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I'm doing my valves for the first time and getting all the measurements needed to order new shims. In doing this I found the exhaust valve opener clearance to be low (around .001"). I installed a new shim and re-measured, but I noticed that as the valve itself is rotated by taking off the opening shim and rotating the valve stem, the readings change. The opener clearance varied between .005" and .008" as the valve was rotated, but the closer clearance remained the same. What gives? Is the valve and or/seat out of round so I will need to remove the heads and lap it in?
 

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Put another opener shim in place of the present one and see if you still get the same results. If the clearance doesnt change then you know its the opener shim. If it still changes than it sounds like the end of the valve may be bent. I say this because you say the closer clearance doesnt change. So this tells me that the valve is straight at least up to the closer shim. If you have some thick feeler guages, you could just remove the shim and measure the clearance between the end of the valve stem and the opening rocker arm.

When you take the opening shim off and rotate the valve, can you see runout (the end will wobble as it is rotated) on the end of the valve stem?

Mike
 

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Thank you, those are good suggestions I will try them and get back to you. Is it possible that the valve is straight but the valve seating surface is uneven causing the difference as the valve is rotated? I measured the closing shim clearance through the opener shim loaded/unloaded method, but the difference between the two remained constant even as the opener clearance changed which I assume means the closer clearance is constant. Are bent valves something that is know to happen to these bikes? It would seem weird to me that the 8mm steel shaft is bent, especially just at the top section.
 

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The face of the valve may have debris on one side or on the seat. The closer will not change much because on a 4-valve the closers have clearance and it can be hard to detect a small amount of difference. If it was a 2-valve where we set the closer at zero you might detect a change.... might not also.

If you are worried I would check the leakdown on the cylinder and if the air is pouring out the valve in question something is up. I do see pits and debris on valves all the time and on a motor with high miles and has not been fogged much then it can be worse. If it is Minimal then it may be serviceable without burning a valve.

Like others have said before I went any further test the measurement with a known good shim/valve. measure a different valve and put that shim on the valve in question and see if the variance continues or put the shim from the odd valve on the good valve. It is not uncommon to find a shim/valve combination that does not work, this is where having more than one of each size comes in handy.
 

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Honestly I wouldn't sweat it too much. If the valve was bent, I would think it would damage the seal and you'd be burning oil. You're talking about 0.003 difference. Paper towel lint could cause it. Most likely it's non-uniformity in the valve seat causing it, which is why valves are lapped when installed. When I did mine, I noticed that rotating the cam while measuring the clearance I got about 0.002 difference through the low side of the lobe.

See if the same thing happens when you rotate the other valve stems.
 

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ajustment anomolies...

I'm sure you sorted it by now but having done dozens of adjustments allow me to add some light to the topic...1) before you place the cams on, allow the closure rocker to snap up to the shim...feel that the valve stem is nearly flush with the shim...2) wipe off the oil from the cam and where it sits in the head...3) make the lobes point up so you are taking measures consistently from the same point on the cam/rocker...4) press the cam down with a finger and try to fit a .10 feeler gauge into both open and closure gaps...if it fits in the gap make sure a .15 doesn't fit...and adjust accordingly....now that your measures have been made a worn closing shim can be slightly dished so if you measure the gap at .05 and after install of the next size its .03 that is likely why (don't sand it, your more likely to need to replace the valve before it goes anywhere near its 2nd tolerance limit)...in my experience as long as a feeler gauge fits easily you will be OK or simply put a new shim with the same size back in....having said that and you are sweating over the minutia of only a few millimeters after 18k miles your likely to be fine for the next 18...if not the engine will fault and you will be summoned to check them again anyway...
 

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I'm doing my valves for the first time and getting all the measurements needed to order new shims. In doing this I found the exhaust valve opener clearance to be low (around .001"). I installed a new shim and re-measured, but I noticed that as the valve itself is rotated by taking off the opening shim and rotating the valve stem, the readings change. The opener clearance varied between .005" and .008" as the valve was rotated, but the closer clearance remained the same. What gives? Is the valve and or/seat out of round so I will need to remove the heads and lap it in?

I need to do the valves I my Xdiavel Where do you get the new shims from? Nobody In Sydney exchanges or sells them. Do your know what size in mm the shims are? Do you have to remove the cams to change shims? And help is very much appreciated.
 
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