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Post by rcq92130 on Oct 30, 2014 19:32:31 GMT -5
Thinking the reason the last BBK install failed (after only 5 or 6 hundred mi!) is the piston was in upside down. Here is a photo of the piston, with the sizes of the indents:  During the first install - no directions included in kit - I thought ("ASSumed") the arrow etched onto the face of the piston pointed toward the intake side, and installed it with the arrow pointing "up" when installed. But measuring the valve indents, the one next to the etched "60" is larger --- so, probable for the intake valve ... right? Or is that wrong .........  ? |
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Post by rcq92130 on Oct 30, 2014 19:41:33 GMT -5
BTW, someone asked that I measure the actual size of the piston to see if "60mm" is true or a lie.
At the top (above the #1 ring) the diameter is 2.342in (that's 59 1/2 mm)
At the skirt the diameter is 2.365 in. (that's 60mm)
I don't have a proper micrometer to measure the inside bors of the cylinder liner, and with the mic. I have am getting measurements SMALLER than the piston skirt (2.362 at the top, 2.360 at the bottom), which is obviously wrong since the piston slides easily inside the liner (brfore the rings were installed, of course).
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Post by alleyoop on Oct 30, 2014 20:00:59 GMT -5
Thinking the reason the last BBK install failed (after only 5 or 6 hundred mi!) is the piston was in upside down. Here is a photo of the piston, with the sizes of the indents: During the first install - no directions included in kit - I thought ("ASSumed") the arrow etched onto the face of the piston pointed toward the intake side, and installed it with the arrow pointing "up" when installed. But measuring the valve indents, the one next to the etched "60" is larger --- so, probable for the intake valve ... right? Or is that wrong ......... ? Yes, the bigger indent is for the INTAKE so that goes up, if you installed it with the smaller indent up then you would damage the piston. Alleyoop |
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Post by alleyoop on Oct 30, 2014 20:02:37 GMT -5
The piston are never the size they say they are, they are always smaller, they round them up. Alleyoop Here is my OEM Piston considered a 58  Here is my 62 bbk piston:  |
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Post by rcq92130 on Oct 30, 2014 20:10:36 GMT -5
I wonder if that is the cause of the early failure. This is a crappy photo (of the initial BBK install), but you can see the "60" at the BOTTOM (exhaust side), which i guess is WRONG:  There isn't any obvious evidence of valve-to-piston contact, but maybe at high RPM (for me only 7,000) the two WERE contacting, and maybe the valve bent just enough to mess up compression (and performance). No EVIDENCE of that, but if soot then covered over any shiny marks ... Or maybe I'm just grasping at straws. Anyway, it DOES seem i installed the piston upside down. |
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Post by alleyoop on Oct 30, 2014 20:23:52 GMT -5
The scrappy piston the 60 is at the bottom BUT look at the actual indent the one on top is bigger. So you went by the number stamped on the piston and not the size of the valve heads to match the piston indent. And yes you installed it upside down.
Alleyoop
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Post by xyshannen on Oct 30, 2014 21:02:57 GMT -5
Thanks for the confirmation of measurement. That's exactly what I was wanting to know.
Good luck this time round.
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..BAD TO THE BONE..
