Piston pin surface finish?
Posted May 02, 2002 - 04:23 PM
I was not that concerned about it until I was talking with a machinist (who works primarily on car engines)about turning down some swingarm bushings and his concern for getting a polished finish to keep the bushing from tearing up the bearings. Of course I did not think of the piston pin while talking with him so I did not get a chance to discuss this specific application with him.
Has anyone replaced their piston pin and noticed this dull finish? Or did Yamaha sell me a defective unpolished part that could cause trouble down the road?
Posted May 02, 2002 - 07:11 PM
I, too, would be very reluctant to install an unpolished wrist pin. It is, after all, a critical, hard-to-lubricate, extreme load-bearing component. If the surface has been treated (nitrided?), that MAY explain it. But you would be wise to find out definitively.
How 'bout it? Many of you have also done WR top ends...was your wrist pin like Mike's? SFO?
Posted May 02, 2002 - 10:10 PM
Posted May 04, 2002 - 06:25 AM
Now I can ride with confidence that I won't have one of those expensive four-stroke seizures. Thanks again; Moto-Mike
Posted May 04, 2002 - 06:35 PM
I replaced it with a wiseco pin on my 97mm bore which I taper bored the id @7 degrees to pull some heft out of it.
Even after ball honing the small end it galled again.
Can you see if it is a new part#?
Run the pin by a shop with a profilometer and check the rms.
[ May 05, 2002: Message edited by: SFO ]