Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: El__burro on June 07, 2017, 12:45:28 PM
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I am not ready for bad news but..
Hopefully it wont require "gods hands"
Don't believe in miracles either.
What's this noise?
Rattling chains inside the engine..
Thanks a lot.
el__burro
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If it's definitely chains, it will be either the camchain, or the primary chains. Have you adjusted the camchain since the rebuild?
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No, I'm trying to get done right now. Looks simple..
Any help?
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It is as easy as it looks, I sometimes use a thin screwdriver poked in the back of the adjuster when the locknut and bolt are slackened to push the tensioner pushbar in just in case it has stuck. But do remove the screwdriver before tightening the lock bolt/nut, the idea is to let the spring pressure only hold the tensioner before tightening.
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First attempt.. failed
1 have cylinder 1 both valve closed at 15° past T.
2 Unlocked and released bolts from tensioner.
3 Re tightened and lock both bolts.
Turn on my not so "sawing machine" but still noisy.
Is this wrong or is the problem worse?
el__burro
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Try using a screwdriver or allen key in the back of the tensioner when the lockbolt/nut is slacked off, push until you can co no further, then remove screwdriver/allen key, then tighten lockbolt/nut. The reason for doing so is quite often the tensioner pshbar sticks in the casting, or the oil seal is an exceptionally tight fit, and it makes sure the pushbar can move and tension the chain.
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Done, I've used a plastic fisher to push in but cannot feel any movement.
Thinking of removing the
tensioner, should I?
Thanks
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By all means do, and with the lockbolt removed the pushbar should move freely, with spring pressure behind it. If it feels stiff (other than spring pressure) it will need investigating further.
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Here it is.
Any opinion on it?
It moves freely.
Thanks
(https://uploads.tapatalk-cdn.com/20170607/0508f27d693f87467c30697319ab408f.jpg)
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Difficult to say, I can't see it
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It looks normal to me.
If your carb synchronisation or timing is out, the rough running will cause noise from the cam and primary chains. Have you had this checked?
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Can see it now, yes it looks perfectly serviceable. Have you adjusted the tappets since having it running? And what sort of condition were the rubber wheels on the tensioner and guide in?
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Can see it now, yes it looks perfectly serviceable. Have you adjusted the tappets since having it running? And what sort of condition were the rubber wheels on the tensioner and guide in?
I'm not sure if i can check the rubber weels without opening the engine..
or can I?
Carbs sync done a while ago. Timing before that.
Do them both soon.
Thanks
el__burro
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I was talking about when the motor was apart. You can't see them when the motor is together. Have the tappets been checked/adjusted since getting on the road?
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Are you sure the sound your hearing isnt just the usual clutch rattle. They sound like a bag of spanners when ticking over. At tickover in neutral pull in the clutch and see if the sound gets less. If it's that you may be doing work for nothing, all the 750's have some degree of clutch rattle. Never did find a proper working solution for that.
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Here's the video. https://youtu.be/k0YJ_RJZyDo
Thanks
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By the sound of that the idle is low so it will rattle, you need to up the idle sync the carbs, set the valves and tensioner, you will probably then have a quieter machine that will probably have some primary chain and clutch basket rattle which will be normal.
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As Kevski has indicated, the idle that low will make a lot of noise anyway.
The primary drive chain, although tensioned, has no damper built into it so with idle below about 900rpm it'll just clatter the clutch and gearbox components, which is mainly what you hear.