piston reset tool

Fill the holder up with some play dough and really pack it in. Peel it out to confirm the holder itself is not causing the problem. You could also use white glue and peel it out once it's set. It may be the metal was too soft and over time has become dome shaped.

The top of the piston dome shaped? Some Wenmac pistons had dome shaped heads.

Thank you for all of your replies. I was down at my LHS buying some more fuel last Friday, and I happened talk about the piston resetting. The older guy ringing me up said he has an employee who can do it and has been doing it for years. He offered to reset all of mine for free so I went home and grabbed them and brought them in. They said the holder likely got knocked out of shape and sometimes the holders are just machined wrong so they don't use the holders, they place the piston on a thick sheet of plate glass and then tap and spin. It took him 3-5 minutes to do each piston with small taps. They also repair model engines there and other model stuff, nice little place, its a shame these kinds of stores are disappearing.

This seems like a nice site, I would join but I don't work with these engines enough anymore and are only fixing them up to give to my 12 year old grandson who loves lawnmowers, weed whips and chainsaws just because they have engines.

Cheers, Ken

11592_KW wrote:Thank you for all of your replies. I was down at my LHS buying some more fuel last Friday, and I happened talk about the piston resetting. The older guy ringing me up said he has an employee who can do it and has been doing it for years. He offered to reset all of mine for free so I went home and grabbed them and brought them in. They said the holder likely got knocked out of shape and sometimes the holders are just machined wrong so they don't use the holders, they place the piston on a thick sheet of plate glass and then tap and spin. It took him 3-5 minutes to do each piston with small taps. They also repair model engines there and other model stuff, nice little place, its a shame these kinds of stores are disappearing.

This seems like a nice site, I would join but I don't work with these engines enough anymore and are only fixing them up to give to my 12 year old grandson who loves lawnmowers, weed whips and chainsaws just because they have engines.

Cheers, Ken

Thats too bad,you would most likely enjoy being a member here,I sure do.
Thats my kind of LHS we need 1 of those around here

It was nice hearing from you, Have a happy nre year

Any one having problems using the reset tool should check the holder to see if it is made properly. There should be a raised ‘peg’ approx ¼ in dia in the center to support the piston directly under the ball socket only. Some holders have a flat bottom bore and worse yet have a small radius at the edge which will tend to deform the piston. Best not to use those.
al

I have yet to successfully reset a piston and have ruined several including both of my Black Widows. I'm very careful, patient and light handed on a hard stable surface (a Pontiac front brake rotor on a concrete floor), and rotate frequently. I wouldn't be able to use flat glass as some of mine have a nib in the center of the top of the piston. Maybe it's my tool. I'm about tired of trying, though some new ones have more slop than I like. I'll inspect it closer and maybe try one more time. It looks exactly like the picture above.

I've been using one of the cheap reset tools, worked great on a couple of pistons, then the other day the rod piece closed up on the conrod of the piston I was using it on, trying to remove it I managed to pull the conrod completely out of the piston! The moral? never buy cheap tools!

Wilf