> You should never stone down the shims to size. That weakens the > surface hardening. A new shim of the correct size or a well used > but not worn out shim is greatly preferable.
Preferable but not always possible, original factory shims are perfectly OK after a light stoning, I'm talking very small increments. > And you should aim > for .001" clearance on the closers when making an adjustment, > not zero clearance. Closers are tolerant of up to .005-.006". Hence I state "0" clearence, basically never done by measurement, the closing shim should move with firm pressure of finger and thumb throughout it's base circle. Closing rockers may be tolerant of up to .005-.006" on a road bike because of "helper springs" aiding compression at low rpm but try telling Steve Wynne that when he and Roy Armstrong were preparing race engines. > More important than that is to rotate the cam through an entire > revolution with both valves installed to be sure there is no > binding anywhere, and check the keeper collets whenever you're > doing an adjustment to be sure they're not battered up too > badly. Yes absolutely and make sure that cam bearing end block is installed correctly when you check. I've been doing this for 27 years now :) John ---------- Original Message ----------- From: Godfrey DiGiorgi <[EMAIL PROTECTED]> To: pentax-discuss@pdml.net Sent: Tue, 22 Feb 2005 00:30:10 -0800 (PST) Subject: Re: A vision of Guzzis (OT) > John Whittingham <[EMAIL PROTECTED]>: > > I know from personal experience getting "0" > > clearence on the Desmo closing rockers can be time consuming > when you > > have to stone the shims down on the wet stone, having said > that they're > > likely to last 20-30,000 miles when done right. > > Unfortunately, this is typical Ducati lore due to the scanty > information provided in the manuals and aftermarket workshop > books. > > You should never stone down the shims to size. That weakens the > surface hardening. A new shim of the correct size or a well used > but not worn out shim is greatly preferable. And you should aim > for .001" clearance on the closers when making an adjustment, > not zero clearance. Closers are tolerant of up to .005-.006". > > More important than that is to rotate the cam through an entire > revolution with both valves installed to be sure there is no > binding anywhere, and check the keeper collets whenever you're > doing an adjustment to be sure they're not battered up too > badly. > > I've written many articles on Ducati maintenance over the past > 15 years. Most people follow the improper procedures because the > factory never really articulated setting the valves outside of > the factory technician workshop. > > Godfrey > > > __________________________________ > Do you Yahoo!? > Meet the all-new My Yahoo! - Try it today! > http://my.yahoo.com ------- End of Original Message -------
