Last night I had to do it out. I fiddled with the carbs, the jetting, the ignition, the valve clearance on the SS for a total of around 50 hours. At my “cheap” consulting rate of 40$/hr (before) taxes, that means I spent the equivlent of 2,000$ trying to get my ‘95 Ducati SuperSport to run right.
Last night, with the help of Zsolt and Cyndi, I pulled the motor out of the frame yet again, and tore into the ailing vertical cylinder. Just looking at the valves, I could tell something wasn’t right. I did the solvent test in the combustion chamber with both valves closed at TDC, and sure enough, the liquid disappeared behind the exhaust valve. Took the valve out, lapped it quickly and noticed that it wasn’t lapping very easily. A pretty decent ridge of carbon buildup right above the face of the valve wasn’t allowing it to seat fully. I sprayed some aircraft-grade aluminum stripper and let it soak. As of 10:30pm last night, I was still fighting trying to remove the carbon ridge from the face. But I’ll get it. I’m concerned about ruining the face of the valve with anything real tough, so I think I’ll just spend some time with a scotch-brite pad, and some fine grit sandpaper to try and remove the carbon. I’m open to suggestions though (except buying new valves).
Its very frustrating to spend that much time for a simple, stupid problem like this. On the plus side, the bike should purr like a kitten now that both valves are seating correctly. Completely explains the running issues I was experiencing.
All this makes me like the Moster that much more. I can pull cylinder heads and jugs off without removing the motor from the frame. I’m either going to have serious back problems, or some serious muscles for the number of times I’ve wrestled this aging Italian powerplant in and out of its trellis frame.
UPDATE: I thought that the carbon ridge was what was preventing the valve from lapping correctly. Rocky saw my picture and with a good eye said “That valve looks bent!” I initially thought he was just being pessmistic, but when I chucked it up into the lathe and checked runout on the valve face, sure enough, it is indeed bent. Time to get a new exhaust valve, and re-check squish to make sure I didn’t do anything incredibly stupid. I know I learn all my lessons the hard way, but now its really starting to hurt!
February 22nd, 2008 at 3:56 pm
Rocky has a good eye. I followed the link to his site and found some of the best old motorcycle pictures I have ever seen. If you’re into bikes, follow the link and visit the pictures page. That picture of Rollie Free going 147 at Bonneville is awesome, Clem Murdaugh at Muskegon and the Murdaugh’s marauders, Wow!