ashesman

I am going to put the sealed bearings in as an experiment. I am confident they will be OK and it is interesting to me to see how they go. Unfortunately I was sent the wrong crank seals so waiting for new ones of them before I can assemble the engine. I will report back here on how they go but I suspect (and hope) this thread will be well gone before I need to do those bearings again (although it was only two years ago I did them last time!). No alcohol in our fuel as far as I know...

I had a crash and hit the side of the fork at the seal. It made the fork tube slightly (actually quite a lot) oval at the seal. I had to press it out carefully and managed to get it back to round within a few hundredths. Most likely you just need to realign your forks. On a side note, IMO, I personally think seal mates or any other form of thing (like a goggle tear off or credit card) that you put in and around the lip of the seal is a bad idea. Firstly you risk pushing crud into the fork, secondly you risk damaging the soft lip on the seals. Generally if fork seals leak they need replacing. There is the odd time some grit gets in them but they should be cleaned by disassembly, not poking something into the for seal. You can get a lot of hours out of fork seals, when they leak, replace them and then get lots more trouble free hours. Never leave dirt to go dry and hard on your forks as most wiper seals are not strong enough to scrape it off.

Thanks everyone for your feedback. So, I am still on the fence about what to do! The easy option is to pull the seals out and just put the bearings in and carry on... But, I quite like the option of running sealed bearings as an experiment but it seems that the bikes running them must still be too new to be being pulled apart. I cant find any factual information on the number of hours people are getting out of sealed bearings. I also cant find any factual information about the bearings being fitted to new Beta engines. I did some research in SKF documentation and they have all the right seals, grease, cage and characteristics to work well sealed. They are high performance SKF explorer bearings. The seals in them are pretty clever looking and sit quite deep. Sealed bearings can do thousands or more of hours in industrial applications so should be OK. It is not the bearings I am worried about, more that the side seals get enough lubrication. Funny how little decisions like these can really bring you to a halt!

Hi all, I have a 2008 Rev 3 270. Engine is stripped down for a rebuild. I purchased new main genuine Beta main bearings and they come with seals in them (SKF 6206-2RS1TN9/C4GJN). The supplier says that is how they come in the new bikes now? Can anyone please give their advice if I should leave them in or take them out? I noticed the photos in the 09 service manual show metal shields fitted to the main bearings! The seals look a bit special unlike the normal flat seal fitted to normal bearings. Leaving the seals in bearings: - Reduced crank case volume - Potential longer life (if they survive) - Allows leaner oil mix - Potential for either limited side seal lubrication OR - Potential for build up of oil in the side seal area that may spill into crankcase if the bike goes upside down For taking them out: - How I have seen it in most engines - Ensures airflow/lubricant flow as designed by the manufacturer (assuming originally fitted without seals). - Seals may not be correctly rated for oil/fuel - Bearings may not have correct temperature rated lubricant in them - Pressure pulsations in crank case damaging seals or popping them out or pumping lubricant in/out. Does anyone have experience rebuilding these engines that could offer advice? I am actually not worried about the bearings surviving with the seals left in but the effects of limiting air flow/lubricant to the side seals. My first main bears did 300 hours and got slightly grumbly, second set did 80 hours and got so hot they broke a cage and seized (although I may know why but want to stay focussed on this topic!). Any help appreciated Ashley