748s valve clearance specs - Ducati.ms

Gforce · Jan 30th, 2006, 8:06 pm

I figured this has been beat to death but I've searched the archives and found no definate answer.
My haines manual and digital version of the factory repair manual do not agree. Why would an exhaust closer require the least clearance?

Is there anyone out there that has done there own valves numerous times on their 4v desmo, who rides hard (track maybe) and has had minimal rocker wear over thousands of miles, interested in laying their secret clearance specs on the line here.

I, for one, would be very greatful for your assistance in this matter. And, I know, these specs would only be a suggestion.

ducatimike · Jan 30th, 2006, 9:38 pm

I go with LT Snyders recommendations on my 916. I think its .10 mm for all closers and intake openers and .15 mm for the exhaust openers. I run my 916 exlusively on the track. I run it very hard. I have about 1800 track miles (7,800 total) on the bike. I installed the MBP collets at 6,000 miles. You may want to consider the MBP collets, especially on a 748 that revs higher. My bike is running very strong and may check the clearances before the track season starts this year if I have time.

The rocker wear can be due to out of tolerance clearances, but it also happens because the plating on the surface of the rockers on some bikes is crap. I had two opening rockers flake at the 6000 mile interval and the clearances were within spec when I checked them. I exchanged the two rockers for some reworked ones from Megacycle.

Concerning the clearance specs. The closers tend to open up a bit and the opener clearance tend to get smaller as the valves seat in and the half rings deform.

Mike

Gforce · Feb 3rd, 2006, 6:35 am

Thanks Mike,
I think the 916 runs them a CH tighter, do you think .13 would be a good setting?

ducatimike · Feb 3rd, 2006, 10:03 am

I dont have the LT Snyders book in front of me, cause I am in the middle of a move, but I think he recommends the same clearances for the 748 as for the 916, but I am not absolutely sure about that. I do know that what really hammers the half rings are too loose clearances for the closing rocker, especially in the 748 that is run hard like during a track day. I have contacted LT on occasion and his recommendations come after much direct experience. He has serviced many many Ducatis and so I have respect for what he says.

Mike

Gforce · Feb 3rd, 2006, 12:45 pm

I called BCM Ducati this morning and the Tech told me they use .1mm-.15mm for IO's, .15mm-.2mm for XO's, and .05mm-.127mm for all closers.
In inches it equates to .004-.006, .006-.008, and .002-.005 respectively.
Thanks for your input Mike, I apprerciate it.
Have a GREAT weekend.

OldBaldy · Feb 4th, 2006, 12:12 am

The Haynes manual is incorrect. Use the factory specs. The haynes specs are transposed.