Crank-seal question

[cheese]

Ok so I replaced my seal and my bike started to blow smoke again really badly, so I just stripped it wdown adn I think I put it in the wrong way round, but I think that the shop where i had it done about a year ago did the same thing......

So Iwas going to ask, with the crank seal, teh spring should face the oil side?

Lucky the crank seal is on teh outside on a RM.

[Brian d marge]

Piece of Proverbial to do the seals , yup you are right , Though what concerns me is that they are gone again... all okay down stair , crank inline?? damage to crankase ??
or more likely dirt or water getting in ???

for the cost of em and the ease of doing them I would just swap em out

Stephen

( on a cr that is !!!!)

[Motu]

If the crank seal is on the outside of the main bearing then it is isolated from the gearox oil and lubricated by the fuel mixture,the lip and spring side needs to face towards the bearing.If the seal is on the inside of the bearing it is lubricated by the gearbox oil,and the seal needs to stop oil entering into the crankcase.

[cheese]

yeah the seal had the spring part (is that called the cup??) facing the bearing and had the flat part to the gearbox oil. I think that it was in backwards.

Should I take some photos?

[Motu]

If the oil seal is outboard of the bearing then that is the correct way round.

[cheese]

Ok so I found this pic of the set up.

Its the seal (number 14) on the left hand side. So from what I can tell from the pic (not that its very clear at all!!) its got the spring facing the bearing.

Maybe the seal I just used was a shit one? the old one lasted a year or so. But it wore badly cause there was some build up on the primary gear (number 16) that I think damaged the seal. I sanded it down with some 1000 wet and dry and it was working fine.

Is there any other place that the gearbox oil can find its was through? the only other place I can think of is the gasket that runs through the middle of the crank! but that is pretty new.

[Motu]

So for the 3rd time - yes,the spring side should face the bearing.

[Ixion]

Yes. That is the classic setup. Spring bit of seal faces inward toward the conrod. So what you see behind the primary drive pinion is just the plain back of the seal.

What is the considtion of the crank journal teh seal runs on? Fitting crankcae seals 9any seals actually) takes some care. Use tape or a sleeve to ease the seal past any keyways, threads etc on the outer portion of the shaft. Make sure the seal is installed squaer into its housing - use a spacer to press it home.

[xwhatsit]

So for the 3rd time - yes,the spring side should face the bearing.

Lol, it took me a while to work out what you meant as well. Don't get upset.

[cheese]

yeah the primary gear was a bit worn so I sanded it down with some 1000grit wet/dry and it feels a hell of alot better, but yeah maybe I had the seal in not quite square or something. I'll take a great big fuck off socket this time to hammer it in a bit.

Think I might recondition it too while I'm at it.

[cheese]

Oh and thanks Motu, sorry for asking 15 times.

[Motu]

Lol, it took me a while to work out what you meant as well. Don't get upset.

I don't get upset,just a little exasperated.The basics of seals is to know what you are sealing from what.There is some confusion with 2 strokes I have only just figured out myself,when I was trying to see which bearing has failed in my DT230.Early 2 strokes,(the ones I have worked on) say pre 1990 mostly had their drive side bearing running in gearbox oil,the seal was inboard and stopped oil getting in the crankcase.Modern 2 strokes have both main bearings lubed by the fuel mixture,and so the seal is reversed to seal the crankcase.There are double lip seals and complete double seals on one body.

I have little experiance on modern 2 strokes,the only water cooled smokers I've done engine rebuilds on are the first watercooled KDX200's - so I'm looking forward to getting inside my DT230.

[barty5]

the other thought if you do this (full stip down ) is the bearings you put in get sealed ones pop out the seals flush out the grease then put but back the seal in one side this will allow lubrication to the bearing but help keep out any gear box oil that may get past the lip seal.