sunny Posted September 5, 2009 Report Share Posted September 5, 2009 Can I use these bearings on the crankshaft? They are the same size but does it matter that they are sealed? I have to heat them to fit them back in to the case. I have started to re assembly the engine that came in the basket case of parts. It appears that almost all of the parts are there except for a few. The other question that I have is if the kickstart assembly looks like it is set up properly? I think I have but this if my first time doing a rebuild. Thanks for the help Sunny Quote Link to comment Share on other sites More sharing options...
gomey68 Posted September 5, 2009 Report Share Posted September 5, 2009 Hi, You can flick the seals out of the bearings as the gas/oil mixture is supposed to lubricate the bearings. I am pretty sure the bearings must be C3 rated as this gives bigger clearances inside the bearings allowing for expansion due to the high heat application. The kickstarter looks OK, I will check an engine I have partially assembled later and let you know. Remember to set the tension on the kick start shaft return spring before you assemble the case halves. Hope that helps,,,and it's correct :-) Quote Link to comment Share on other sites More sharing options...
dave dix Posted September 5, 2009 Report Share Posted September 5, 2009 Hi, nice bearing but not for your crank. You must use open bearings or prise out the seal but those Aren't C3 BEARINGS. C3 have a larger space between the balls allowing for heat expansion, that bearing will seize if it gets a bit too hot Dave Quote Link to comment Share on other sites More sharing options...
john collins Posted September 5, 2009 Report Share Posted September 5, 2009 Your picture looks OK - but as someone else has said make sure you tension K/start spring. Best way is to take off to two K/start gears ie the large one shown and the small ratchet one underneath. Put K/start on shaft and turn shaft until hook of k/start spring is just locating on the stem of shaft ( behind shouldered nut. Then turn the K/start one or one and a quarter turns around and place the ratchet gear onto the shaft as per your photo. Make 100% sure that you have the k/start spacer washer on top of the large k/start gear before you assemble cases. It is the only spacer in the whole of a Bultaco 5 speed set up - but is the one that often gets lost/missed out Flip the plastic seals out of your bearings if you wish to use these - as others have said you should use C3 - but to be honest it is not as critical on this motor as you would think - and while good engineering practice requires them - I have never had a problem with Bultaco motors on normal 6205 - and I have ridden and built literally hundreds of the things. If you can locate C3 at normal price use - if you are on tight budget you will get away with 6205's Quote Link to comment Share on other sites More sharing options...
sunny Posted September 5, 2009 Author Report Share Posted September 5, 2009 Thanks for the advice. The bearings in the photo came with the basket of parts and I assumed they where for the crank due the same size. Where would these best used? I think the crank on the m159 needs 3 bearings. What should I ask for when I go the bearing supply house? C3 bearings but what size? I guess I need a quick tutorial on the language of bearing sizes. Thanks for the input and suggestions. I do have the haynes and clymers manuals, and the bultaco parts book but it is still nice to confirm with the 'experts" It did come with some new old stock stuff Thanks again Sunny Quote Link to comment Share on other sites More sharing options...
pedronicman Posted September 5, 2009 Report Share Posted September 5, 2009 Only use '6205 C3' or higher 'C4' spec bearings in the crank DO NOT use sealed 6205 bearings in the crank as the tolerance is wrong You can use the sealed 6205 2RS (means 2 RUBBER SEALS!) bearing behind the front sprocket in the case on the sleeve gear or if you have a single row bearing in the back of the clutch basket then this is also the same , all bultacos varied in the the bearing in the clutch basket and you may have a deeper double row bearing in the back of the clutch basket which is different and will not fit. Your 159 sherpa is a 1976 model and the haynes manual will not cover your bike as it only covers models upto 1975. Get hold of an original or copy of a 158/159 model parts book Hope this helps Quote Link to comment Share on other sites More sharing options...
sunny Posted September 5, 2009 Author Report Share Posted September 5, 2009 I have the parts manual but the only trouble is that it has no explanations and need to rely on the manuals for tips on the process. I was looking at the parts manual and does the crank on the 159 only takes two bearings? The haynes manual shows three bearings I think. I was looking at it this morning and trial "fitting" the cases and it looks like it only has one bearing on each side of the crank for a total of two. Thanks for the explanations on the bearings Sunny Quote Link to comment Share on other sites More sharing options...
feetupfun Posted September 5, 2009 Report Share Posted September 5, 2009 The crankshaft bearing issue can be tricky if you look at repair manuals because some 5 speed motors have two bearings on one side and one on the other while others have only one bearing on each side. A point to note is that some people use a roller bearing one side to better allow for differential expansion between crank shaft and casings. This also makes assembly even easier. The ball bearing in the other side holds the crank in the middle. Another point is that the 5 speed Bultaco motor has a tendency for the main bearings to spin in the casings. It's usually no big deal, but it is a good idea to have a good look at the bearing seats in the cases to see of yours has had this happen. If the old bearing outers have been rotating, it is a good idea to have the bearing seats sleeved back to the correct size, using either steel or aluminium sleeves, to reduce the risk of it happening again. Providing enough bearing (balls to grooves) clearance is important because unless there is enough clearance within the bearing, differential expansion (crank to casings) will eventually work the bearing seat fit loose either in the cases or on the crank (as well as putting a lot of side loading on the bearings). Quote Link to comment Share on other sites More sharing options...
