What to do with old pistons

[Angus]

Storing away bits and piece not used in the rebuild and I was wondering should I keep the old pistons.
They appear OK no scoring or obvious damage.
Assuming they are worth keeping, is there any way to tell what they are, compression and + size as I can not see any markings on the crowns and it was over 30 years ago I took them out.

[Brian]

If they are still in reasonable condition I would keep them. You or someone else might be able to use them oneday.

As for compression, if the tops are concave (dished) then they are about 6.5-1, if the tops are flat with small cut outs for the valves then they are about 7.5-1 and if they have raised bevelled tops with cut aways for valves then they are about 8.5-1. There are of course other variants but they are the basic ones.

[JulianM]

In my opinion, anyone who fits old used pistons into their engine needs their head tested!
Throw them away and save someone from waisting time and energy doing a foolish thing.

They do make fun ash trays though!

Regards,
Julian

[muskrat]

 I tend to agree Julian. But, time, cost and location can have a bearing on things. I have two sets, both with under 1000 miles use, waiting for a rainy day. I would never re-use rings.
Cheers

[metalflake11]

I'm with Julian, this one, out of an old truck has given sterling service for years!

[JulianM]

I tend to agree Julian. But, time, cost and location can have a bearing on things. I have two sets, both with under 1000 miles use, waiting for a rainy day. I would never re-use rings.
Cheers

There are of course exceptions to every rule,   
It just makes me cringe though when you see adverts saying "Bike completely restored and rebuilt to the highest standards, no expense spared" and then you read, "Pistons re-ringed"   You can then judge how well the bike has been "restored" just by those few words.
OK a piston with no visible sign on the skirts of being run will I am sure be fine. In my opinion, Anything else should be turned upside down.
It's often cheaper to do it perfect in the first place!
Little example.
I just fitted 4 new Colsibro guides in my Scrambler head. I then reamed them all to make perfect. However!  I have several sets of reamers for 5/16 guides and was doing exhausts slightly larger than inlets.  Stupidly I picked up the exhaust reamer while doing one of the inlets.  Now I "could" just let it be and it would "probably" be fine.  But it would be so annoying if it were not. and it's so easy to do it now, (although highly irritating)  It would just not be good practice to let it be!   This is what I say about engine building or anything else, It is not a difficult job in itself, we all have hands and we can all physically do it.  The hardest part is policing yourself to be a perfectionist!  That is the only way you even get close to perfection. 

Regards,
Julian "P" for pedantic 

[Rocket Racer]

Personally I do keep an eye out for NOS and low mileage pistons, particularly the genuine BSA 8:1 road rocket ones that are light.
race engines don't mind slightly greater piston clearances (but with good rings)
Sure anything well used suitable for reference or emergency only, but I would prefer a good lightly worn genuine BSA piston over a new JP any day. I greatly dislike heavy pistons (which many new ones are)
I also do not rush to regrind cranks (if within tolerances), I just fit new shells.

Depends on intent for use and extent of wear.

When I put my race engine together the bores and pistons were already used and it pulls over 7000, no smoke and good compression. I'm happy.

[Rookie_V#60]

Hi,
I personally take old pistons to cast new parts, because piston have an high part of silicium ... giving very good casting parameters....
Cheers Rudolf

[muskrat]

 Clever little vegamite. ( oz slang saying for good)
Why not cast into new BSA pistons?
Cheers

[bsa-bill]

interesting answer to a question on a TV quiz
Q what is the most common element on Earth
A aluminium

I know certain cast aluminium has a good scrap price but takes a fair bit of it to count

[JulianM]

The most abundant element in the universe is hydrogen, which makes up about 3/4 of all matter! Helium makes up most of the remaining 25%. Oxygen is the third most abundant element in the universe. All of the other elements are relatively rare.
The chemical composition of the earth is quite a bit different from that of the universe. The most abundant element in the earth's crust is oxygen, making up 46.6% of the earth's mass. Silicon is the second most abundant element (27.7%), followed by aluminum (8.1%), iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%). and magnesium (2.1%). These eight elements account for approximately 98.5% of the total mass of the earth's crust. Of course, the earth's crust is only the outer portion of the earth. Future research will tell us about the composition of the mantle and core.

Coppied from a good chemistry web site.

Julian
 

[WozzA]

Save them... put them up on your shelf...  you may be famous one day...   

[bsa-bill]

The most abundant element in the universe is hydrogen, which makes up about 3/4 of all matter! Helium makes up most of the remaining 25%. Oxygen is the third most abundant element in the universe.

Q what is the most common element on Earth

The question related to Earth however and they were wrong also according to Wikipedea

Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal,

not that it is at all possible that I didn't hear the word "metal"

We could start an element  thread

[Angus]

So the general view is to keep them if I want another dust gathering ornament (sorry don?t smoke so they won?t become ash trays) and that they should never see the inside of an engine again.
So will put them in a box at the very back of the roof space in the garage to become long forgotten. Then those that mentioned an emergency will also be satisfied, although I will probably forget they are there.
PS enjoyed the other banter 

[muskrat]

 I turn junk parts into trophys for the next bike show. Split'em in half makes 4.
Hate to think of the poor bloke in 40 years time that finds them to get his 100 year old A10 going.
Cheers