FWIW, I replace the pushrod tube seals on my /7 two days ago. All I did was remove the exhaust and carburetors then set the cylinder to TDC and torque (per Oaks recommendation) the cylinder bolts incrementally until they were loose. The rocker assembly and pushrods were removed and oriented for replacement in the same locations. The cylinder was slid out, seals replace, base recoated with Hylomar, o-rings inspected, and then slid back. The valve train reinstalled in the correct location, adjusted for rocker arm end float, retorqued (incrementally), exhaust and carburetors replaced.
Mine had no gasket or cylinder base o-ring to replace and the pushrod seal o-rings looked OK. I used lighter fluid (Ronsonol) to lubricate the new seals. The most difficult part was cleaning around the cylinder to remove old Hylomar, clean, and recoat. Getting Hylomar was not that easy. The valves were adjusted last before a test ride. Good luck!
Stan_R80/7 screwed with this post 10-09-2012 at 05:17 AM
Reason: made o-ring plural