Power Valve Bearings - What Type?

[JP4]

I've searched and it seems there are lots of different ideas on the type of bearings to use in the power valve - open, 1-side metal shielded (Z), 2-side metal shield (ZZ), 1-side rubber seal (RS), 2-side rubber seal (2RS), combination of each. Some think the bearings need to be lubed from the oil in the exhaust gases, other say they need to be sealed to keep the spooge out. I've no idea what's best.

The stock ones are sealed on both sides, looks like rubber seal to me. Not sure if it's some type of high-temp rubber though.

The SKF 608-2RS and 6000-2RS replacements I picked-up use NBR rubber for the seals and are rated to 100C temperature, and up to 120C for brief periods. The grease in the bearings is rated up to 110C (6000 bearing) and 140C (608 bearing). Rings and balls are rated to 120C. Will these be ok?

Anybody have an idea of how hot it is where the bearings are located?

Anybody used 2RS bearings without issue?

[stian]

Originally Posted by JP4

I've searched and it seems there are lots of different ideas on the type of bearings to use in the power valve - open, 1-side metal shielded (Z), 2-side metal shield (ZZ), 1-side rubber seal (RS), 2-side rubber seal (2RS), combination of each. Some think the bearings need to be lubed from the oil in the exhaust gases, other say they need to be sealed to keep the spooge out. I've no idea what's best.

The stock ones are sealed on both sides, looks like rubber seal to me. Not sure if it's some type of high-temp rubber though.

The SKF 608-2RS and 6000-2RS replacements I picked-up use NBR rubber for the seals and are rated to 100C temperature, and up to 120C for brief periods. The grease in the bearings is rated up to 110C (6000 bearing) and 140C (608 bearing). Rings and balls are rated to 120C. Will these be ok?

Anybody have an idea of how hot it is where the bearings are located?

Anybody used 2RS bearings without issue?

I have the same question. My local shop got very cheap 6000 2RS bearing and a 608ZZ bearing, we are talking less then 10dollars. Going to try it out, cant be worse I guess.

[JP4]

After cleaning up the old bearings I realized they are in fact shielded (ZZ) and not rubber sided (2RS). The bearing supplier exchanged the 2RS bearings that I originally purchased for ZZ ones.

[motopsycho87]

I did a rebuild over a year ago using unshielded bearings. After seeing the state of the old metal shield bearings, and how oil/soot had gotten in and dried, I figured non sealed would have a better chance of staying wet. No problems so far, and still very clean when I last adjusted the PV.