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Discussion Starter · #1 ·
The pistons on the bike I bought to restore are seized and I cannot seem to get the cylinder block to budge. I heated the pistons up a bit to see if that would loosen them up and also tapped the bottom with a hammer to no avail. Any suggestions?
 

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...have you tried leaving WD40 in the barrels for a few days?Time is the best method...
 

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I perfer Kroil penatrating oil and lots of patience for this job. Let it soak over night and lightly tap the piston down and the barrel up. Repeat as need, just like shampoo.
 

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The pistons on the bike I bought to restore are seized and I cannot seem to get the cylinder block to budge. I heated the pistons up a bit to see if that would loosen them up and also tapped the bottom with a hammer to no avail. Any suggestions?
This is a two stage process.

Pistons This takes time, often a lot of time. Pour penetrating oil into the barrels and leave for several days. A good penetrating oil is a 50/50 mix of Acetone and ATF. There is no substitute of time. It might take several weeks.

Barrels If, after unseizing the pistons, you still cannot get the barrels to lift then try the following. Put nuts on each of the 4 corner studs with another nut loosely on top, or even better a large ball bearing on top of the first nut. Then slowly, a quarter turn at a time, raise the nuts that are on the corner studs. Do each nut in turn the quarter turn. You should find that the ball bearing or top nut soon makes contact with the lower fin of the barrel and acts as a jack. The barrel will very quickly lift off the crankcase with very little pressue. If anything more than quite gentle pressue is required then something else is wrong and needs to be investigated.
 

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Discussion Starter · #5 ·
I have had wd-40 in them for a few days to no avail. We will see how the other ideas work. Thanks!
 

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The pistons on the bike I bought to restore are seized and I cannot seem to get the cylinder block to budge. I heated the pistons up a bit to see if that would loosen them up and also tapped the bottom with a hammer to no avail. Any suggestions?
try putting the unit in the oven or heat the barrels from the outside that way if the barrels heat up first they should expand a fraction to allow the pistons poss to move just an idea has worked for me in the past IF YOU HAVE AN UNDERSTANDING WIFEY/MISSUS:eek::eek::eek:

needs are a must.....
 

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Discussion Starter · #10 ·
try putting the unit in the oven or heat the barrels from the outside that way if the barrels heat up first they should expand a fraction to allow the pistons poss to move just an idea has worked for me in the past IF YOU HAVE AN UNDERSTANDING WIFEY/MISSUS:eek::eek::eek:

needs are a must.....
Can't say I am old enough to have a wife yet but I have been told to be careful if I ever find a woman lol ;)
 

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Discussion Starter · #11 ·
try putting the unit in the oven or heat the barrels from the outside that way if the barrels heat up first they should expand a fraction to allow the pistons poss to move just an idea has worked for me in the past IF YOU HAVE AN UNDERSTANDING WIFEY/MISSUS:eek::eek::eek:

needs are a must.....
Can't say I am old enough to have a wife yet but I have been told to be careful if I ever find a woman lol ;)
 

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The pistons on the bike I bought to restore are seized and I cannot seem to get the cylinder block to budge. I heated the pistons up a bit to see if that would loosen them up and also tapped the bottom with a hammer to no avail. Any suggestions?
This very matter has been raised before and some very effective method was posted that would help you no end. It may well have come up at britbike.com

I really should be more like Henry Anthony and keep a log of sorts so that I can retrieve them at will. Britbike's search engine is pretty useless, but it may offer you something.

It may well have been here the answer was given. Oh my poor memory......... I'm getting more like Jim Ballard every day. RR
 

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Don't waste your time trying to heat the barrel.
If you want to heat anything,heat up a pint of ATF to about 350 degrees F.Flash point is around 400 degrees,so be aware if you overheat it there will be fire and you'll have to put a lid on the container to smother it.
Pour the hot ATF into the cylinders onto the pistons.Take the ATF out when it cools down.You can do this a few times.Each time the pistons expand (when hot) and contract when they cool,it will help.
A good soaking with penetrating oil will help too.Lots of patience will help.

If all else fails,you can put the head back on and use hydraulic pressure through the sparkplug hole.1500 psi would get around 9000 lbs force on the piston.You can get 5000 psi with a grease gun.
How far down from TDC are the pistons?
 

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Should you loose patience using penetrating oil, you can take a drill and punch a series of holes thru the top of the piston to weaken it and then give it a couple good cracks with a hammer to break the piston into pieces.
 

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atf and acetone

I'd go with 50/50 ATF and acetone. Let it soak for a few days then thwack the hell out of it with a mallet and piece of 2x4.

I did mine like that but the barrel and piston were toast so I used a wire brush and a pokey tool to really get down to it. I also used heat (propane torch) but I don't know if that helped.

Do you have a picture of it?
 

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Discussion Starter · #17 ·
Don't waste your time trying to heat the barrel.
If you want to heat anything,heat up a pint of ATF to about 350 degrees F.Flash point us around 400 degrees,so be aware if you overheat it there will be fire and you'll have to put a lid on the container to smother it.
Pour the hot ATF into the cylinders onto the pistons.Take the ATF out when it cools down.You can do this a few times.Each time the pistons expand (when hot) and contract when the cool,it will help.
A good soaking with penetrating oil will help too.Lots of patience will help.

If all else fails,you can put the head back on and use hyraulic pressure through the sparkplug hole.1500 psi would get around 9000 lbs force on the piston.You can get 5000 psi with a grease gun.
How far down from TDC are the pistons?
I believe they are tdc? I will put up a picture
 

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Discussion Starter · #18 ·

IMG_8880 by eamann665, on Flickr

(Before I put the ATF and Acetone in. It has been sitting for a day now.)

I have been going out every couple of hours and hitting it with a bit of force using a piece of wood and a rubber mallet. I would really like to keep the pistions in good condition though as I want to keep the bike as close to stock as I can. Obviously some parts have to be replaced.
 
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