Cylinder Puller

[Toystoretom]

Some of you may have the same problem I have... that is a seized motor due to stuck pistons. I made this puller to un-stick things. This is by no means my idea as this device has been used by many people on many different bikes, I am simply sharing this as it applies to a Bridgestone 350 GTR.

I took some steel 1/4 ' plate and measured the locations for the 4 cylinder studs on my stuck GTR and drilled 1/2" holes there. I also drilled a hole in the middle and welded a nut to the plate. I then greased up a bolt and threaded it into the nut.



I pulled the cylinder studs from the bike, double nut them and screw them out. I then tapped the holes, I think I used a metric 10-1.50 tap (don't quote me on that, use what ya got and fits and you will need 4 bolts to thread in there.)




To be continued....

[Toystoretom]

I then installed the puller by threading in the 4 bolts:


Then... crank down on the center bolt to pull the cylinder:


Here is the piston, very nasty:


Here is the cylinder after being pulled.



I put a metal disk on top of the piston to distribute the force of the bolt being applied to the piston, so it wouldn't punch a hole through it.

Notice that there is a crack in the base of the skirt. The skirt is super thin in that spot and if the piston is really seized it will crack that skirt. I suggest applying heat (MAP gas or Oxy Aceteline) to that spot as soon as it is revealed. I had soaked that cylinder with Seafoam and PB blaster for weeks. That is the second cylinder that has cracked like that that I have pulled.

I am still looking for a good useable left cylinder (or NOS) so keep me in mind!

[ColoStone]

I am guessing the method of tapping the holes in the cylinders is done knowing you will no longer use them ?
  or will it be OK if the cylinders are reused to have the holes threaded like that ?  with chance my cylinders were going to be in good shape (with the low mileage on the bike ) I was too chicken to be that aggressive (see " it be stuck "). But in the case of bad cylinders I really like that home made tool
           Thanks
               Randy     

[Toystoretom]

Threading the 4 stud holes won't hurt a thing and if the cylinders come off cleanly they could most certainly be reused with those holes threaded. You could try pulling the cylinder using the studs themselves..... but..... if the crankshaft is frozen and won't turn (or the piston is stuck at the top of the stroke) you could really mess something up. It is probably best to thread the holes and try and pull the cylinder up and away from the crankcase.

As you can see, this particular motor is really stuck. The crank is stuck, the cylinders were completely seized. When I pulled the heads off I could tell just by looking that things were not good.

[ColoStone]

Well I hope you can get some jugs and I will keep a look out around my neck of the woods for you
          Thanks
              Randy

[rocketman]

 Nice post Tom. Great pictures and step by step.  Thanks,Mark.

[Gerrit]

I wouldn't throw such a cracked cylinder away, it can most probably be repaired. Late TZ250 cylinders quite often show cracks in the thin bridges between the auxiliary ex ports and the main ex port. After the original plating is removed the crack is ground out and filled by welding, the bridge is then reworked to its original shape. Such a repair is also possible with damage as in the photos in my opinion. Of course the cost of the repair has to be added to that of replating the bore, but how much do new cylinders cost- assuming you can get one, that is?

[slawsonb]

Gerrit, thanks for bringing this thread back. I have searched for this exact information and did not find. (Guess my search skills could use some work.)

Tom, I am in the throws of what sounds exactly like the situation you experienced. I have been soaking with PB and SF for weeks and no movement. I'm going to make a tool like this unless someone has one they would sell or loan. The parts bike I am trying to extract the cylinders from has exactly  the type I've been looking for (anti-ring pins, improved flanges, no side dimples) but based on your experience, I am not optimistic I will get anything but a bad headache from this exercise or at best a very expensive repair/replate project. C'est la vie!

...bert

[Gerrit]

I'm in the same situation with an incomplete engine I bought recently. LOTS of WD-40 but so far the pistons won't budge- bummer! I think I'll try gasoil instead; that stuff penetrates better than any so-called penetrating oil in my experience. Plus, a litre of gasoil is cheap compared to a tin of WD-40.

