Post
by heyyou » Sun Jan 11, 2009 2:06 pm
I haven't had a lot of luck with questions I've had with this forum, so I thought I'd pay it forward and share a technique I used to free up a stuck piston on a CB77 parts bike I'm dismanteling. I'm restoring three Hondas at the moment two 79 CBXs and one 64 CB77. Maybe folks will be willing to share their experiences with me.
The left side piston was stuck a little below TDC and it so happens that the cam chain link was near the top of the head so no cutting was required. After removing the head I started soaking the stuck cylinder with penetrating oil and scrapping the exposed cylinder to remove any visable rust. It appeared the piston was not going to move regardless of how long I let it sit soaking up penetrating oil. Taping the piston with a plastic drift and turning the crankshaft only left me thinking I'd end up with a cracked piston if I kept that up and went for a bigger hammer. The photos below show the use of a machined cylinder cover plate sealed with an o-ring and pumped with a grease gun to free up the piston. This is technique works great and can sometimes be used with the head in place by pumping through the spark plug hole (with an adapter) as long as you can close the valves and get good a seal.
I'll add some the pics. below. Cheers!
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Attachments
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- Success! Now its time to clean up the mess.
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- pumping grease into the cover plate and ready to insert the other zerk fitting
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- bottom of cover plate
