weasel Posted December 16, 2012 Share Posted December 16, 2012 Hello, I have a OS120 MK111 that needs the front bearing changed i have purchaced both front & rear bearings and was wondering if this is a akward job to carry out..? looking for some assistance on were to start.... Regards Weasel...... Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted December 16, 2012 Share Posted December 16, 2012 I've done SC, OS and Magnum 4 strokes without any great hassle, just be wary when you put the cam back in as it's easy to get it on the wrong tooth. There'll be a mark on the cam to line up at tdc. Usually this mark lines up with the pushrod tubes but I'm sure someone on here can confirm how OS marks are set. Quote Link to comment Share on other sites More sharing options...
Mark R Posted December 16, 2012 Share Posted December 16, 2012 Hi W, i am sure someone will correct me on this...but i am sure its similar to when i changed the bearings on my Irvine 53.... 1) stripped engine of piston,head,back plate...so all that is left is the crankcase with the bearings. 2) Put oven on, i have gas so its gas mark 5/6 for me 3) Make a brew while oven heats up 4) Place crank in oven 5) forget to put oven mitts on and pick up crank then drop quickly....put on oven mitts after about 5-10 mins of heating engine 6) The rear bearing should! fall out straight away, it did on mine, tho the front required a lil help. If u use a stout bit of thick dowl to 'persuade' it out, from back plate hole thru crank case to front bearing and give it a bit of a tap it should fall out. 7) Crank has probably cooled a bit by now so new bearings might not fit in straight away, you can put back in oven again just to warm up and let metal expand, then i put front bearing in first, mine required a lil persuasion with block of wood over the top of bearing to stop it from being damaged, then i 'tapped' with hammer. Rear one went in really easily and both seated nice once crank had cooled. 8) check bearings are turning nice and freely on their ball bearings. 9) I out a lil 3 in 1 oil on bearings, some use other lubricants, personal taste really 10) I lightly all the piston, piston pin etc before reassembling in reverse order. 11) Manually check everything works nice and smoothly. 12) If your happy....start her up If all the above is not how you do it apologise, but its the way i do it. Mark Quote Link to comment Share on other sites More sharing options...
Bucksboy Posted December 16, 2012 Share Posted December 16, 2012 Go onto U Tube and search for OS bearing replacement,there are some great videos explaining everything. Very good and clear too. I followed them changed the bearings really easily. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted December 19, 2012 Share Posted December 19, 2012 Is it a 2 stroke Weasel? If so Marks instructions are good so follow them.......SWMBO might not like you using the oven though so maybe a hot air gun or a carefully applied blow lamp will do the job......ideally you would get the cases smoking hot & the bearings will fall out A 4 stroke is much the same but you need to do a good bit more dismantling to arrive at the "crankcase 'n' bearings only" stage...... YouTube is your friend here...... These show an OS52 but the principle's the same..... Edited By Steve Hargreaves - Moderator on 19/12/2012 14:43:53 Quote Link to comment Share on other sites More sharing options...
weasel Posted December 19, 2012 Author Share Posted December 19, 2012 Thanks Lads for the information, will give it a go after the weekend will keep you posted on the outcome. Steve the lass would not notice if the engine was in the oven as she is kinda mule on the culinary skills thats left to chef Weaz... Hot bearing stew on offer next week with added gravy.. Weaz OS bearing chef Ne66 Quote Link to comment Share on other sites More sharing options...
Concorde Speedbird Posted December 19, 2012 Share Posted December 19, 2012 120 mk one hundred and eleven! Blimey, OS designers are always on the ball! Just joking, I'll be interested how you do (some pics will be nice) since at some point I want to change the bearings on my 70 surpass. CS Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted December 19, 2012 Share Posted December 19, 2012 If you get stuck------- come on down Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted December 19, 2012 Share Posted December 19, 2012 weaz....remember the car window at greenacre's youngin...that was a display of your mechanical skill's....leave the engine alen.......... ken anderson ne..1 ---a was there dept. Quote Link to comment Share on other sites More sharing options...
weasel Posted December 19, 2012 Author Share Posted December 19, 2012 Hello Sir jim. Have you got recipie for the os cooking stew ? Yes that will be sound Jim i have quite a lot of free time on the work situation near your area, will give you a call if i get into any trouble... Sir Jim Carss Weasel's chief engineer..... Quote Link to comment Share on other sites More sharing options...
weasel Posted December 19, 2012 Author Share Posted December 19, 2012 Ken the window auto glass extrodiner helper found the right materials for the job and it is still working like a swiss watch... Am still ok with the Hammer if things need adjusted. Weaz Kendos apprentice window technician.... Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted December 19, 2012 Share Posted December 19, 2012 Quote Link to comment Share on other sites More sharing options...
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