Questions on Valve clearance checks (I searched the forum but didn't find my answer):
1) I saw for 2 valve bikes that closer measurement should be as close to zero as possible with no drag when measuring, does the apply to 4 Valve bikes as well ?
2) What gaskets are mandatory to replace when I de the valve check. & belt replacement ?
Hey Stray! Congrats on the bike man! That was also my first Duc, loved the 748. She definitely took some time to learn, she likes to be ridden a very particular way. I was coming from a CBR so the transition seemed pretty dramatic, but totally worth it. the 1.5yr I had with my 748 taught me so much about riding, I'll definitely have another Tam Gen Duc someday (hopefully soon!)
There are quite a few opinions/guidelines on valve clearance, if you dig too deep into it you'll walk away more confused than you did coming in. This is what I've learned and gone by-
You want the closing value to be at or nearest to 0. Imagine the way the valvetrain works, on the cam cycle that closes the valves, you want the valves as tight as they can mechanically be for all of the obvious technical benefits. That being said, my set of feeler gauges goes down to 0.02. When I was doing the valves on my 1098 this winter I spent time changing shims, measuring, changing shims, measuring until I had all of my closers less than 0.04. The bike ran noticeably better.
Now if you go to a Dealership, as long as the valve clearances are within spec, they wont touch the shims. Ducati claims for most road going bikes, this is the best practice for all parties involved. If you go to a race shop, they'll try to get the closers nearest 0.00 as they legitimately can. The race shops are fitting custom shims to achieve this as the "out of box" shims are, at times, mathematically impossible to use and achieve a perfect 0. All in all, it really comes down to your personal preference. I decided to go for the 0 because I haven't gone that route previously, had plenty of time and appreciated the challenge. You'll understand what I mean by challenge when you start doing the closers
The "perfect" clearance on the opener shims is 0.10 *iirc* (not 100% if that's different for the desmoquattro vs testastretta). I felt the openers were pretty easy to achieve 0.05 and was able to get all of my openers to 0.05, 0.06 or 0.07. They're also the easiest to change out and don't have any half rings/collets to mess with. Unfortunately, you still have to reseat the cams and torque the holders down to get check your values.
My openers were all within spec, there was no "reason" for me to change the shims other than my personal decision. My closers were mostly within spec save for maybe 3, again I took it upon myself to dig in and "have fun" with it. In my personal opinion, setting the closers nearest 0 as I could is what made the bike feel different. My openers were not that far away from 0.10 so in my mind I equated the fact that since the closing shims had more change in spec, that was the result of the bike running better. Did it make more power? No. Did it feel faster? Mehhh, maybe. BUT it DID idle better, feel smoother off idle, through the powerband and overall just felt better/smoother/right etc. My personal evaluation on the amount of time I spent vs the yield, I'd take the time to do it again for the "perfect" values. I enjoyed it, it broke up the mundane nights of the winter and I felt I accomplished something kinda cool.
For gaskets, get the valve cover gaskets and you should be good. Don't forget to add sealant in the areas around the cam holders the FSM calls for. I also did a coolant flush at this point as well as an oil change.