Author Topic: Rattle  (Read 5216 times)

Offline Joolstacho

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Re: Rattle
« Reply #15 on: 22.08. 2018 00:54 »
I'm a little vague on this (well it is over 35 years ago!), but early in the life of my SR I had been sold a camshaft that had been re-profiled - by a well respected specialist camshaft firm I might add.
Enough material had been removed from the lobes that the cam followers were rattling bottoming out on the little screws at the base of the barrel when the cams were 'closed', instead of following the cams all around. It sounded like 'orrible piston slap. (It's possible that I had the follower faces themselves ground a bit as well). Cobwebs in my brain are mitigating against clarity here, someone may shed light.

Online duTch

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Re: Rattle
« Reply #16 on: 22.08. 2018 02:42 »

 Yes- one of the Kiwis, maybe RR (?) put this idea out there a while ago, but as GB has me cam and lifters is probably unlikely but not impossible.
 In fact, because I  had just finished rebuilding mine when I read it, I'm not sure if I addressed that factor,  having also a reprofiled cam, but not sure about the lifters.... *conf*
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 muskrat

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Re: Rattle
« Reply #17 on: 22.08. 2018 04:13 »
G'day GB.
Wondering if the lash caps have changed the geometry and a pushrod it rubbing on the head gasket. I've seen that happen and took a while to find it.
Cheers
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Online Greybeard

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Re: Rattle
« Reply #18 on: 22.08. 2018 08:41 »
G'day GB.
Wondering if the lash caps have changed the geometry and a pushrod it rubbing on the head gasket. I've seen that happen and took a while to find it.
Cheers

Mm, that's an interesting thought.

Online Greybeard

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Re: Rattle
« Reply #19 on: 22.08. 2018 08:53 »
I'm a little vague on this (well it is over 35 years ago!), but early in the life of my SR I had been sold a camshaft that had been re-profiled - by a well respected specialist camshaft firm I might add.
Enough material had been removed from the lobes that the cam followers were rattling bottoming out on the little screws at the base of the barrel when the cams were 'closed', instead of following the cams all around. It sounded like 'orrible piston slap. (It's possible that I had the follower faces themselves ground a bit as well). Cobwebs in my brain are mitigating against clarity here, someone may shed light.
I've recently changed to a new cam and followers. The previous cam was a reprofiled one.

Offline Joolstacho

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Re: Rattle
« Reply #20 on: 22.08. 2018 09:03 »

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Re: Rattle
« Reply #21 on: 23.08. 2018 15:54 »
When I was working on the bike t'other day I removed the sump plate to check for shrapnel. There was nothing nasty in the sump or screen. Also, only about a 1/4 pint of oil was in there, so I'm thinking that the ball check valve, (that I recently replaced) is doing its job.

duTch, the B31 lash caps that I fitted to my A10 Inlet valves do not go right down onto the valve collets. You raised a concern about them.

Online duTch

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Re: Rattle
« Reply #22 on: 23.08. 2018 22:04 »

 
Quote
.....duTch, the B31 lash caps that I fitted to my A10 Inlet valves do not go right down onto the valve collets. You raised a concern about them...

 Thanks, I'd forgotten about that (too)- don't suppose you made a note of the depth of the cups ?... *whistle*
 I think if anything, my pushrods are a tad short and don't think caps would change anything...
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
Australia

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Re: Rattle
« Reply #23 on: 23.08. 2018 22:24 »
I did not measure the caps, soz.

Offline edboy

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Re: Rattle
« Reply #24 on: 24.08. 2018 19:42 »
lash caps will be noisier but keep the gaps to factory settings and they will stay in spec longer. i.e. no need to increase gaps for longer adjustment intervals. also i believe they should be fitted with oil , not dry.

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Re: Rattle
« Reply #25 on: 10.09. 2018 12:24 »
Today I made a couple of vids to compare engine noise, cold and then hot

https://youtu.be/V5shdqTBaQg

https://youtu.be/KKyXTq8DEIY

What do you guys think about that rattle? I was hoping for a quieter engine following the work I've recently done.

Offline muskrat

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Re: Rattle
« Reply #26 on: 10.09. 2018 12:36 »
G'day GB.
Don't like the sound of that. Can you pin point a location of the noise with a stethoscope?
My 1st guess is a loose valve guide
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Online RichardL

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Re: Rattle
« Reply #27 on: 10.09. 2018 12:40 »
Muskrat,

Are you saying it's the sound of the valve guide slapping up and down while stuck to the valve stem?

Richard L.
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Re: Rattle
« Reply #28 on: 10.09. 2018 12:53 »
G'day GB.
Don't like the sound of that. Can you pin point a location of the noise with a stethoscope?
My 1st guess is a loose valve guide
Cheers

Thanks for answering this when it must be past your beddy-byes!

I don't have an actual stethoscope. I'll try with a stick.

Offline RDfella

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Re: Rattle
« Reply #29 on: 10.09. 2018 13:18 »
Listening to both I really can't hear anything amis above the exhaust apart from a faint irregular tick of some type. Primary chain? As for valve clearance, I wouldn't go below published figures on an iron head, because clearances close up when hot. They do the opposite on alloy barrels / heads. As for camshaft, was going to ask whether the profile had quieting ramps (not usual on motorcycles) and maybe the new cam was more aggressive without ramps, but then I don't think it's the cam making the noise..
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.