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Author Topic: Strange rattle on de-acceleration  (Read 1057 times)

AussieDave

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Strange rattle on de-acceleration
« on: November 12, 2013, 06:29:03 AM »
Hi everyone. A couple of weeks ago I posted about I noise that I thought may have been a loose nut or something in the crank case. I looked behind both of the covers and did an oil change and ran it through a strainer but I didn't find anything. After the oil change the noise disappeared for a while untill I gave the bike a bit of a thrashing last week and now it's back. It is an intermittent rattle that happens with engine braking and sounds similar in tone to the noise made by the gear lever linkage . Like something is loose and kinda flicking about. Does anyone have a suggestion as to what could cause this? The motor itself is running fine.
"Glorious,stirring sight! The poetry of motion! The real way to travel! The only way to travel! ... O bliss ! O poop poop ! Oh my! Oh my!" - Toad of Toad Hall.

dampking

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Re: Strange rattle on de-acceleration
« Reply #1 on: November 12, 2013, 08:38:06 AM »
I had the same rattle on my AVL, in my case it was the primary side chain. Did you check your primary side?


High On Octane

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Re: Strange rattle on de-acceleration
« Reply #2 on: November 12, 2013, 01:34:38 PM »
More than likely 1 of 2 things.  Like dampking mentioned, it could be a loose primary chain adjustment or even a loose drive chain, but those tend to cause more of a "slapping" sound.  My guess is that your tappets are out of adjustment and beginning to develop too much play.  Normally when they are just starting to get loose they will act as you're describing, fairly quite upon acceleration but start chattering away the second you close the throttle.

Scottie
Bulldog Kustoms - Denver, CO
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The Blackhawk
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FULL RACE motor with ACE Performance

barenekd

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Re: Strange rattle on de-acceleration
« Reply #3 on: November 12, 2013, 05:47:35 PM »
My guess would be the primary chain or clutch.
Bare
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Royalista

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Re: Strange rattle on de-acceleration
« Reply #4 on: November 12, 2013, 07:07:04 PM »
You might also check your heatshield.
I went nearly berserk for over a month, searching for a similar sound, fearing the worst, as is common. Ultimately I found the slip that holds the front of the heatshield to the exhaust had broken off. That was the initial sound and after it fell off it was the front of the shield hitting the exhaust while revving and braking. Just a quick look.  :-\
moriunt omnes pauci vivunt

NorEaster

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Re: Strange rattle on de-acceleration
« Reply #5 on: November 12, 2013, 09:32:03 PM »
You might also check your heatshield.
I went nearly berserk for over a month, searching for a similar sound, fearing the worst, as is common. Ultimately I found the slip that holds the front of the heatshield to the exhaust had broken off. That was the initial sound and after it fell off it was the front of the shield hitting the exhaust while revving and braking. Just a quick look.  :-\

I had the same problem. Tab on the pipe did not mate with the slot on the heat shield. (brand new bike)
Took off the shield and tried to make it all fit better; but it still rattled. Took a small bit of exhaust wrap and folded it up between the heat shield and the pipe and clamped the two together with a stainless hose clamp.
Put the clamp in the depressed area of the shield under where the kickstart lever is.
No more rattles for me.

Arizoni

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Re: Strange rattle on de-acceleration
« Reply #6 on: November 12, 2013, 11:28:25 PM »
I doubt if it is the valve adjustment.  On the UCE bikes, there isn't any because the hydraulic valve lifters don't need it.

Has the rear chain been adjusted?  If it is too loose it can slap the rear swing arm.
Jim
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1999 Miata 10th Anniversary

AussieDave

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Re: Strange rattle on de-acceleration
« Reply #7 on: November 13, 2013, 02:57:49 AM »
Thanks for the responses guys. I have been right over the chassis and checked/ tightened up pretty much everything. I have the hitchcocks pipe and shield,which is solid. I checked the primary chain and it was taut with the auto - tensioner functioning as it should. I put a new tyre on last week( thanks Wildbill) and adjusted my chain- so no mystery noise there either. It's got me - expletive deleted- . I guess the rocker covers should be my next option.
"Glorious,stirring sight! The poetry of motion! The real way to travel! The only way to travel! ... O bliss ! O poop poop ! Oh my! Oh my!" - Toad of Toad Hall.

Craig McClure

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Re: Strange rattle on de-acceleration
« Reply #8 on: November 13, 2013, 04:04:41 AM »
I have known muffler baffles to rattle, & make you crazy trying to find the noise.
Best Wishes, Craig McClure

High On Octane

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Re: Strange rattle on de-acceleration
« Reply #9 on: November 13, 2013, 05:01:48 AM »
I doubt if it is the valve adjustment.  On the UCE bikes, there isn't any because the hydraulic valve lifters don't need it.

I'll admit I've never wrenched on a UCE but to the best of my knowledge just about every valve train has some kind of valve adjustment regardless if it's hydraulic, flat tappet or roller.

Scottie
Bulldog Kustoms - Denver, CO
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The Blackhawk
1958 Enfield/Indian 711cc Twin

Building the 1st EVER Supercharged RE Twin
FULL RACE motor with ACE Performance

barenekd

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Re: Strange rattle on de-acceleration
« Reply #10 on: November 13, 2013, 09:26:51 PM »
On Lycoming aircraft engines, the valve clearance is adjusted by different length pushrods. The range is something like .020-.080. This is how much the lifters need to pump up. But once they've pumped up there should be 0 clearance.
Bare
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Ducati Scotty

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Re: Strange rattle on de-acceleration
« Reply #11 on: November 13, 2013, 10:13:55 PM »
I believe most auto hydraulic lifters are adjusted once when they are installed, and that's it.  Not sure if they do or need to do that on our bikes.

Scott

Craig McClure

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Re: Strange rattle on de-acceleration
« Reply #12 on: November 13, 2013, 11:53:21 PM »
I do believe they are self adjusting pushrods. This was another selling point for me.
Best Wishes, Craig McClure

gashousegorilla

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Re: Strange rattle on de-acceleration
« Reply #13 on: November 14, 2013, 12:07:40 AM »
  No adjustment.  Like Bare describes above, it's spec'ed by rod length.  Which should put the rod down into the lifter, around the middle of the travel of the piston in the lifter.  When you go outside of stock spec's...... different valve train length or geometry, facing the head, gasket's, decking etc.  You may need different length, or adjustable rods.
« Last Edit: November 14, 2013, 03:41:07 PM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Arizoni

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Re: Strange rattle on de-acceleration
« Reply #14 on: November 14, 2013, 05:15:30 AM »
For what it's worth, the 500 UCE parts manual doesn't show any type of adjustment for the valve clearance.

It also does not show any other pushrods than the one intake length and one exhaust length.

Oddly, it does show two oversize cam bushings that are available in addition to the stock ones.  The use of these wouldn't have any effect on the camshaft to rocker arm distance though.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary