Replacing 796 Valve Seals

Can't help you on the stem seals as I do not know which type they are, but they are going to be either a nitrile or rubber variety which needs to be lubricated before fitment though. Avoid any sharp tools while fitting in case you score the seals.
Also worth checking your valve end play before you lap your valves in to see that the seals will work and not allow oil to pass between the seal and guide.

 

have you ever fitted any oil seals, particularly small ones? There will be an official Ducati tool of course but what you need is a short length of steel or preferably aluminium tube with an I/Dia that just clears the steel wound restrainer 'O' ring and outer dia the same or slightly larger than the seal O/D. The end you use needs to be deburred thoroughly as Peter said and even a small internal chamfer is a good idea. Some go on fairly easily but some do need some firm tapping into place. You could get a very long bolt* and nut of course and carefully draw it into position but you only need to use this method if the interference fit is high (and it shouldn't be anyway). You could try and start them off by hand to get an idea of how much force you will need. If you are at all worried that you can't insert them perpendicularly then use the 'drawing' method (and only a short piece of tube is then needed)

*should be plain, smooth shank touching inside of guide

 

I used this method on my 916, after having previously replaced them (obviously not well enough as two came off!) by drifting them on.

Used a 6mm bolt with a couple of modified (ground to fit in the head) large washers and a nut to pull them on gradually, pictures speak louder than words;













As for removing the old ones (those that hadn't come off and been mashed up by the rockers) a sturdy pair of bent-nosed needle pliers was just the job.

 

If you have even an average degree of mechanical aptitude, both removal of old and replacing with new really is a piece of Madeira..

 

I only used 2 washers to get the right thickness so that the 6mm washer above wasn't cutting into the rubber top of the seal, the big washer sat nicely onto the metal collar and I ground the side off so that it would fit inside the head. You may need to do it slightly differently to suit the seals and head on yours, I'm not sure what a 796 head is like and you may need different sized bolts/washers etc. (smaller valve stems?).

The important thing is to get it to seat straight, I think that my previous attempt (with hammer & socket as a drift) may have distorted the seals so that they weren't tight enough, so much so that 2 lifted off and were mashed by the rockers - when I did an oil change I found loads of bits of orange rubber, metal collar bits along with the obligatory gear chips and chrome flakes...