Topic: New plan for really stuck pistons - Bottoms up attack approach

[paulbaker1954]

OK I have tried it all, MMO for 2 weeks, rocking in gear, plentiful heat, big hammer on top of pistons with head off and them pistons are going nowhere. Also tried leverage with 4x2 and breaker bar under cylinder block but all I am going to do is smash fine so have been thinking about a new plan of attack and have a few questions.

Basic idea is not to attack the problem from underneath by splitting the engine cases, undoing the big ends, remove the cylinder block complete with pistons and conrods and then push each piston out in a hydraulic press. Further logic here

1)I am doing a full engine refurb anyway so will have to split the cases at some point anyway

2) The seizure (highly unlike given that the head wont move anyway) may be big end bearing, primary chain god knows what else at the bottom end......

So now my key questions before I start on this new attack from the bottom:-

A) Is my though process rational and sensible (please no more replies on freeing the jugs by other means - they are all exhausted!!!!)

 B) Given that I can't rotate the crank will I still be able to get a socket on the big end nuts (2 pistons are at roughly TDC) to free the crank from the pistons so I can pull of the head complete with pistons and rods. I have looked at a few pics and theoretically this looks workable. The bolts should be visible at whatever the piston positions are I think.

[calj737]

Your approach may work, but theres no guarantee of clearance from below without being able to rotate the crank. Obviously, cut the chains an remove the rod caps. Keep them numbered and oriented too with their nuts.

It wold be very interesting to see into your engine form above and below when you get it opened up. I would also remove the starter before inverting the cases, and clutch basket.

You say the head won't lift free? If so, is the cam chain guide out yet? Do you have all nuts (12) completely free and the 4 bolts beneath the breather cap?

[Powderman]

Did you mean this?     "Basic idea is NOT to attack the problem from underneath"

Or this?         "I can pull of the HEAD complete with pistons and rods."

[Powderman]

You say the head won't lift free?

Go back and read his first sentence.

[Stev-o]

Try Cal's approach: pour kerosene on the pistons and start it on fire!

Not joking.

[strynboen]

you can  bolt the head and cylenders together...use pinn bolts... and press the pistons down vith a grease pump..but it need the crank lossen from the rods..to let all pistons move Down at same time

[Powderman]

you can  bolt the head and cylenders together...use pinn bolts... and press the pistons down vith a grease pump..but it need the crank lossen from the rods..to let all pistons move Down at same time

How will all the pistons move DOWN if they are not connected to the crank? The crank has to turn for any of the pistons to be pushed down. Can the head be bolted to the cylinders with anything other than the studs? What is a PINN bolt?

[strynboen]

pinn bolts are just thredet shafts bayed in meters..they are often soft iron rolled threds..but fine for easy fixes

i  just put a grease nippel in the spark plug..and pump grease in at 100-500 psi or more in the kompresion champer...it often brake the piston free
but it needs teight valvets..have only used it on 2 stroke piston in top pos..but it Work in all types of Lock pistons
have not thek up on the problems bolt the head/ cyl together..but vhy not..

[Powderman]

pinn bolts are just thredet shafts bayed in meters..they are often soft iron rolled threds..but fine for easy fixes

i  just put a grease nippel in the spark plug..and pump grease in at 100-500 psi or more...it often brake the piston free
but it needs teight valvets..have only used it on 2 stroke piston in top pos..but it Work in all types of Lock pistons
have not thek up on the problems bolt the head/ cyl together..but vhy not..

This would only work on the hole that the valves are closed in. As soon as the crank moves and a valve opens you would need to move to the next hole with valves closed. Sounds like a lot of grease. Great fix for caliper pistons, not so sure on an engine piston.

[strynboen]

you need 750 cc grease..or a bit more

[przjohn]

If you have exhausted ALL other attempts from above your game plan sounds feasible. The biggest benefit it would seem to me is that now you can work on the cylinders individually. Instead of trying to get 4 pistons moving at once you can get them freed up one at a time. Very interested to see how you make out.

[calj737]

Try Cal's approach: pour kerosene on the pistons and start it on fire!

Not joking.

Exactly. As long as the "seized" engine is not a crank seized, this will release the pistons. Guaranteed.

[paulbaker1954]

Watch this space !!!

[RevDoc]

Watch this space !!!

As oppossed to "Hold my beer and watch this s..t!" ?

[paulbaker1954]

OK so the bottoms up approach is fine as you can get at the big end bolts easily and once they were undone the block and Pistons came away fine.

So now I have a cylinder block with 4 Pistons stuck in it and four dangling con rods

Next step I put the whole lot in the oven and then whacked the Pistons but all that moved was the liners !!!!

Them Pistons must be amazingly stuck

So now off to local engineering shop to see what they can do

[rinkeldekinkel]

Hi Paul,

I have had the same problem, bike (750 K1) stood for 40 years moist.
cylinders where stuck as hell

i tried heating them with oxy propane, to no success.

In my opinion, if you heat the piston only you will burn the gum, and rust that is leaving it stuck, and after it cools it will free up, heating the complete assembly will leave less heat for burning rust and gum right at where it is needed.

Then I tried my TIG torch on the AC, this helped amazingly quick, within a couple of minutes of waving my torch on 200 amp or so
at each piston i was able to turn the crank by wrench! after a few hits with a wooden block ad hammer.

Hope this helps, i tried a few  liquid remedies before, but not a drop had penetrated, the gum that was surrounding my piston rings...
not a drop,

Good luck!

[calj737]

with the block free and pistons stuck, "whack" from above only. The liners will drive upwards as you discovered. Or, remove the liners with the pistons still inside and heat only those components. This is MUCH MORE FRAGILE a method as you can very easily damage the liners.

[Bodi]

Once you have the cylinder section loose with the pistons stuck in it, any machine shop will have a hydraulic press which will easily push the pistons out.

[madmtnmotors]

+1

Press the pistons from above pushing them out the bottom.

[paulbaker1954]

Hooray they are free, bottoms up approach worked fine but i had to get the b******* pressed out at my local machine shop. They were just REALLY REALLY tightly seized.

only cost me £80 and for that they honed the bores and also removed and retapped one of the case studs that sheared.

I am beginning to believe this bike has only done the 13000 indicated miles as the bores show no wear and all the rest of the engine parts are in really good condition now i have them all stripped out

I now have the cases all squeaky clean and nearly ready to start putting it all back together

Next step is plastigauge the bearings and measure the bores and then i will really find out if this mileage is right