ETZ 125 engine bearings and seals

[Jay Bee]

Following on from my last post, I've trawled through the web sites of various European parts suppliers, to see what's available.

I see that a number of these specify C3 grade bearings; although I am familiar with their use as crankshaft bearings in various bike engines I've overhauled in the past , I don't recall using any for gearbox, etc.
All the old bearings removed from my engine are marked "DKF DDR", and I believe are original to the bike, but there is no trace of C3, or any other int. clearance markings.
Should I use normal clearance bearings throughout, C3 for crank main bearings/normal for the rest, or ???

Also on offer from some suppliers are "double lip" (presumably seal lip + dust seal) crank seals in viton. Does anyone know if viton or dust lip features offer any worthwhile advantage over standard seals in this application?
My old crank seals are single lip and light green in colour (well, one side, anyway + black the other) - and rock hard !
They are similar in appearance to Supa Five crank seals (according to my hazy memory of replacing them 30+ years ago) and leads me to believe they are OE seals, but I was surprised to find that the r.h./alternator side seal appears to me to be fitted the wrong way round ? (open/"spring" side facing the alternator)...........

What spec. seals and bearings have others used ?

[Agronski]

Can't speak much about bearings - my '76 TS150 still has the DDR bearings in, and I too noticed no "C3" stamp on them when I changed the oil seals recently. But my bearings are still sound, so didn't have to worry.

However, this story might give you some info (not to mention a laugh) http://www.realclassic.co.uk/mz06072600.html
Short answer: any good 6306 C3-style bearings should do fine.

As for seals: Viton is supposedly more long-lasting than Nitrile, but any modern double-lip oil seal of the right dimensions should do fine. If the ETZ is anything like the TS, the seals ride in holders that also have paper gaskets surrounding. As long as the seals are well-greased before you install them (use the best moly stuff you can get, it's best for high-pressure work) then they'll last as long as you want them to. In the grim days of in-board seals (i.e. *behind* the bearings, with the seals closest to the crankshaft) the seals may be been installed spring-side out - a bit hard to see, but you can just about make it out on this picture: http://www.gaborsmzladen.de/pic_show.ph ... 70.806.jpg - later, they moved the bearings in-board to keep them lubricated with petroil mix. The lip/spring faces towards the point of maximum pressure, so the seals should face spring-side towards the crank. That's how they are on my TS, and since I changed the old seals, she now purrs like a kitten.

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