zookrick Posted June 1, 2017 Share Posted June 1, 2017 (edited) I have a '90 GSXR 750 crankshaft that is chewed up some, picture included. Is this too far gone or could it be polished without opening up the bearing clearances too much? The top journal I have worked on some with a shoelace, 400 grit and wd40. the bottom one is pretty much the way the rest look. Edited June 1, 2017 by zookrick Quote Link to comment
Gixer1460 Posted June 1, 2017 Share Posted June 1, 2017 Depends on what size bearings it has presently - I believe there are 3No bearing sizes to allow for factory machining tolerances - if the relevent journal is undersized already and there isn't another undersize bearing to go then its either leave well alone, metal spray and re-grind or scrap it. I wouldn't try DIY crankshaft re-facing! LOL! Quote Link to comment
zookrick Posted June 1, 2017 Author Share Posted June 1, 2017 The bearings are all toast, I will be buying new ones, probably would use one size smaller on each to make up for any material removed. Quote Link to comment
Fazz711 Posted June 1, 2017 Share Posted June 1, 2017 You would need some plastigauge to check the clearance. And a manual for the tolerance to work to. It won't be easy to polish to an accurate degree. Especially if you do it by hand. Quote Link to comment
dupersunc Posted June 1, 2017 Share Posted June 1, 2017 Step away from the tools and put the emery cloth down. No Suzukis need to get hurt here son. 2 Quote Link to comment
kja.busa Posted June 1, 2017 Share Posted June 1, 2017 I think I have a 750M crank in the shed, complete with shells if you get stuck. Quote Link to comment
Swiss Toni Posted June 1, 2017 Share Posted June 1, 2017 I have a 750 J/K crank here too, if needed! Quote Link to comment
zookrick Posted June 1, 2017 Author Share Posted June 1, 2017 Well a used replacement would be better if shipping is not too much. I am located in Canada. I ordered a crank off fleabay, but it is unusable for me and not worth the shipping cost to send it back, which is frustrating. 1 Quote Link to comment
Swiss Toni Posted June 2, 2017 Share Posted June 2, 2017 I'd get a crank local to you if possible. Postage from UK will make it expensive. Didn't realise you were in Canada! Try Eblag, or Craig's List? Quote Link to comment
no class Posted June 2, 2017 Share Posted June 2, 2017 12 hours ago, zookrick said: Well a used replacement would be better if shipping is not too much. I am located in Canada. I ordered a crank off fleabay, but it is unusable for me and not worth the shipping cost to send it back, which is frustrating. It would make a nice coffee table lamp ..... Quote Link to comment
canamant Posted June 2, 2017 Share Posted June 2, 2017 (edited) I've seen worse than that and put it back together. Suggest you check what shells you have fitted already and buy the next tighter shell and test fit it. Note that there are no "undersize" shells just different toleances. Also remember that a 90/91 crank cant be swapped with a 88/89 crank. Edited June 2, 2017 by canamant additional info Quote Link to comment
ktalgsto Posted June 13, 2017 Share Posted June 13, 2017 When I did my crank it looked almost like yours , and I took it to my local machine shop which I have been going to for years , and he said polishing will not take any material off it will just take the high spots off and polish it , I put all new bearings in that the bike came with color coded and numbers on the crank and block , and it came out perfect , but always plastic gage them , I did just to make sure. Quote Link to comment
strima Posted June 13, 2017 Share Posted June 13, 2017 A bit more costly would be get the crank away to someone who does crank chroming and grinding. Should come back good as new. Quote Link to comment
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