Topic: How to remove cylinders with a stuck piston

[cafe400f]

I have read of another method to free a stuck piston, a little more involved than most.  You take an old spark plug, break/ cut off the ceramics, drill out the electrode, tap it and insert a grease zerk.  With the head fully mated to the cylinders, screw in your homemade zerkplug into the offending cylinder spark plug hole and tighten her down.  Make sure both valves are close by whatever means necessary, remove cam, etc.  Proceed to attach your grease gun to the new zerkplug and pump the cylinder full of grease.  From what I have read, the increased pressure in the cylinder from the grease filling the cylinder and continued added pressure (keep pumping the grease gun)  will cause the piston to ultimately free up.  As a result of the pressue, something has to move, the cylinder walls can't, the valves will only close further and tightly seal, so the only variable is the piston.  I haven't tried this method yet, but it sure sounds very logical to me.  I'd like to try this next time I have a frozen motor or also try the gear puller method ... link below.  The only risk I can think of with the gear puller method is if the rings are solidly rusted to the cylinder, you might risk the legs of the gear puller cracking the head or just punching through the piston.

http://forums.sohc4.net/index.php?topic=70136.0

[faux fiddy]

and if the piston rings are good and rusted to the walls bunt trauma is the only way those cylinders are budging. 

Baseball bat?

[Bootlegger56]

Similar to cafe400's post but I have never tried it on a bike but it has worked on other engines.  You can typically use a compression tester fitting for the plug hole or buy a leak down test adapter at the auto parts store.  Loosen the valve adjuster to insure they are shut.  Fill the cylinder up with penetrating oil of choice.  Hook up the air hose and jack up the pressure to whatever you have.  Let her sit.  Every once in a while while walking by give the cylinder or head a smack with a dead blow (use judicial force).  Heat can also be applied with a heat gun or propane torch.  Again common sense is in order!

[terza96]

Sorry guys I dont want to spam a tread but need to ask :
I am newbie ,that started my first resto on my CB 750 1972.I'll post some pictures when I;m allowed.
But after took apart hole bike ,started working on engine.Before that red lots of this forum to see am able to do it.Have a faith that  you guys going to help me with this .Engine was seized wasn't any chance that it could move it.Try everything !
After I took of camshaft and camshaft holder sow that one of the bearing surfaces on camshaft and camshaft holder is badly weared .That is first one after sprocket
I'll post a picture later .
So I am wondering can I used one from same bike year 1975 to replace it and camshaft and holder ?I bought  another motor CB 750 1975
Thanks guys

[lucky]

Man, I hope I never get a motor that has been...
"LUMBEED"...       

 There is a lot of other ways to do this.. without hurting your cylinder or cases..

WOW broken fins and stuff!!!! I'm outta here.

"Hammer time" ooooowww !!!

[Roach Carver]

You should be fine to use the complete cam assembly from another bike. Another important question is what caused that damge. Oil starvation of some sort i think. If it is plugged oil passage then it will just happen again.

Sorry guys I dont want to spam a tread but need to ask :
I am newbie ,that started my first resto on my CB 750 1972.I'll post some pictures when I;m allowed.
But after took apart hole bike ,started working on engine.Before that red lots of this forum to see am able to do it.Have a faith that  you guys going to help me with this .Engine was seized wasn't any chance that it could move it.Try everything !
After I took of camshaft and camshaft holder sow that one of the bearing surfaces on camshaft and camshaft holder is badly weared .That is first one after sprocket
I'll post a picture later .
So I am wondering can I used one from same bike year 1975 to replace it and camshaft and holder ?I bought  another motor CB 750 1975
Thanks guys

[terza96]

Thank you Roach Carver for answering.
In a mean time I discovered that last on the left piston rod is also stuck ,actually the first one from the bottom on the picture.
Three of them moving freely and that one is not moving.When u push that one it's move the hole crankshaft !
Also On the cylinder head where the cam chain getting through i can see a wear of cam chain left and right from cam chain tensioner.it look like the chain wasn't tension-ed properly.I am not expert but that I was thinking .


Because of that I don't feel confident to open further lower case of the engine .what do u think ?