peterb Posted September 6, 2009 Report Share Posted September 6, 2009 Hi sunny, All that stuff what everyone else said and this bit more: Usually 1 bearing race either side on the 159, I always use C3 - higher clearence bearings in the crank case, don't cost much more than a std bearing. Definately no sealed bearings here. You need to heat up the crank case bearing housings either with a hot air gun, or even boiling water to fit in the bearing so as not to use brute force. I usually place the bearing in a freezer to contract it a little. Try to use hi temp viton oil seals for the crank case, I can't remember now but I think the older Gas Gas motor uses a similar sized viton seal for the crank case and may be readily available in your area P/N M01217001, 25x40x8 (the bikes up to 2002) - check it out with your manuals. Just out of interest, I run a roller bearing on the clutch side of my Bult with a ball race on the other side, I reckon the roller takes more axial load. Bye, PeterB. Quote Link to comment Share on other sites More sharing options...
sunny Posted September 6, 2009 Author Report Share Posted September 6, 2009 I was re-reading some of the posts that I have made sorry about some of the typos. I have made progress!! I cleaned everything and have blown it out with compressed air. I really am just trying to figure out what I have and what I do not have. I decided that I will reuse the "original" C3 bearings they seem to be in good condition --- they might have been replaced recently. My goal is to get it together and running and if in the future repairs need to be done then so be it. I love the experience of taking nothing and making it in to something. I am now ready to join the cases I have fit the crank and bearings. I just need to go over all of the gearbox stuff one more time to make it is all there. I am worried a little bit about the process it seems kind of like a one shot deal. If you do not get it all the way home you need to start all over. Pictures to follow Sunny Quote Link to comment Share on other sites More sharing options...
swooshdave Posted September 7, 2009 Report Share Posted September 7, 2009 I was re-reading some of the posts that I have made sorry about some of the typos. I have made progress!! I cleaned everything and have blown it out with compressed air. I really am just trying to figure out what I have and what I do not have. I decided that I will reuse the "original" C3 bearings they seem to be in good condition --- they might have been replaced recently. My goal is to get it together and running and if in the future repairs need to be done then so be it. I love the experience of taking nothing and making it in to something. I am now ready to join the cases I have fit the crank and bearings. I just need to go over all of the gearbox stuff one more time to make it is all there. I am worried a little bit about the process it seems kind of like a one shot deal. If you do not get it all the way home you need to start all over. Pictures to follow Sunny As someone who "started over" several times the first time I put a Bultaco engine together... luckily it's not hard to split the cases and just as easy to put them together. After a "few" times I had it down. Quote Link to comment Share on other sites More sharing options...
toofasttim Posted September 7, 2009 Report Share Posted September 7, 2009 As someone who "started over" several times the first time I put a Bultaco engine together... luckily it's not hard to split the cases and just as easy to put them together. After a "few" times I had it down. And you impressed your friends with your expanded vocabulary Quote Link to comment Share on other sites More sharing options...
feetupfun Posted September 7, 2009 Report Share Posted September 7, 2009 As someone who "started over" several times the first time I put a Bultaco engine together... luckily it's not hard to split the cases and just as easy to put them together. After a "few" times I had it down. Dave you aren't the only one I confess to assembling my M138 Alpina motor (my first Bultaco engine rebuild) three times in 2003 before I got it right Attempt 1 - crankshaft wrong way round (I managed to do this by holding a conversation while I worked) Attempt 2 - one shift fork installed backwards (it looked OK and fitted together nicely, but would only allow 1st and 2nd gear to be used) Attempt 3 - hooray, it all worked and has ever since! Quote Link to comment Share on other sites More sharing options...
swooshdave Posted September 7, 2009 Report Share Posted September 7, 2009 (edited) Dave you aren't the only oneI confess to assembling my M138 Alpina motor (my first Bultaco engine rebuild) three times in 2003 before I got it right Attempt 1 - crankshaft wrong way round (I managed to do this by holding a conversation while I worked) Attempt 2 - one shift fork installed backwards (it looked OK and fitted together nicely, but would only allow 1st and 2nd gear to be used) Attempt 3 - hooray, it all worked and has ever since! That's about how many times it took me. I don't remember why I had to pull it apart. Although I can't top the backward crank... My vocabulary did not increase... but it did get practice. I think it was probably because I didn't use a manual the first time, just an article from an old magazine which was more general, but eventual I got it. Overhaul Edited September 7, 2009 by swooshdave Quote Link to comment Share on other sites More sharing options...
john collins Posted September 7, 2009 Report Share Posted September 7, 2009 Sunny It really can be false economy to re use these bearings - if you have a good crank - and fit new new bearings - providing you put gearbox back together - you know you have a good bottom end - and any future problems can always be done with the motor still in bike. This is why I said if you really are strapped for cash - you could get away with ordinary 6205 ( without seals) or if your new 6205 has seals ( 2RS) just flip them out I know everyone tells you - correctly - to use C3 - but if you cannot locate them - use the 6205 - still better than putting old bearings back. C3 bearings should not cost you more than around Quote Link to comment Share on other sites More sharing options...
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