Low Compression Heat Treating Piston Rings

[pwilber]

I picked up a 1996 Seadoo SPX cheap. The ski runs, but starts hard, and idles poorly. I have rebuilt the carbs, replaced the fuel hoses. When I check the cylinder compression it was 70 - 70 in each cylinder. I removed the head, and pulled the jugs. The pistons look ok, and the cylinder walls look pretty good also.

I used to own an old free air snowmobile growing up, and we used to heat treat the rings when the compression would got lower. It involved placing the rings on an electric element from a hot plate stove top with a spacer placed in the gap to widen it (a metal nut).

The hot plate heats up to about 900 degrees and the ring stays on the element for about 15 minutes. The element is turned off and the ring is allowed to cool to room temperature. Rings are reinstalled and "boom" compression would go back up to 150.

I'm trying this right now with the seadoo. If you have ever heard of this trick, let me know.

I have little money in the ski, I just wanted to see if it would work.

 

[Dr Honda]

Well....

You don't want rings to be hard. They are a seal, and most of the time the are made from iron with ground edge. The rings don't loos compression because they loose their "Spring"... they loose compression because they loose their sharp edge.

Rings are cheap. If the pistons are good, and the cyl's are OK... give them a quick hone (to rough up the surface) and slap in a new set of rings. BUT... I can guarantee that the piston clearance is out of spec, if the rings are that warn. The new found power may shatter the engine.

 

[pwilber]

I reinstalled the rings after increasing the ring gap. I'm not advocating this as an approved practice, but I now have 125 -130 psi compression (previous compression 70). I'll monitor and update the progress of this experiment. So far it has started easy and is idling much better.

 

[Spx]

Hmm very interesting

 

[SabrToothSqrl]

indeed....

 

[Dr Honda]

Hmm very interesting

indeed....

Not really.

1) it's a band-aid.

2) hard rings will eat the cyl walls (that's why they stopped putting chromium in them)

3) it will cost you more in time, effort, and gaskets than just paying the $20 for new rings. (Still a band-aid, but it's the proper way to do it)

4) The guy has 2 posts to his name... he didn't show us his method... he didn't show us any proof of before or after... so I don't think I would trust any of this.

5) He says "I reinstalled the rings after increasing the ring gap."... so that tells me ha has no Idea of what he's talking about, since the gap is measured with the ring in the cyl, and making it bigger would cause more leak-down.



As I said before... the rings work because of a sharp edge, and not because they have a heavy spring force.

 

[SabrToothSqrl]

http://www.youtube.com/watch?v=Uhm-NTzc4rU

I agree that this will compromise reliability, and if it works, I would be surprised to see it last a season or two... but time will tell.