[boatsdickson]

Terza, you werent asking me but Ill chime in. Id tear the whole dang motor apart judging by the upper end pictures. My overactive mind is visualizing lots of ugliness floating in your lower cases, metal pieces and chunks possibly. Guess it depends on how  far your willing to go but putting it back together now seems simply half correct.

Just my 2 pennies & sometimes that aint worth squat  ......Boats

[Roach Carver]

I will go along with that. You are out of my territory now but there is a HUGE knowledge base here. I would start a new thread of your own in the project section. You will get plenty of help. Carry on.

[terza96]

Thank's guys very much I'll do that

[terza96]

Ok guys I started my own build topic on the Project shop called First try restoration ,tons of photos
Thank u and welcome I need your help
Zoran

[rb550four]

     I know this is an old thread, Depending on the condition of the engine some will break free before others. My main goal when starting bike #1 was to save it from the scrap heap,now 20 bikes later , I'm still buying scrap worthy machines that are seized just to save them, I have tried  almost everything mentioned here  except for the BFH or the baseball bat . I've had motors full of concoction hanging from the rafters for weeks, hanging from the rafters in frame, tried heat and ice methods....all that.
   The best, the  easiest, the least amount of damage  is the grease method that cafe 400 mentioned at the top of this page.
    I used to start by cutting off the cam chain because you can't get to the 2nd bolt, remove the top end and hang it. That's just history here for me.
   Soak the cylinders for a while, with the top end still on, pull all the plugs, add zerk plug in the cylinder with the piston in a high position, pump in the grease. Viola ! the engine is free to dismantle. It's just as simple as that .
   No broken fins ,beat up parts, or knuckle busting with a breaker bar... it's just done...and most of all, you don't have to wait for weeks till it decides it's ready to get loose. Done!
    I didn't think this thread was complete until this method was tried and proven more than a few times and, it has been more than a few times, and for me , this method is the only sensible  answer.

[chewbacca5000]

     I know this is an old thread, Depending on the condition of the engine some will break free before others. My main goal when starting bike #1 was to save it from the scrap heap,now 20 bikes later , I'm still buying scrap worthy machines that are seized just to save them, I have tried  almost everything mentioned here  except for the BFH or the baseball bat . I've had motors full of concoction hanging from the rafters for weeks, hanging from the rafters in frame, tried heat and ice methods....all that.
   The best, the  easiest, the least amount of damage  is the grease method that cafe 400 mentioned at the top of this page.
    I used to start by cutting off the cam chain because you can't get to the 2nd bolt, remove the top end and hang it. That's just history here for me.
   Soak the cylinders for a while, with the top end still on, pull all the plugs, add zerk plug in the cylinder with the piston in a high position, pump in the grease. Viola ! the engine is free to dismantle. It's just as simple as that .
   No broken fins ,beat up parts, or knuckle busting with a breaker bar... it's just done...and most of all, you don't have to wait for weeks till it decides it's ready to get loose. Done!
    I didn't think this thread was complete until this method was tried and proven more than a few times and, it has been more than a few times, and for me , this method is the only sensible  answer.

I have no doubt this work since it is how I remove stuck brake pistons.  One word of caution to those who are trying this method make sure you find the cylinder that is on the compression stroke.  Both valves need to be closed to move the piston, or the grease will shoot out the open valve.

Now if rb550 could hook me up with one of those zerk plugs I would be most grateful.  And no, I have not be able to smash the electrode out of a spark plug yet.  Guess I am just not that Mac Guyver.

[chewbacca5000]

Found this link it showd step by step how to get the spark plug insulator out.

http://cyclepsycho.com/greaseplug/greaseplug.html

The key is to cut the grounding strap and smash the insulator to bits and then flip over and hit it from the other side.  Was not that bad.  I don't like the grease fitting he uses instead I am going to try tapping with 1/8" x27 npt pipe thread which is the same as the grease gun.

Edit:  After smashing out the electrode I used a  3/8" drill bit and and drilled 3/4 the way down leaving the last bit of material for stop for the grease fitting.  I then taped withtje 1/8" x 27 npt tap.

Note: You need to use the metal tube that comes with the grease gun as the rubber hose will burst and shoot grease everywhere.

[XC204]

I know that this is an old post but I was able to gently remove my cylinders without damaging them or the pistons
I couldn't copy the photos but you can look at the first page of this post http://forums.sohc4.net/index.php/topic,101767.0.html