my K4 whines under load and slowing down. What’s the cause because it doesn’t seem to affect anything ?

Offline hairygit

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Re: CB750 K4 whine
« Reply #1 on: August 18, 2018, 02:33:19 PM »
If it's something you have noticed getting worse, then possibly gearbox bearings. If you only just got the bike, and are used to modern stuff, they do whine a bit, often can be heard over the exhaust sound, but that really is normal for straight cut gears (remember how much the proper Mini, not the crap bmw new ones used to whine?) 
If it's got tits or wheels, it's hassle, if it's got both, RUN!!!

Offline willythepooh

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Re: CB750 K4 whine
« Reply #2 on: August 18, 2018, 03:23:44 PM »
It’s never really got worse. Always been there. Just wondered if other bikes did the same.

Offline hairygit

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Re: CB750 K4 whine
« Reply #3 on: August 18, 2018, 05:14:48 PM »
If the exhausts on your bike are original, by 1974 the yanks were really clamping down on noise and emissions, so your silencers will be very effective, and yes, they all do it, it's just with noisier pipes it's harder to hear, and the whine always loudest in 3rd gear!
If it's got tits or wheels, it's hassle, if it's got both, RUN!!!

Offline Simon46

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Re: CB750 K4 whine
« Reply #4 on: August 19, 2018, 11:27:09 AM »
I wondered if the whine was normal too. Definitely let's you know you're in third!
1978 Cb750k8 US Import

Offline kevin 755

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Re: CB750 K4 whine
« Reply #5 on: August 20, 2018, 10:47:35 AM »
+1 Third gear whine.

Offline Simon46

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Re: CB750 K4 whine
« Reply #6 on: August 20, 2018, 11:17:02 AM »
Stop with the whining now  ;D
1978 Cb750k8 US Import

Offline paul G

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Re: CB750 K4 whine
« Reply #7 on: August 20, 2018, 12:08:07 PM »
Honda CB400 4
Honda CB550 K3 (sold)
Honda CB750 UK K1
Kawasaki Z650 C2
Kawasaki Z650 cafe racer (Sold)
Honda CD175 sloper

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: CB750 K4 whine
« Reply #8 on: August 20, 2018, 12:13:44 PM »
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LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Laverda Dave

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Re: CB750 K4 whine
« Reply #9 on: August 20, 2018, 12:50:24 PM »
My CB250RSA developed a horrendous and sudden whine although I think the noise came from the owner when it holed the piston.... £££££££'s :o
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

 

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