crankshaft seal lips..

[A100man]

R21 (single lip) or R23 (double lip)?

For my go-ped (a100) Seems like the latter ought to be better but you guys might know why not.
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[stinkwheel]

I've only seen single lip seals used and the engine I'm building now uses single lip.

There again, I always wondered why they don't want a double lip and why they don't use them the other way round because the single lip seals are set to stop stuff blowing out of the crankcase which is creating a vacuum for half the cycle and we don't want air/gearbox oil going in past them.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[WD Forte]

dubbo lips

Yer typical single lips are for one side at ambient pressure while the seal keeps oil/gas/water above that as we all knows right?
As the crankcase on filthy stinking planet destroyin 2 smoke is constantly
alternating betweeen pos to neg pressure as it goes about Satans business,
a double lip seal sounds eminently sensible
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bikers smell of wee

[A100man]

The double was a few pence cheaper anyway.. so..

PS does anyone know if NOK brand was suzuki standard fitment? I guess yes and thus the beauty I removed was 43 years old and still working well enough.
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[jaffa90]

[Raffles]

I rebuilt a Bultaco engine recently and the OE parts were two R21 type seals, installed back to back, on each side.
If fitting single seals, I'd choose R23 type every time.
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A good loser will always be a loser.

[MCN]

Lebo-lumbian songstress, Shakira, insisted that Lips Don't Lie.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[WD Forte]

Loose lips sink ships
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bikers smell of wee