pianotop piston ID??

[2002Targa]

Greetings all,

thanks those that replied about my cam ID question.

These are the pistons that came with the motor, I'm trying to figure the comp for them. This is what's stamped on the top:

Made in Germany

89.47 (with A1 beneath that)

208

M

097

Sp0.045

mm (on top of the piano)

Also, once I tear the motor apart, what do you check on the pistons to see if they're still useable? There's some rust on the cyl walls, so I think it's been sitting for quite a while.

Danke,

TK

[visionaut]

Well the 89.47 is the bore size, indicating they're oversized. Stock bore for the 2002 M10 is 89.0 (1990 cc). Most piano-tops are Mahle 9.5:1 compression, though some are 9.3:1.

Not sure what the other numbers are...

HTH,

[02Les]

http://www.bmw2002faq.com/content/view/46/32/

The faq Piston guide.

[TobyB]

As to reuse,

check the skirts for scuffing (clean that rust off the bores first, or it's a foregone conclusion!)

and then measure them-

stock is 88.97, 1st is 89.22, 2nd is 89.47, which is what you have.

Then check the ring lands- there should be very little gap between the ring and the piston.

I've never found a set of used pistons that I felt good about reusing...

fwiw,

t