Ducati.ms - The Ultimate Ducati Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
140 Posts
Discussion Starter #1
I'm putting my bike back together after removing the heads to do the valve clearance check. I have a question about putting the heads back on. In the engine torque settings it says to use Grease B (Molybdenum disulphide grease) on the bolts and on the head nuts to use Grease C (bearing/joint grease). Is this correct or am I reading the manual wrong?
 

·
Registered
Joined
·
2,434 Posts
I don't think it makes any difference. A bit of any grease should be fine to keep the threads from galling. It's a lot less work to adjust the valves without removing the heads :think:!
 

·
Registered
Joined
·
140 Posts
Discussion Starter #3
It's a lot less work to adjust the valves without removing the heads :think:!
I agree however being that this is the first time I have ever adjusted the valves I didn't realize that I had damaged the valve stem seals until after I adjusted every valve seal. The only way I was able to replace the seals was with the heads off.

Thanks for the reply.
 

·
Premium Member
Joined
·
2,482 Posts
I agree however being that this is the first time I have ever adjusted the valves I didn't realize that I had damaged the valve stem seals until after I adjusted every valve seal. The only way I was able to replace the seals was with the heads off.

Thanks for the reply.
Isn't it fun learning how to do stuff - as you do it? ;)
 

·
Premium Member
Joined
·
748 Posts
Does it make sense to replace the head studs while you've got them off on an 800SS? I know it's a no-brainer on a carbie SS if it had stock studs, but I'm curious if the stud issue was a problem on these later f.i. bikes. I, like many of us, have snapped head studs on our carbie bikes.
 

·
Registered
Joined
·
140 Posts
Discussion Starter #9
Did some surfing. I guess there are to ways. One is the regrind the seats and the other is to use a big clamp and press the valve into the seat. Is this the idea and which is the better (and cost effective way)?
 

·
Registered
Joined
·
823 Posts
Lapping the Valves
This entails smearing valve grinding paste onto the valve contact area, and manually spinning the valve with a suction cup type tool so that the valve seat and valve grind against each other and very lightly removes any imperfections from the contact surfaces between the valve seat and valve. You can buy the paste and suction cup tool from any auto parts store. The paste is available in course and fine grades. This is a very easy job, just don't get carried away and be sure to clean the valve seat and valve sealing face when your finished.
 

·
Registered
Joined
·
2,434 Posts
Lapping the Valves
This entails smearing valve grinding paste onto the valve contact area, and manually spinning the valve with a suction cup type tool so that the valve seat and valve grind against each other and very lightly removes any imperfections from the contact surfaces between the valve seat and valve. You can buy the paste and suction cup tool from any auto parts store. The paste is available in course and fine grades. This is a very easy job, just don't get carried away and be sure to clean the valve seat and valve sealing face when your finished.
What he said :), except that I held the valve stem with my fingers and didn't use a suction cup tool. Takes about 1 minute per valve.
 

·
Registered
Joined
·
140 Posts
Discussion Starter #12
Watched some videos, looks like it's beyond easy to do. One video had the valve attached to a drill spinning in one direction while popping every so often. Would you use the drill or stick to the suction cup?
 

·
A 748 Fanatic
Joined
·
3,155 Posts
Use caution and do it by hand. Lots of stuff gets ruined by power tools.

I'd use the suction cup stick. You can remove too much, way to quick using a power tool. You don't want to widen the contact area more the whats needed to accomplish total contact. Wider valve seating surfaces are not better.

My 2 cents
 

·
Registered
Joined
·
140 Posts
Discussion Starter #15
That's what I figured. One last thing. I used a nylon brush and seafoam to get the carbonization off. It left some visible scratches but nothing that you can feel, just visible. Since lapping the valves will fix the any on unevenness between the valves and the seats I am not worried about that however I did the same on the piston head and notice that same scratching on the cylinder walls. I was going to sand it a bit with a worn sheet of 600 grit to polish it (noticed the same effect on the valve shims, polished finish and no visible scratches) and then put some oil on the walls slowly move the piston up and down so the rings can adjust. Am I doing this the right way or just I not bother with this step?
 

·
Registered
Joined
·
2,434 Posts
This is not clear. Did you sand the cylinder walls? Don't. You are probably seeing the original cross hatching on them. A light touch with a ball hone is ok if you put in new rings, otherwise leave the cylinder walls alone. The top of the piston doesn't really need to be polished. It will get rough from accumulated carbon soon enough.
 

·
Registered
Joined
·
140 Posts
Discussion Starter #17
I used a nylon wheel brush on the end of a drill with seafoam to clean the heads and the pistons. I don't have a picture of the cylinder walls but I do have pictures of what the heads look like so you can get an idea of what the scratching looks like. I can get a picture of the cylinder walls tomorrow.



 

·
Premium Member
Joined
·
2,482 Posts
Hmmm. I don't know if that is actually going to cause any problems - but that IS the sort of scratching that supposed to be avoided on those areas.

Maybe use some fine (300-600 grit) wet and dry sandpaper to polish the scratches out. Or leave it. It should be OK - but anyone with more experience feel free to say otherwise...

FYI - The last engine I did a 'de-carb' on was a Mitsubishi V6 - I used aerosol 'Gasket Stripper' (and gloves - that stuff is nasty!) to clean up the top of the pistons and around the top of the cylinders. Talk about spray on - wipe off! No scraping needed - and that was on an engine with 130,000 miles on it.

 

Attachments

·
Registered
Joined
·
140 Posts
Discussion Starter #19
Thanks for the reply Steveb64. That's what I figured. Sand it down with some 600 grit sandpaper.. If there is a loss of compression I'll know right away at which point I can deal with it. I don't race so I am not to worried if there is a bit of compression gone. As long as I can ride till next winter at which point I can replace the rings.
 

·
Registered
Joined
·
140 Posts
Discussion Starter #20
I looked at some pictures and videos of cylinders after they have been honed. Looks like they have been scratched to hell. Apparently all the scratching makes the piston rings seal better. I have nothing anywhere close to that. I will have to take pictures later on today and post to show the minor scratching.
 
1 - 20 of 21 Posts
Top