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Old 05-18-2013, 09:09 AM   #1
ciukes OP
ciukes
 
Joined: Apr 2011
Location: London, UK
Oddometer: 25
KTM 640 LC4 - Loud clicking noise when idle

Hi guys,

Can you help me to identify source of loud clicking noise I can hear when idle?
It goes away if I rev a bit and comes back when engine is back to idle.
It comes from exhaust valves area. Can it be automatic decompression ?

http://www.youtube.com/watch?v=yqmnOkkR4iE

Any idea? Is this something to worry about?

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ciukes screwed with this post 06-04-2013 at 01:27 PM
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Old 05-18-2013, 10:24 AM   #2
Idle
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Is there any metal on the oil screen or the magnet?

It sounds like the valve clearances are too large. If that's the case, the cam follower bearings (CFB's = rocker arm bearings) are suspect.

If you find either intake or exhaust clearances way too big, the valve cover needs to come off to check the CFB's.

When you pull the inspection caps, find TDC and wiggle the rockers up and down. Note how much if any movement there is, then kick the engine over 6-8 times or use the starter to turn it over.

Then find TDC again and do the wiggle test again. If it's different, even a tiny bit tighter or looser than before, the bearings are likely toast.
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Old 05-18-2013, 10:33 AM   #3
Seikkailu_R
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Too slow idle and automatic decompressor working?
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Old 05-18-2013, 11:02 AM   #4
Droptarotter
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It sounds like it is idling high enough to stop the auto decompressor noise.

Better check your valves and go from there!

If valves too loose.......you might have a rocker bearing going.

Idle nailed it!

Cheers
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Old 05-18-2013, 02:17 PM   #5
ciukes OP
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Joined: Apr 2011
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Thanks you all for the advice!

Quote:
Originally Posted by Idle View Post
Is there any metal on the oil screen or the magnet?
Yes, I found some small bits of metal on the magnet.

Quote:
Originally Posted by Idle View Post
It sounds like the valve clearances are too large. If that's the case, the cam follower bearings (CFB's = rocker arm bearings) are suspect.
I adjusted valves to the expected values.

Quote:
Originally Posted by Idle View Post
Then find TDC again and do the wiggle test again. If it's different, even a tiny bit tighter or looser than before, the bearings are likely toast.
Damn... looks like this is the case.
I know I should fix it ASAP but... how many more miles I can put on the bike before the engine will give up?

Considering I can do the fix, is it the part #12 on the diagram we're talking about (rocker bearing) ?
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ciukes screwed with this post 05-18-2013 at 02:40 PM
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Old 05-18-2013, 05:10 PM   #6
laramie LC4
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Quote:
Originally Posted by ciukes View Post
Damn... looks like this is the case.
I know I should fix it ASAP but... how many more miles I can put on the bike before the engine will give up?
depends, how much you like your bike?

get it fixed, don't ride it until you do.

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Old 05-18-2013, 09:22 PM   #7
bmwktmbill
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Don't try to ride it, you can do very expensive damage.
You will have to rebuild the waterpump at the same time most likely if it hasn't been done so prepare yourself for that too....

Think about what will happen if the bearing fails completely, think about metal in your oil and about your roller bearing crank.

Just saying.

You are paying, this is, the price of KTM 640 ownership.
bill
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Old 05-19-2013, 04:14 AM   #8
ciukes OP
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The story continues...

I removed the cylinder head top. Disassembled the rockers for inspection and found nothing alarming to my eye.
Rollers are tight, surface is even. Visual inspection proves they're not oval.
What do you guys think? Have I done all the checks to make sure rockers are in tip-top shape?

All things together before disassembly


Exhaust valves rocker


Intake valves rocker
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ciukes screwed with this post 05-19-2013 at 05:24 AM
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