What should my aural expectations be?

If it's broken or just needs tweaked

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nickjtc
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What should my aural expectations be?

Postby nickjtc » Sat Jul 29, 2006 4:23 pm

Just spent a pleasant couple of hours fettling the bike. If nothing else it is an absolute joy to be able to get at everything in a timely fashion! I used to have to strip off all kinds of fairing panels on the VFR800 I had, just to change the oil. And checking the valves on that bike........ don't ask!

The bike runs well and apart from taking a long time to warm it is doing exactly what I expect of it: it gets me to and from work on the 400+km each way trip I make once a week. It does not visibly burn oil, but I do have to put a cupful in every couple of weeks. I average 45 mp(imperial)g.

Anyway, here's the question. How mechanically noisy should the engine be?

No matter how often I check/adjust the valve clearances or adjust the camchain, or balance the carbs (did all that today) there is still a lot of (what appears to be) top end clatter. Whats most interesting is that the 'noise' is not consistent. It gets slightly quieter as the engine warms up, but not a lot. Sometimes it sounds like it is mainly coming from the centre of the top end (cam chain?) sometimes from an indeterminate location; could be any one of the tappets. Sometimes, especially as the motor warms up, there is a rumble from lower down.

I am not unduly perturbed since the bike has carried me close to 6,000 trouble free km since I got it two months ago. The problem is that there aren't any other sohc4's hereabouts, of any description, for me to listen to.

I'd be interested in your feedback.
.....to be myself, a pattern for others.

1979 CB650
1971 Norton Commando
1968 CB175

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DammitDan
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Postby DammitDan » Sat Jul 29, 2006 9:37 pm

Have you adjusted the cam chain? There's a nut on the back side of the cylinder block on the bottom in the middle... It's the nut that controls the adjuster for the cam chain slack. Loosen the nut, crank the engine by hand a few times, and tighten it back down as you crank (this is much easier with 2 people).

A loose cam chain will slap the adjustor as it rotates... Loosening the nut bows out the adjuster and takes up all the slack.

This engine should run like warm butter, with very few clicks or clanks.

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Ibsen
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Postby Ibsen » Sun Jul 30, 2006 12:43 am

Like Dan said, the cam chain will clatter if it isn't properly tensioned.

Another way to adjust it is by loosening the adjuster nut and crank the engine on the starter motor with the engine kill switch set to off. According to the workshop manual, the engine should be turned at least 5 full rounds. Sometimes you also have to loosen the the upper mounting bolt for the tensioner a little to make it work properly. You can also check if the camchain is loose or tight if you take off the middle valve adjustment cover. In front of the rocker cover, just above the camchain tunnel, there is a small hole where you can check the tension between the cam sprocket and the front cam chain guide by using a screwdriver and a flash light. The chain should not be dead tight, but it shouldn't be very loose either.

When started cold there will always be some mechanical clatter, but when fully warmed up it should runny pretty smooth. One small clatter that I have got in mine will not go away though. I have got some freeplay in the ignition timing advancer that is producing a small clatter at idle when the engine is warm. I have tried to regrease it, but it still isn't quiet. But as soon as the engine speed is increased and the springs are tensioned by the weights, it is quiet.

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nickjtc
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Location: Kamloops, BC, Canada

Noise

Postby nickjtc » Sun Jul 30, 2006 1:39 am

I always adjust the camchain per the Honda manual, which says to loosen the bolt, which supposedly does the necessary adjustment, then tighten it again, whilst rotating the motor using the bolt on the right hand tight of the motor. It never seems to make much difference to the overall top end noise. I'll try the electric starter procedure tomorrow.

Since I have no idea how many miles are under the wheels it could well be that the motor is just getting tired.... I haven't done a compression or leak down test yet to see how things are in the cylinders.
.....to be myself, a pattern for others.



1979 CB650

1971 Norton Commando

1968 CB175

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kc13661
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Same rattles

Postby kc13661 » Sun Jul 30, 2006 3:33 pm

I have exactly the same problem, At first it sounded like the cam tensioner then seemed to be deep in the bottom end, later moving towards the clutch area.... a travelling gremlin......I also have tried adjusting the tensioner by rotating the engine using the bolt on the right hand side method, this has had no affect but I willl try spinning the engine off the key, I have given up using the data in the Haynes workshop manual and now rely on the expertise of this forum. Obviously if you are covering that sort of milage with no problems then it sounds like a prettygood motor you got yourself.
Stay Safe Stay Upright

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nickjtc
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Location: Kamloops, BC, Canada

Noise

Postby nickjtc » Mon Jul 31, 2006 9:12 pm

Did a complete tuneup on Saturday. It seems to be running quieter. Maybe it's my imagination....
Last edited by nickjtc on Tue Aug 01, 2006 11:35 am, edited 1 time in total.
.....to be myself, a pattern for others.



1979 CB650

1971 Norton Commando

1968 CB175

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Volker_P
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Postby Volker_P » Tue Aug 01, 2006 1:44 am

There is some rumble from the cluth at low rpm when its cold. That's quite normal and may improve by carb syncronization somewhat but will not vanish completely. You can use a screwdriver on your ear like a stethoscope to localize the origin of the sound with some precision.
I also recommend to do the screwdriver check for the cam chain proposed by Ibsen. Then you know what you have, no trick or special adjustment method will help if your tensioner is stuck or your chain is lengthened.

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DammitDan
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Postby DammitDan » Mon Aug 07, 2006 12:37 am

I also found that on my bike the adjustor nut was bottoming out and not tightening the adjustor springs correctly. I went out and bought an open-ended nut and cranked her down... No more top end noise!

Guest

Postby Guest » Mon Aug 07, 2006 12:54 am

DammitDan wrote:I also found that on my bike the adjustor nut was bottoming out and not tightening the adjustor springs correctly. I went out and bought an open-ended nut and cranked her down... No more top end noise!


Now that is something worth looking into......

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Vatch
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Postby Vatch » Mon Aug 07, 2006 6:24 pm

I have a noise in the lower left side of the engine, below #1. I've adjusted the cam chain and the tappets, is this the location of the clutch noise when cold?
'99 1500 Drifter

Guest

Postby Guest » Mon Aug 07, 2006 9:55 pm

Vatch wrote:I have a noise in the lower left side of the engine, below #1. I've adjusted the cam chain and the tappets, is this the location of the clutch noise when cold?


I noticed that too with my bike, this weekend.

Anyone......?

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Ibsen
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Postby Ibsen » Tue Aug 08, 2006 2:34 am

What's located down on the left side, just below cyl #1 is the generator. Also the oil pump is located on the left side, inside the chain cover but outside the crankcase. The clutch is located on the right hand side, on the outside of the gear box.
If you let the engine idle to slow when it is cold, the primary drive in the middle of the engine, and the clutch will make some noise. I can't recall any noise from the left hand side on my engine. That doesn't mean it isn't any, it could be that I haven't noticed it.


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