[slawsonb]

Gerrit, sorry to hear you are suffering the same fate...I think the dissimilar metals corrosion theory raised by Tom is a very plausible explanation for this dilemma (iron rings against aluminum piston plus time in a humid environment causes a galvanic reaction and expansion behind the rings locking them against the cylinder wall). The issue is getting penetrant behind the ring.
I have seen my situation go from no drainage past the rings at all, to after 3 weeks of alternating PB Blaster (penetrating catalyst (so called)) and SeaFoam (a gasoline additive intended to clean valves ,etc.) that now over night the combustion chambers will empty. My fear is this is just passing between the ring and the cylinder wall and detouring away from the piston/ring interface. Cause for optimism? Wish I knew...
My next step will be to split the cases and flip the engine over so as to apply these elixirs to the bottom side of the cylinder/ring interface. This will also cause the fluids to run in the opposite direction from the topside up orientation and may facilitate actually getting something in behind the rings.
Wish me luck...I really want to save these cylinders...
...bert

[Gerrit]

I think the problem lies more in the piston corroding rather than the rings. The cause is galvanic corrosion, induced by the potential difference between two metals. The difference between the aluminium piston and the chrome cylinder wall is greater than between the iron rings and the cylinder, hence the aluminium will corrode first. Ships usually have sacrificial zinc anodes attached below the waterline to prevent corrosion of the steel hull and bronze propeller. The zinc disappears first because it is lower in the potential range.

If you are willing to wait a few centuries or so, the piston will have corroded so much that it will probably drop out of the bore by itself!

[slawsonb]

Agree completely... the piston is the culprit. Growth of aluminum oxide behind the ring...anyway, I'm pretty sure I don't have anything like a century (or a few...) to wait.  I'm actually surprised I have been this patient...lol...
...bert

[Skinny]

Maybe this has been discussed, but....
My shop has given up on all commercial penetrating
Snake oil for years now. All the claims and hype are
just that.
A simple mix of 10-15 percent acetone and ATF works
much better and is so much cheaper.
I use less acetone on long soaking and more for fast
penetrating.
Any good light oil woks- I have even used vegetable oil.
I have freed stuck pistons with this concoction, plus
all those seized little buggers that plague my life.
Check out the study by Drexel University.

https://www.engineeringforchange.org/news/2012/08/14/how_to_make_penetrating_oil.html

Skinny

[Gerrit]

Bert, the oxide behind the rings is a very minor problem compared to the oxide forming between piston skirt and cylinder bore- the latter is simply a much, much larger area.

Skinny, thanks for the tip. Will try to get some acetone at the local chemist's tomorrow.

[Toystoretom]

If you buy acetone around here they think you are making meth.

Heat will get it loose, but you need a lot, as in oxy- acetylene (don't melt the cylinder). After heating maybe hit the pre-installed puller with an impact gun.

If that doesn't work get out the air chisel and break up the piston, but be careful of the connecting rod and cylinder walls. It may be best to drill a few well located holes in the piston to guide you before you start to hammer on it.

[slawsonb]

Skinny/Gerrit, thanks for the info...Looks like trying the acetone/veg oil mix will be next...
...bert

[Skinny]

I forgot to say that Marvel Mystery Oil is my favorite for the mixture, but increases cost.
Skinny

[slawsonb]

At this point, I just want to save those cylinders, so MMO it is...Thanks...
...bert

[Gerrit]

I don't think Marvel Mystery Oil is available over here, so for now it's acetone and sunflower oil. if that doesn't work I'll place the cylinders, crankshaft and upper crankcase half in an old oil drum and submerge it all in gasoil for a month or so.

[slawsonb]

I split the cases and have the cylinders soaking in the topside down orientation with penetrant poured into the exhaust ports. In my case, the rings are at about the center of the exhaust port,  and fluid seems to be surrounding the piston...still will change to the acetone and oil mixture on the next soak cycle...
...bert