tony27 Posted August 17, 2009 Report Share Posted August 17, 2009 (edited) I'm planning on giving my Jarvis a well earned freshen up in the near future & was wondering what peoples opinion of the sealed crankshaft bearings are regarding if their life is any better than the older non-sealed type Edited August 20, 2009 by tony27 Quote Link to comment Share on other sites More sharing options...
copemech Posted August 18, 2009 Report Share Posted August 18, 2009 I'm planning on giving my Jarvis a well earned freshen up in the near future & was wondering what peoples opinion of the sealed crankshaft bearings are regarding if their life is any better than the older non-sealed type Never heard any problems with them, might be better overall, of course the big problem to the standard bearings is keeping crap out of them. I think Neo found a lot of different bearings that will work, all your pick!!!!! Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 18, 2009 Author Report Share Posted August 18, 2009 (edited) Okay Neo time for your input, how are the trick nachis going? Had a talk with SKF dealer here & they don't list the 6206 2RS1 ETN9 C4/GJN as being in the country but the specs they quoted sounded exactly as I would expect would be needed Edited August 22, 2009 by tony27 Quote Link to comment Share on other sites More sharing options...
copemech Posted August 19, 2009 Report Share Posted August 19, 2009 The sealed bearings in the air cooled electric motors that drive the compressors at my shop now have over 20,000 hours on them. Maybe those things doo work? Quote Link to comment Share on other sites More sharing options...
b40rt Posted August 19, 2009 Report Share Posted August 19, 2009 The sealed bearings in the air cooled electric motors that drive the compressors at my shop now have over 20,000 hours on them. Maybe those things doo work? Yeeh, but compressors run out of puff on long climbs. Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 20, 2009 Author Report Share Posted August 20, 2009 Bearings,seals & gaskets are on their way 1 other little thing I'd like some advise on. When I lean the bike to the right on a workstand & turn the rear wheel it feels like it's trying to select a gear which goes away when put back flat so I'm expecting to have some wear in the gearbox somewhere. Does anyone have an idea of the correct amount of clearance between the selector forks & selector ie how much sideplay is acceptable. Otherwise my other thought on possible cause is the bronze bushes/bearings in 1 of the gears has excessive clearance/wear allowing it to tip Any thoughts? Quote Link to comment Share on other sites More sharing options...
neo Posted August 20, 2009 Report Share Posted August 20, 2009 (edited) Sorry for late reply Gents. I'm pleased to say that the Nachi's are still going strong. Make sure you get the high temp (140C) seal ones Nachi Quest. Best of balance. Neo Edited August 20, 2009 by Neo Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 22, 2009 Author Report Share Posted August 22, 2009 Good to here they're still going strong Neo, I ended up ordering the standard late model 1's from the UK, SKF # 6206 2RS1 ETN9 C4/GJN Specs say normal NBR seals & a polyurea thickened grease rated -30 to +150C so hopefully they'll last, heat not so much the problem as water because I ride a lot in creeks esp when trail riding & we all know that shercos are completely waterproof Quote Link to comment Share on other sites More sharing options...
neo Posted August 27, 2009 Report Share Posted August 27, 2009 Hey Tony, You know the SKF website and the Sherco parts book are enough to drive you around twist I assume the bearing you got are rubber sealed both sides?.....because that part number "2RS1" are sealed on only one side And the "ETN9" is different bearing altogether And the only bearing SKF do that seals on both side is the "2Z"....... Can anyone shead some light on this? Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
trialsnutterman Posted August 27, 2009 Report Share Posted August 27, 2009 Have a look here it shows the actual bearing and the meaning of the part codes. I was told the Sherco bearings are especially filled with oil not grease, but I'm not 100% sure of this, I've taken a old one apart and there was no grease in that just oil but it is possible it had just washed away over time. Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 28, 2009 Author Report Share Posted August 28, 2009 Neo I've got the SKF catalogue at work as well, in their codes RS1 is single NBR seal & 2RS1 is seal both sides. Some of the other manufacturers have their own coding for this such as l for NSK from memory. SKF use Z to denote steel shields which is fine for electric motors or skateboard wheels. I seem to remember reading somewhere that beta use these in their motors Quick explaination of the full code for the bearing is 6206 = bearing size 2RS1 = 2 steel backed rubber seals ETN9 = polyamide cage C4 = greater internal clearance- higher number is more clearance GJN = polyurea thickened grease In general the codes can be added together to give the specs of bearing you need The older type bearing code was 6206 ETN9 C3 from memory which will give you an example of how this works Trialsnutterman this is who I got the bearings from, they've been very helpful & parts get here quicker than they would from Australia which is where our bikes now come in via. When I asked SKF about the bearings they confirmed the specs matched what is on the page but said they aren't stocked in New Zealand & they didn't have a price although they would have investigated further if I wanted to wait Quote Link to comment Share on other sites More sharing options...
neo Posted August 28, 2009 Report Share Posted August 28, 2009 Hi Tony, Thanks for the information on this. Interest how these are C4 rather than C3 ....is this something to do with the fact they grease filled? Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 28, 2009 Author Report Share Posted August 28, 2009 I don't think its anything to do with being grease filled but more to do thermal expansion & the possibilty thats what is leading to the short life span they can have I've got my engine apart at the moment & found the transfer ports have a black film in them the same as the bearings often do when they fail, wish I knew the reason for that Quote Link to comment Share on other sites More sharing options...
copemech Posted August 29, 2009 Report Share Posted August 29, 2009 I don't think its anything to do with being grease filled but more to do thermal expansion & the possibilty thats what is leading to the short life span they can haveI've got my engine apart at the moment & found the transfer ports have a black film in them the same as the bearings often do when they fail, wish I knew the reason for that I presume the old bearings are the "open" style? Might suggest a breakdown of the lube oil under high temps. These bearings are not well cooled in these motors or application. What oil are you using? Quote Link to comment Share on other sites More sharing options...
tony27 Posted August 29, 2009 Author Report Share Posted August 29, 2009 They were the older open 6206 ETN9 C3s, the sealed type hadn't come out as a fix when I last replaced them Like you say they aren't exactly overcooled in the cases but I'd expect to see wear in other places in the engine & quite a bit of carbon on the piston crown & head but they're fairly clean. Seem to remember the blackness as being something mentioned in earlier postings with bultacos suffering particularly badly in the 70s, thought back then was carbon comtamination so you could be on to something with oil film breakdown I run motorex powercross at roughly 70:1, is meant to be a very good oil Quote Link to comment Share on other sites More sharing options...
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