Pro-X Pistons for 787 question

[WVGreenhorn]

I've been told that the Pro-X pistons for the 787 have a different ring location than the OEM pistons. The OEM pistons have the top ring flush with the top of the piston and I was told the Pro-X have them spaced lower like a conventional piston.

First, can anybody confirm this? And if true, what effect would this have on compression, port timing, etc.?

I've ran the Pro-X pistons in a lot of ATV's and dirt bikes and have had excellent service from them, just want to make sure thay are the right choice for this motor also.

The Greenhorn

 

[WVGreenhorn]

Anybody build with the Pro-X pistons??? Anybody???

 

[Dr Honda]

I hate to see things go unanswered... but I can't say that I've ever used them.

If, they moved the ring down, it wont really effect the port timing since it's the piston crown that is setting the timing. Yes, it's true that the ring is the sealing point, but when the engine is warm, the clearance between the piston and the cyl wall is very tight, and at 7000 RPM, there will be no dynamic difference.

Personally, I think I like the idea of a ring that is moved down. It may help protect it a little better, and give it a little more support. Not that the OE pistons have a problem with that, but I have seen a few times were a lean run allows the ring to break free, and in turn, causes more damage. If there was a little more meat at the crown, it may still melt, but there may not be a catastrophic failure of the ring.

I have a 720 sitting on the floor of my shop. I may throw a set of pro-x pistons in it, just to check them out.

 

[WVGreenhorn]

Thanks Doc, guess the Pro-X pistons just aren't as popular with the watercraft market as thay are with dirt bikes and atvs. Think I'll give them a try.

 

[Chester]

Go ahead and use then. Pro-X are very popular with PWC's. I use them all of the time. The top ring is not in a different location, it's just a different type of ring. Sea-Doo uses a Dykes ring (L shaped) where-as Pro-X are just standard rings.
http://www.mecoa.com/faq/rings/ringtypes.htm
Also, Pro-X pistons are made by a company in Japan called ART. ART makes the OEM pistons for Kawasaki and Yamaha and therefore, are of the same quality.
The only pistons that I use in a customers engine are OEM or Pro-X.

Chester

 

[WVGreenhorn]

Chester,

Thanks for the info and the vote of confidence!! Pro-X it is!!

The Greenhorn