CB72 stuck piston problem - again!

gerrymoore · Post by **gerrymoore** » Tue Jan 17, 2017 3:51 am

Hi Malcolm..thanks for the info. That's exactly what I have..the angle and a 10mm bolt! One piston is about 6-8mm from TDC so hopefully I should be OK...??

I'll try the coke method...I never drink it.... and possibly now I know why!!

G-Man · Post by **G-Man** » Tue Jan 17, 2017 5:33 am

If the bottom crankcase is removed then the crank is free to move away from the barrel.

You also get the chance to 'see' the underside of the pistons/liners.

G

malcolmgb wrote: It's also important to note that if the pistons are at either TDC or BDC you will have major problems because you are the just pushing against the con-rod and the crank will not turn enough.

gerrymoore · Post by **gerrymoore** » Tue Jan 17, 2017 6:11 am

Thanks for the input Graham. A friend has just pointed out that, because the crank is free to move down, I can push down on both pistons at the same time which may help as all the forces will be equal...this is right isn't it ????

Gerry

G-Man · Post by **G-Man** » Tue Jan 17, 2017 6:37 am

Gerry

When you do the trick with the "puller", I would try and use a plate which picks up on as many studs as you can and that will spread and balance the load better. You don't want to be breaking studs or pulling them out of the case.

Yes doing two at the same time may be helpful.

It just occurred to me that if you turn the whole thing upside down you can fill the underside of the pistons with release agent and try and attack the corrosion from the other side for a while.

The piston is drilled just below the oil ring so that might help get the fluid to where it is needed.

Good luck!

G

gerrymoore wrote:Thanks for the input Graham. A friend has just pointed out that, because the crank is free to move down, I can push down on both pistons at the same time which may help as all the forces will be equal...this is right isn't it ????

Gerry

LOUD MOUSE · Post by **LOUD MOUSE** » Tue Jan 17, 2017 6:39 am

The pullers Bill and I use are Chicken Foots.
4 places for studs to pass through.
Previous message.
"I recommended 2 tools at the same time and go back and forth". ...................lm

gerrymoore wrote:Thanks for the input Graham. A friend has just pointed out that, because the crank is free to move down, I can push down on both pistons at the same time which may help as all the forces will be equal...this is right isn't it ????

Gerry

gerrymoore · Post by **gerrymoore** » Wed Jan 18, 2017 3:13 am

I've done as Graham suggested and filled the bottoms of the pistons with the 'mix'. I'm away for a couple of weeks now so will see if anything has happened on my return.....

brewsky · Post by **brewsky** » Wed Jan 18, 2017 6:18 am

This cylinder and intake port were both full of rust, and soaking and a hammer was futile.

So I filled it full of atf/acetone mix, heated and cranked it down as much as I dared each day, and left it under pressure.

After a couple weeks I heard a loud BANG as I walked away....thought the wood had shattered, but the piston had popped loose!