Labyrinth seal failure symptoms

[1601pete]

Evening all

Can anyone indicate what the symptoms are if a labyrinth seal fails please.

Thanks

[steeley]

Apr 25, 2021 21:59:22 GMT 1 1601pete said:

Evening all

Can anyone indicate what the symptoms are if a labyrinth seal fails please.

Thanks

Hmmm , what are you talking about and what machine .

[1601pete]

The seal on the crank shaft in between a twin cylinder two stroke engine.

[steeley]

What machine . LC /YPVS / RGV / KR1S /TZR / GT /RD /any clue . No

[chrisg]

I've not heard of them failing. There usually replaced when the crank is refurbished. Why do you ask? Low down on power?

[1601pete]

Got issues on my 500lc. Can’t get a consistent air fuel ratio on the dyno on the front cylinders. Tried everything to eliminate.

[4l04ever]

Could be an air leak...

[tacky1]

Ive never heard of a labyrinth seal failing, Its a non contact seal. Did you do a leakdown test, Did you replace the crank seals, pistons etc, Could be a leaky head gasket, cylinder base gasket, crankcase leak or a crank seal leak, More info needed......;.;

[zed1015]

As above.
Labyrinth seals are non contact and use opposing primary crankcase compression to prevent loss or transference of pressure between cylinders..
They run close to the crank but do not touch so there should be no physical wear unless there has been a previous engine or bearing failure where debris has entered the seal allowing intermediate material to contact the surfaces and increase the clearance which would reduce it's effectiveness.

[steeley]

Years ago i heard of a 350 ypvs running badly and low on power. The chap i know who was looking into it tried all sorts to get to the bottom of it . In the end it was engine out and stripped .The owner had a fresh crank fitted a couple of weeks before and it turned out the new labrinth seal was under size .Once sorted all was well.

[midlifecrisisrd]

Have only heard of one issue

It's basically a resistance. "Seal has a few discs. Some attached to the centre, some to the outer. Relies on the restriction of air having to work it's way through the "labyrinth"

As said only heard of one engine that wouldn't run correctly until it was replaced.

Now whether something else was accidentally fixed at the same time I don't know but it was a reputable builder who had tried everything else

Steve

[1601pete]

Apr 26, 2021 2:32:00 GMT 1 tacky1 said:

Ive never heard of a labyrinth seal failing, Its a non contact seal. Did you do a leakdown test, Did you replace the crank seals, pistons etc, Could be a leaky head gasket, cylinder base gasket, crankcase leak or a crank seal leak, More info needed......;.;

Yeah, have conducted a leak down test which was all good and checked every other possible issue ref air leaks. Have access to spare coils, CDI, stator. All made no difference.

[4l04ever]

Did this issue get resolved?