TheSamba.com :: View topic

Sat Sep 06, 2014 3:11 pm

I have them at 377.3 grams, I know there are some obvious risks when re using pistons, but to me, these seem nice enough. Probably no more of a gamble than AAs right? #'s 3 and 4 had a little heat damage, I took off the edges and scoring with some emery cloth, they measured OK. Don't remember what the "envelope" was but is was in spec, a little on the worn side.

Anybody else re using pistons these days? Or am I the only one? :lol:

Sat Sep 06, 2014 4:01 pm

Ring grooves worn? Pin fit? AAs are not much of a gamble these days it seems...

Sat Sep 06, 2014 6:01 pm

AAs are a good gamble. Also, there is no gamble on used pistons as long as they spec out well. They've already withstood the test of time. Now you just need to verify that they can again. What Scott mentioned; check your ring side play, ring gaps on whatever new set you purchase, piston pin O.D. On the ends and in the center, piston-to-liner clearance, and liner out-of-round and liner runout. If all is within spec, run them.

Sat Sep 06, 2014 6:18 pm

I've rebuilt many motors with reusing the stock pistons as long as they spec out. For a stock rebuild, I see no reason not to.
Just make sure the ring glands are super clean and not collapsed.
Never had a failure yet when using stock used pistons.

Sun Sep 07, 2014 4:23 am

One of the areas to look at is the cylinders. The of top of the cylinder is where they will show wear. As soon as you start to hone the cylinder, a spot will apear where the top ring reached the top of it's stroke. I hone the cylinders first, then measure and match up the pistons to the cylinders as best I can. I also increase the ring gap about .002" to .003" from what is normal. You don't want a tight ring when you are reusing pistons and cylinders.

Sun Sep 07, 2014 12:38 pm

bugguy076 wrote: One of the areas to look at is the cylinders. The of top of the cylinder is where they will show wear. As soon as you start to hone the cylinder, a spot will apear where the top ring reached the top of it's stroke. I hone the cylinders first, then measure and match up the pistons to the cylinders as best I can. I also increase the ring gap about .002" to .003" from what is normal. You don't want a tight ring when you are reusing pistons and cylinders.

Thanks I will consider that. I did hone the cylinders first and they had noticeable wear. I will post pictures of those too.