Author Topic: Tappets playing maracas?  (Read 2296 times)

Offline East_Coast_BSA

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Re: Tappets playing maracas?
« Reply #15 on: 24.06. 2015 20:24 »
At those speeds, how sure of you where the noise is originating from?  Do you think it's coming from the rocker box area or somewhere in the bottom end?  You also have to remember that all the drive gears are straight cut, not helical.  They are anything but quiet.  Maybe you're getting some "Backlash" in the gear train due to harmonics?  Is the noise consistent throughout the RPM range or is it louder at some points?  Accelerating, decelerating, steady state?  It's really a tough game when your engine isn't silent when it's running correct.  There always seems to be some noises going on.  Just makes things more difficult to find.

Offline RichardL

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Re: Tappets playing maracas?
« Reply #16 on: 24.06. 2015 20:42 »
Otto,

I don't recall piston slap coming into the conversation. During my last top-end work I ended up overhoning by at least two thou past book recommendations of "rebore cyclinders and replace pistons." I replaced the rings and all seems pretty good. No particular obvious slapping, so, if slap was the problem on your bike one might have to assume radical overhoning. Personally I don't think that's it. Right now, if it is actually a problem noise and not a usual noise, my bet is on rocker clearance adjustment being accidentally too big. In any case, at least that's easy to check.

Richard L.

Offline duTch

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Re: Tappets playing maracas?
« Reply #17 on: 24.06. 2015 22:25 »
 I don't recall piston slap mentioned either until now. ... But I just had a thought that I've had a noise the past few weeks that I've been attributing to primary chain, but my dynamo belt flogged itself last weekend..... So you have a belt or a chain...?
  Someone (jachenbach?), had that issue recently
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Offline roadrocket

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Re: Tappets playing maracas?
« Reply #18 on: 25.06. 2015 08:40 »
I read some of the remarks on different expansion rates as a hint to piston slap, I was obviously wrong there. So much for the better. The noise mostly occurs at 40-50 mph, and I rarely go faster than 65, however, I did do a stint on the motorway, and didn't pay any attention to noises there. All went fine at 75-80. My dynamo drive is SRM belt. I will try to make a video to record noises. The one I am worried about should maybe be described as a bit like a cicada living somewhere near the right hand side top end.
Otto in Denmark

Offline duTch

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Re: Tappets playing maracas?
« Reply #19 on: 25.06. 2015 08:43 »

 Chronic Tinnitus...?
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online KiwiGF

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Re: Tappets playing maracas?
« Reply #20 on: 25.06. 2015 11:30 »
Long shot but could you have duff push rods? There were definitely some duff ally rods in the marketplace for quite a while which had an incorrect radius on the ends causing the rods to stick in the cups and rattle......
New Zealand

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Offline roadrocket

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Re: Tappets playing maracas?
« Reply #21 on: 25.06. 2015 11:34 »
I'll check the tappet clearances again, and try to check the rods also.
Otto in Denmark

Offline East_Coast_BSA

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Re: Tappets playing maracas?
« Reply #22 on: 25.06. 2015 12:10 »
The one I am worried about should maybe be described as a bit like a cicada living somewhere near the right hand side top end.

The cicada noise mine was making turned out to be a head gasket.

Offline Butch (cb)

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Re: Tappets playing maracas?
« Reply #23 on: 25.06. 2015 12:23 »
The one I am worried about should maybe be described as a bit like a cicada living somewhere near the right hand side top end.

The cicada noise mine was making turned out to be a head gasket.

Ah yes, I've had that on mine. Used to chirrup under load only. Initially only under heavy load but then became more prevalent as the gasket further deteriorated.
Warning - observations made by this member have a 93% unreliability rating.

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'58 S/Arm Iron Head Flash Bitza


Offline a101960

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Re: Tappets playing maracas?
« Reply #24 on: 25.06. 2015 13:16 »
Same here. No visible sign of anything wrong either. In my case the gasket had failed between the cylinders, and has been said, initially it started when the engine was under load. It then progressed to happening every time I opened the throttle especially on a gradient.
John

Offline RichardL

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Re: Tappets playing maracas?
« Reply #25 on: 25.06. 2015 13:34 »
So, compression test.

Offline roadrocket

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Re: Tappets playing maracas?
« Reply #26 on: 25.06. 2015 16:03 »
Head gasket! That sounds very plausible, thanks for that! Any point in trying to retorque the head?
Otto in Denmark

Offline RichardL

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Re: Tappets playing maracas?
« Reply #27 on: 25.06. 2015 16:13 »
Compression test first, I believe. You wouldn't want to take off the rocker box just to tighten the head bolts only to discover that was not the cause.

Richard L.

Offline roadrocket

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Re: Tappets playing maracas?
« Reply #28 on: 27.06. 2015 13:23 »
OK, a compression test showed 150 psi in both cylinders. But that does not rule out a clattering head gasket I believe?
Otto in Denmark

Offline RichardL

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Re: Tappets playing maracas?
« Reply #29 on: 27.06. 2015 14:45 »
Others may know better, but I think that pretty much rules out the head gasket.

Richard L.