S3 Race Custom Modified EC250 Complete Rebuild

[Jakobi]

Just a few random shots

[GMP]

What do you mean by "sealed bearings seemed to pass 2 stroke oil through them"? That sounds very odd to me. Sealed should be sealed. Honestly I never had one of these in my hand, what is the seal material? How hot did you get the bearing in the repeated case warmings?

I'm not a fan of these, they were born from preliminary research in DI and low oil mix ratios (emmissions). My '12 is supposed to have them as well. Funny though, since new my ignition side has the extra radial play that is indicative of the NJ roller bearing, feels like my '07. So, it was either not built to current spec and does use the open roller(fine with me) or is on the verge of going boom. Since it runs well with no excessive noise I suspect the former is true. '12s are a grab bag of leftover parts.

[Jakobi]

Well I assume the oil passed through. The mains are SKF 2RS. Rubber seal both side. Maybe the oil wasn't, but when using a small syringe and pushing some oil down through the case holes it flowed out both sides of the bearing space.

One of the bearings had a short stint in the oven at 100C which is a bit hotter than the bearings should be, and I was worried that it might have cooked the grease out but it appears to be ok. After that I made sure the mains were the last bearing to be put in the cases. They were one of the easier ones to drop in anyway. Of course this was the first bearing I attempted to drop in and sat sideways. I had to use the heat to get it to fall back out. No way I could pull it out by hand without it and no way I was going to force it in.

After the whole lot was done and cooled down and lubed, I used an awl and picked the inner lip up a bit just to check that there was still grease in there. All is well. I guess the seal might be enough to hold grease in, but not enough to stop oil entering. I guess the same way that water still manages to make its way into sealed bearings in wheels etc.

I know you're not a fan of these Glenn, and I'm not really either, but for me being my first time in here, and not knowing the front from the back it was just easier to purchase a complete bearing kit. One less thing to worry about. I also managed to get 260hrs out of these without any issue, so I consider that to be a postive thing. They've always had a little radial play as well when grabbing the flywheel. Not much, but a bit. It freaked me out after my last top end 110hrs ago. It hasn't got any worse and apparently the C3 bearings will have a little radial play to them as well.

[GMP]

In most cases they have been fine. The few reported failures I have read about have been due to seal failure, and subsequent loss of grease due to being spun out by centrifugal force. An open main bearing is lubricated by separated oil dripping through the hole in the transfer port area of the cases. The presence of the seal, even if it is compromised, limits this.

Hope it works out. IMO, its just one more thing to fail that is not needed in a racing engine. My local supplier does a lot of hybrid ceramics, thats what I'll likely put in mine when its time.

Next time, use dry ice to freeze the bearings, they will drop in a lot easier. Your freezer does not give you a high enough temp differential for an easy shrink fit. If by chance you can get LN2, its a snap.

[Jakobi]

Now I'm crazy paranoid its going to blow up.

[Jakobi]

So I picked the seals out of the mains I pulled out, and there's no grease left in them at all. Do you think it would be wise of me to remove the inward facing seals? I can't get the outer ones unless if I pull the bearings out again.

Thoughts? Will I get enough splash lub from the crank side to keep them happy? Does this increase the risk of shagging my main bearings if my bike goes for a swim and takes on a heap of water?

[GMP]

Like I said, the bearings are lubed by the separated oil running down the holes in the cases. There it is trapped and picked up and slung through the bearings. Bad idea pulling inside seal off. Either commit to use as is or get rid of them and run open bearings.

No grease in old bearings should tell you something, shouldn't it?

[Jakobi]

So pop them both back out and remove both seals.. or run as is..

like you said.. dry old ones says something.. really has been one of those days. I'm off to bed to battle with my head.

[Jiikoo811]

Originally Posted by Jakobi

So I picked the seals out of the mains I pulled out, and there's no grease left in them at all. Do you think it would be wise of me to remove the inward facing seals? I can't get the outer ones unless if I pull the bearings out again.

Thoughts? Will I get enough splash lub from the crank side to keep them happy? Does this increase the risk of shagging my main bearings if my bike goes for a swim and takes on a heap of water?

When i rebuild mine, i take of both seals from main bearings. Clutchside bearing was with seal from factory
And fail badly...even broke a case. It going now 200hrs without any seals in main bearings and no freeplay when crab flywheel or clutchside either
Someone say it have to take both seals of, it makes sense because then bearing can breathe oil,gas air mixture all time.
Sorry my english...not perfect... I am finish

I think if seal fail grease go out but oil,gas,air mixture cant lubed it well because seals..even broken ones

I can post later today couple pics of cracked case and fail clutch side main...It was used bike so cant say hom much hrs but i guess not more than 200...it was 2 years old 2009 bike when i rebuild it.
Sent from Razr MAXX

[Jakobi]

Originally Posted by Jiikoo811

When i rebuild mine, i take of both seals from main bearings. Clutchside bearing was with seal from factory
And fail badly...even broke a case. It going now 200hrs without any seals in main bearings and no freeplay when crab flywheel or clutchside either
Someone say it have to take both seals of, it makes sense because then bearing can breathe oil,gas air mixture all time.
Sorry my english...not perfect... I am finish
Sent from Razr MAXX

It makes sense. Just kicking myself for not doing it sooner. Hopefully I'll be able to use a torch arond the mains and have them drop out without too much fuss.. otherwise.. back in the oven and probably have to do most of them again. You live and you learn. Better now than later.