Reinhoud Posted January 6, 2019 Share Posted January 6, 2019 Gents, I'm busy building up a GS1000 crankshaft, stronger con-rods. According to the specs the runout should be 0.1mm max. The sideway runout I've got to 0.04mm accurate, but the up and down (factory) runout is 0.28mm. This far out of spec, does anyone had this seen before? I did mark all the parts, but even if I hadn't, it shouldn't be out this far.. Thanks Quote Link to comment
Dezza Posted January 6, 2019 Share Posted January 6, 2019 Maybe there is variation in bearing manufacturers. I say this because when I recently rebuilt a small two stroke and replaced the main bearings I had to source a thinner end float shim or otherwise the crankshaft locked when I tightened the cases. Presumably this was due to different manufacturing tolerances between different bearing manufacturers, even though I used good quality bearings (SKF). Quote Link to comment
Arttu Posted January 6, 2019 Share Posted January 6, 2019 What you are actually measuring and how? I haven't done much measuring by myself but a local crank builder said that many stock cranks are over that 0.1mm spec. Any way, 0.28mm sounds quite a lot. Quote Link to comment
Fazz711 Posted January 6, 2019 Share Posted January 6, 2019 Have you some how ended up with extra clearance bearing. Not sure what std is but bearings come with a choice of clearance eg c2 fairly std use c3 for extra clearance when something runs a bit hotter then c4 for a lot hotter eg oven fans. Quote Link to comment
markfoggy Posted January 6, 2019 Share Posted January 6, 2019 I would be interested in what you are measuring here. Or rather trying to. Is a roller bearing crank, so when it is spinning it should center on the bearings. If that tolerance is lateral float, maybe the manual is misleading you and you have already got it crazy tight. 1 Quote Link to comment
Reinhoud Posted January 6, 2019 Author Share Posted January 6, 2019 I don't think it's a bearing thing.. Quote Link to comment
Gixer1460 Posted January 6, 2019 Share Posted January 6, 2019 I think thats gonna need some persuasion with the heavy engineering adjustment mallet! Is it welded yet or just pressed - could have pulled with the welding (if it was!) Quote Link to comment
no class Posted January 6, 2019 Share Posted January 6, 2019 deffinately some issues with concentricity ! hopefully it is not welded yet as it can probably be indexed / trued . Quote Link to comment
Reinhoud Posted January 7, 2019 Author Share Posted January 7, 2019 Look, this is adjustable, and is within spec. Quote Link to comment
Reinhoud Posted January 7, 2019 Author Share Posted January 7, 2019 This is fixed, and this is out of spec, that's the issue. The manual says 0.1mm max run-out, sometimes this has 0.15mm run-out, but 0.28mm I haven't seen before.. Anyone have seen it before being this far out? Quote Link to comment
Arttu Posted January 7, 2019 Share Posted January 7, 2019 (edited) Yep, that's clearly over the spec and you should fix it before using it So is this something that you have rebuilt or did it came from a running engine like that? Edited January 7, 2019 by Arttu Quote Link to comment
Reinhoud Posted January 7, 2019 Author Share Posted January 7, 2019 I think that's the crank what came out of my bike, but not sure, I had another engine laying around, could be from that engine too.. Quote Link to comment
Gammaboy Posted January 10, 2019 Share Posted January 10, 2019 Are you locking it down to the stand? Doesn't look like it where the centre bearing supports are. Clamp it down, measure, and then take it out and fix with a tree stump and a BFH (Brass faced Hammer, well, copper actually). wear eye protection! Quote Link to comment
Reinhoud Posted February 15, 2019 Author Share Posted February 15, 2019 So... Got myself another crankshaft.... After pressing it together I had the same problem, only the runout wasn't as bad as the previous crank... That means the mistake must be me Did some measuring, turned out pressing it together didn't go as straight as I hoped for. A little bit on an angle causes the runout, now all is within 0.03mm. Problem solved. Quote Link to comment
RickC Posted June 9, 2020 Share Posted June 9, 2020 There's a lot more to putting a crank together that I ever realised. 1 Quote Link to comment
Reinhoud Posted June 9, 2020 Author Share Posted June 9, 2020 I did do the indexing completely different. I have a set of old crankcases and cylinders and pistons, I build that all up, and used 2 dial indicators to see when the pistons stopped and started to move. The thing was that the pistons could stop equally, but started differently, it doesn't sound logic, but I had to find a way in between that. It wasn't very hard, mostly time consuming, it was a very interesting job to do. 2 Quote Link to comment
Reinhoud Posted June 11, 2020 Author Share Posted June 11, 2020 The bike with the crankshaft from this topic is running again, and there are no excesive vibrations, actually less as before.. I'm pretty happy with that. 2 Quote Link to comment
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