Author Topic: Bad engine noise from C5  (Read 9900 times)

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Arizoni

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Reply #30 on: November 30, 2013, 01:17:37 am
It doesn't sound "clackity" enough to be the decompression device.  At least on the few times my G5 had the auto-decompression thing stick on very cold mornings it went clack, clack, clack, at  half engine speed.  It also quit if I revved the engine up just a little and once it was gone, it didn't return.

I hear a number of different sounds and I'm sure the mike is being moved around to different  places.
I hear the tickity tickity of the valves, the thump thump of the exhaust and occassionally a hollow thunking sound that sounds like piston slap.  I think I read the bike had been ridden before these recordings were made so the piston should have expanded making the piston slap guess unlikely.

Because there are so many different tappity, clickity, thumpity's going on, it sounds like a case for the Hose-ear.
I know you old timers already know this but, if one takes a short length of garden hose and holds one end to their ear, they can move the other end around to various strategic places to get a better definition of where the noise is coming from.

Sounds from the rocker arm areas would be valve clearance, sounds from the cylinder (front and back) might be a loose piston, clunking sounds from lower down on the crankcase may be bad bearings, whirring sounds from the crankcase are roller or ball bearings...etc....etc
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary


gashousegorilla

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Reply #31 on: November 30, 2013, 03:43:03 am
  Enough to drive a man CrAzY listening to a recording, without seeing it,  touching it, and hearing it all at once.... Riding it !   A owner knows his bike , and knows when it's right, or when it's not.........
« Last Edit: November 30, 2013, 03:56:08 am by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.


GreenMachine

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Reply #32 on: November 30, 2013, 03:27:09 pm
+1  and I don't own a domestic 350cc UCE either so I can only add to the confusion...
Oh Magoo you done it again


singhg5

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Reply #33 on: December 02, 2013, 04:28:33 pm
My G5 is also developing similar bad engine noise, more pronounced than C5 of ironhead.

The sound is less when engine is cold and oil is thick, but more when the engine is hot after riding several miles as in the link below -

https://www.youtube.com/watch?v=BdAGt_s07XA
« Last Edit: December 02, 2013, 04:35:05 pm by singhg5 »
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gashousegorilla

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Reply #34 on: December 02, 2013, 04:50:00 pm
 Rattle and tick..... Rev it Singh.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.


Royalista

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Reply #35 on: December 02, 2013, 07:34:20 pm
Contagious? It must be the plague...  :o

Bring out your dead...
...Pie Jesu Domine, dona nobis pacem
(Monty Python & The Holy Grail)

By the way, last week I made a video because I had installed a new mount for the camera. All's well until I played the video at home. Probably under the influence of this thread I started to worry about the engine noise. The mic of a camera is but the mic of a camera.

Sorry, I remain a non-believer.  ;)
moriunt omnes pauci vivunt


singhg5

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Reply #36 on: December 02, 2013, 09:35:24 pm
Rattle and tick..... Rev it Singh.

Between 28 to 50 seconds of video, I hear a resonating tuning fork sound as if a hollow bell was getting struck repeatedly.
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GreenMachine

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Reply #37 on: December 02, 2013, 09:50:08 pm
Actually that sounds pretty good compared to Ironhead ;)
Oh Magoo you done it again


gashousegorilla

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Reply #38 on: December 02, 2013, 10:22:20 pm
My G5 is also developing similar bad engine noise, more pronounced than C5 of ironhead.

The sound is less when engine is cold and oil is thick, but more when the engine is hot after riding several miles as in the link below -

https://www.youtube.com/watch?v=BdAGt_s07XA


 
Between 28 to 50 seconds of video, I hear a resonating tuning fork sound as if a hollow bell was getting struck repeatedly.



  Yeah, I hear that little bit of ringing now Singh.  Thats not your rear head steady mount, or your pipe is it ?  This is a new  sound, and you didn't hear it in the summer when the oil would thin out quicker?.....   Using thinner oil for the winter ?
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.


singhg5

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Reply #39 on: December 03, 2013, 04:58:22 pm

 

  Yeah, I hear that little bit of ringing now Singh.  Thats not your rear head steady mount, or your pipe is it ?  This is a new  sound, and you didn't hear it in the summer when the oil would thin out quicker?.....   Using thinner oil for the winter ?

Same oil as in summer. There was no sound in summer. Pipe and head mount seem OK. 

Tried to use a tube to hear running engine. I put one end of a rolled up large paper into a tube to my ear and other end to different parts of engine. No doubt the sound was louder (all sounds magnify) with this 'stethoscope'. A baseline sound is needed to compare the 'before' and 'after'.

The closest recording of 'before' is in the link below, which has music but engine sound is clear between 0:35 to 1:35.

http://www.youtube.com/watch?v=HV_K5O25w6A
« Last Edit: December 03, 2013, 05:00:49 pm by singhg5 »
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ace.cafe

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Reply #40 on: December 03, 2013, 05:16:35 pm
FWIW, it sounds to me like a piston slapping at idle.
How many miles on the engine?
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singhg5

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Reply #41 on: December 03, 2013, 06:35:24 pm
FWIW, it sounds to me like a piston slapping at idle.
How many miles on the engine?

About 30,000 miles.

A little background - On a cold morning when I had started the engine, it was barely thumping, seemed like it was about to quit. I was a couple of feet away from bike. I rushed to throttle and abruptly opened it to give more gas, but the engine stalled. The sound started after that. At that time it seemed the sprag had broken with a 'CLUNK'.  I took out the sprag clutch and now have a new one in the engine. But the sound is there which was not there before.
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gashousegorilla

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Reply #42 on: December 03, 2013, 06:53:42 pm
  Singh, you could try a compression test.  Do it using the starter, with a fully charged battery....hopefully the auto decomp won't skew the readings this way.  Disconnect the fuel pump and throttle wide open when you do it..... see what you get.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.


ace.cafe

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Reply #43 on: December 03, 2013, 06:57:28 pm
I would say ride it over to Chumma, and let him check it out, and see what he can do for you.
Home of the Fireball 535 !


Ducati Scotty

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Reply #44 on: December 03, 2013, 07:14:55 pm
  Singh, you could try a compression test.  Do it using the starter, with a fully charged battery....hopefully the auto decomp won't skew the readings this way.  Disconnect the fuel pump and throttle wide open when you do it..... see what you get.

Yes, make sure you hold the throttle wide open while doing it.  I always forget that part and wonder why my reading is so low.  The manual says something like 110psi as the spec but I've found my bike reads consistently around 130psi with the electric start.  I suspect the lower reading might be if you're using the kick start for the test.

Scott