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2004 749S, 2006 MTS620
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30 Posts
Discussion Starter · #1 ·
Guys,

With the half-collet question answered earlier, I am starting a new thread regarding servicing the valves on my 2004 749S. I am the original owner of this bike and it has 6000 miles on the clock…and the valves have never been adjusted. It runs fine and I have had no issues whatsoever with it in any way. But…I want to learn how to service it myself and have run into a huge problem...the cams are stuck!

First, I had established the “base” position by rotating the crank until the layshaft timing dot was aligned with the mark on the clutch housing cover. I verified the horizontal cylinder was at TDC and placed marks on both horizontal and vertical cylinder cam wheels. I then rotated the crank 270 degree to bring the vertical cylinder to TDC and placed a second set of marks on its cam wheels to show where it was at TDC. I also marked this vertical TDC position on the layshaft, too. So…at this point I had “base” marks on the layshaft and both H/V cam wheels – and a second set of marks on the vertical cam wheels and layshaft in order to indicate TDC on the vertical cylinder.

The head covers were removed and I then very carefully measured the valve clearances with each cylinder at TDC. All of them were a bit “loose” but nothing was there to cause any worry.

After being absolutely certain of the opening/closing clearance values between each rocker arm and its camshaft lobe, I wrote all these down on my worksheet I then went back and re-measured everything again to make sure the values were the same. This was done on both the horizontal and vertical cylinders at their TDC…and the measurements all matched.

I removed all the opening/closing shims and very carefully measured each of them numerous times to make sure I had an accurate gage of their thickness. These values were all entered into the worksheet…and to be sure I re-measured each shim at least 5-6 times using the EMSDuc opening and closing shim tools.

After all the values were entered onto the worksheet, the figures came out to what was expected – since my opening/closing clearances had all been loose on every valve – I needed to replace all 16 shims. The goal I was looking to achieve was .005” clearance on the openers and .002” on the closers.

From there I obtained from EMSDuc the shims I needed to change and sanded some of them down to reach exactly what was needed for that specific situation. Many measurements were taken to make sure all 16 shims were exactly what I had calculated was necessary to achieve the correct clearances. Now that I had experience taking them out, getting all 16 shims back in was not too much of an issue and all the half-collets went into place. For each closing shim I made sure to snap its rocker arm several times to ensure the collets had seated properly. No problem there either.

As I had started with the vertical cylinder, I made sure the TDC marks on the layshaft and each cam wheel were properly lined up and then installed the vertical cams into place. I also made sure they went into the correct location and not accidentally installing the intake into the exhaust slot. Placing both hold-down clamps over the cams, I did the “first snug” torque to 7.5ft lbs and made sure all the vertical timing marks were still lined up…they were.

Getting a bit excited that things looked good for this first valve adjustment, I decided to check the clearances before doing the final tightening to 16.6ft lbs. Opening clearances were utterly dead on…all four valves were exactly .005” on the feeler gage – and that is when the problem started. Not a single closer had any clearance at all…no feeler gage could go through the gap between the cam and lobe as there was no gap!!!!!

The timing marks were still at TDC on the vertical cylinder…and when I gently tried to turn each cam by hand the exhaust would barely move and the intake would not turn at all. No matter what I did, the closing gap was totally at zero.

Several hours later after checking every single entry on the worksheet, they all still calculated to exactly what I had originally worked out. This has really stumped me as the cams easily rotated by hand (the intake cam was a little harder as it was under spring pressure) when I initially checked their clearances. Now, with all the new shims in and the openers being perfect…I am looking at locked up cams...with the closing shims being my chief suspect.

I have not gone to the horizontal cylinder yet as I absolutely want to sort out this issue with the vertical cylinder before going any further. Also, as the vertical cylinder is at TDC I am very aware how close the piston is to the valves.

What should I look into?

Thanks!!

Head Tomcat scratching his head
 

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you need to fit the tapered collets with the tool that pulls the shim over the collets tightened to a torque spec..
 

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2004 749S, 2006 MTS620
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30 Posts
Discussion Starter · #3 ·
That was it! I forgot I had the EMSDuc tool for this job and felt that snapping the rocker arm several times on the closing shim would be sufficient to load the collets...nope, it did not. Once I got out the tool and then torqued each closing shim to the correct specs, every single closer was good to go and I got the clearance I wanted on each of the eight valves.

That was exactly the advice I needed and thanks so much!

Head Tomcat who is feeling a lot better
 
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