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Author Topic: A great technique to remove stuck pistons  (Read 12197 times)

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Offline swan

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A great technique to remove stuck pistons
« on: February 25, 2011, 05:22:45 AM »
A discovered a new way to remove a frozen piston from a cylinder and it works great! This bike is British, but this technique will work on old Hondas too. My BSA Gold Star has been sitting for more than 40 years and the rings and piston were severely frozen to the rusty cylinder wall.

40 years of rust

I cleaned and scrapped off all the visible rust and soaked everything in different solutions of ATF and acetone, PB Blast, Seafoam Deep Creep, DOT 3 and Marvel Mystery Oil for several months with no movement whatsoever. Next, I tried Naval Jelly, a gelatinous phosphoric acid, to attack the rust on the frozen pistons. Still no movement.

It soaked everything for another week in Marvel Mystery Oil and was going to set up an electrolytic reduction to remove the rust and free the piston, but stumbled across another technique and it worked great! From an antique motor forum I found B. Kedrowski’s 12 steps to removing a frozen piston. He and another forum member have used this technique on more than 100 old and rusty tractor motors. They recommended scrapping away as much rust as possible, using a 50/50% mix of ATF and gasoline with a bit a cloth as a wick, ignite it, let it burn for an hour and then cool down. The expansion and contraction by the heating and cooling cycle allows the ATF to work its way down past the rust and lubricate the rings.

Fire and ice

I then pounded the piston with a large wooden drift and a dead blow hammer and I finally had movement.  Several more whacks pushed the piston down and I was able to finally release it from its rusty prison. Free at last, free at last!




I hope this technique will get some old Hondas back on the road.
Learn more about my 1962 BSA Gold Star barn find restoration.




 
« Last Edit: December 05, 2012, 01:53:30 PM by swan »
1975 CB400 F cafes, 1974 CB750 K4 Cafe, 1966/1976 Triumph/ Norton Triton Cafe and 1962 DBD34 BSA Gold Star Clubman.

CB750 build http://forums.sohc4.net/index.php?topic=52551.0

Offline dragracer

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Re: A great technique to remove stuck pistons
« Reply #1 on: May 11, 2011, 12:48:25 PM »
Good method but the won't let me play with fire :'(.

Offline HondaMan

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Re: A great technique to remove stuck pistons
« Reply #2 on: June 02, 2011, 02:52:21 PM »
I can't wait to try it! Gotta do this to the next one...  ;D
The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
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Offline bjatwood

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Re: A great technique to remove stuck pistons
« Reply #3 on: August 24, 2011, 07:51:07 AM »
+3  ;D Excellent tip!
Brian
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Offline 1BadCB750

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Re: A great technique to remove stuck pistons
« Reply #4 on: November 19, 2012, 09:50:07 AM »
This method worked a treat! Been trying to free a K1 motor for many months. Tried WD-40, PB Blaster + ATF, white vinegar. No luck. Last night, the motor came free! And with very little effort too. I had 2 cylinders that looked just as bad if not worse than the picture in the original post.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: A great technique to remove stuck pistons
« Reply #5 on: November 19, 2012, 10:09:15 AM »
And considering it's getting to be winter time in North America this would also make a wonderful garage heater!  ;D
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline 1BadCB750

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Re: A great technique to remove stuck pistons
« Reply #6 on: November 19, 2012, 11:30:40 AM »
And considering it's getting to be winter time in North America this would also make a wonderful garage heater!  ;D

Mmmmm, the yummy smell of burning ATF. ;D

Offline swan

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Re: A great technique to remove stuck pistons
« Reply #7 on: November 20, 2012, 10:26:57 AM »
This method worked a treat! Been trying to free a K1 motor for many months. Tried WD-40, PB Blaster + ATF, white vinegar. No luck. Last night, the motor came free! And with very little effort too. I had 2 cylinders that looked just as bad if not worse than the picture in the original post.
Yeah! I am glad it worked for you.
1975 CB400 F cafes, 1974 CB750 K4 Cafe, 1966/1976 Triumph/ Norton Triton Cafe and 1962 DBD34 BSA Gold Star Clubman.

CB750 build http://forums.sohc4.net/index.php?topic=52551.0

Offline madScientist

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Re: A great technique to remove stuck pistons
« Reply #8 on: November 20, 2012, 12:03:28 PM »
I have an old 428 cobra jet engine with stuck pistons...this should be fun to do in it!
You CAN do great things...with enough beer.


78 cb750f
http://forums.sohc4.net/index.php?topic=113293.0
70 CL350 Street Tracker / Cafe
http://forums.sohc4.net/index.php?topic=125641.0
77 cb750A
74 cb125s
83 KZ1100ltd
76 GL1000

Offline Prospect

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Re: A great technique to remove stuck pistons
« Reply #9 on: November 20, 2012, 01:02:46 PM »
I don't think I would do this with the bottom end still intact.  I'd disconnect the connecting rods from the crankshaft and then take the cylinders off and try it.   
1969 CB750  Sandcast
1971 CB750K1
1972 CB750K1
1975 CB400F
1974 Harley Davidson XLCH
1957 Harley Davidson Panhead

Offline Big C

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Re: A great technique to remove stuck pistons
« Reply #10 on: January 07, 2013, 06:15:27 AM »
I'll try it tonight. I like the garage heater angle, too!

Offline Sawdust723

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Re: A great technique to remove stuck pistons
« Reply #11 on: March 10, 2013, 05:24:23 PM »
That's a great idea! I have also found kerosene or diesel fuel to work excellent( with out lighting it on fire )
1974-77 cb750ish
1971 cb350 twin

Offline RAF122S

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Re: A great technique to remove stuck pistons
« Reply #12 on: March 10, 2013, 06:40:50 PM »
Just melt down some white styrofoam in the mix and you can have some homemade napalm...
David M
Blountville, TN
my current collection of bikes:
'65 Honda CA95 Benly Touring 150 (running awaiting restoration-storage) 
'70 Honda S90 Sport 90 (yes it is a Nov 1969 production, labeled as a 1969 US market bike, in storage)
'74 Honda CB550K0  (refreshing, returning to street after 25 yrs...working on it)     
'78 Honda CX500 (plastic maggot, plated & licensed - not riding)         
'81 Honda C70 Passport (plated & licensed, storage)

Offline BGbikes

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Re: A great technique to remove stuck pistons
« Reply #13 on: August 06, 2013, 04:53:21 PM »
Wish I would have seen this method a couple days ago. I just worked on getting a cb350f motor loosened up three days ago. Luckily only one of the four pistons was stuck and I got it loosened up. Soaked it for 6 months in marvel mystery oil and a few days of liquid wrench did the job.
1970 cb350
1971 cl350
1972 cb350f
1974 cb350f
1978 cb550k
2007 victory vegas

 

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