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Old 12-28-2013, 07:37 PM   #1
Rethy OP
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Joined: Feb 2005
Location: Iowa
Oddometer: 100
Valve Clearance question

A couple questions for those in the know. Recently acquired an 07 990 with 16K miles. Valve clearance checks made. 3 intakes okay. 4th is on rear cylinder @ .178mm little loose but suspect okay. Exhaust rears are both at the minimum allowance .25mm. Best I can tell KTM recommends 9K clearance check intervals. So my question is if I should address the 2 exhausts even though they are in spec. (minimum spec). I will check them again in 9K miles. Is it common to have much movement in 9K miles? If not I will leave them alone. Also is there much benefit in removing secondary butterflies. Seems like KTM went thru a lot of expense to put these on. Must be some reason but not sure why they are even on there.
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Old 12-28-2013, 08:03 PM   #2
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There is a link in the 950 how that gives part numbers for harley v-rod shims, which work fine on the 990, and they come in half sizes, so you could add some clearance and keep it in spec.

I checked my valves at about 9, 16, and 24K miles and have had to shim each time. The last time was just the rear two exhaust valves and the others seemed to be holding. But anyway in my case they do seem to move a bit.
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Old 12-28-2013, 08:15 PM   #3
Jerkus Maximus
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Location: Lowville, NY
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Yeah, I'd open up the exhaust valves and get away from the minimum, but I wouldn't sweat the one loose intake. I'd bet in 9k miles they will be the same.

In my case, three LC8's and only one needed touch up on a couple valves, and even that was me being anal. I've found them remarkably stable.
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Old 12-29-2013, 02:52 PM   #4
Rethy OP
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Secondary butterflies

Thanks for the replies. I will go ahead and replace the rear cylinder exhaust shims. I will post my question on the secondary butterflies separately.
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Old 12-29-2013, 10:16 PM   #5
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Location: NorthWet Washington
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and to make things interesting....

I intentionally set my valves on the bottom (tight) of the spec cuz I want as much lift/duration as I can get.... but that is when I am planning on being 'near home'. If I was running off on a very long term ride, I would set them to the high side of the clearance just to get as much service life without having to peal it apart somewhere in the world to check/set.

I have found that these engines/valves are very stable and during intervals only change very slightly.
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Old 12-30-2013, 03:20 PM   #6
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You may find that by turning the shims upside down the clearances go back into spec, this is because the valve stem wears a hole into the shim, the bucket is far wider so the shim sits a fraction thicker.

The 250F is a bugger for doing this, the valve stems are smaller diameter than the LC8.
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