armzngunz Posted June 20, 2018 Posted June 20, 2018 (edited) Hey, I have this old Yamaha DT125 from 1982. Last summer the crankshaft seals broke and sucked the gear oil into piston chamber which burnt up, gasoline and such would gather inside the cover of the flywheel... (unless the oil somehow got anywhere else) and my clutch broke without me realising before it was too late. I replaced the clutch, piston, pistonrings, cylinder seals and crankshaft seals (Left and right), I noticed that the crankshaft itself when I wiggled it had maybe half a millimeter of play up/down (-1 degrees celsius) on the right side, but I thought this was acceptable and put it all together. Now it's spring and I've finished putting it together, but there is this odd clanking/rattling sound and it behaves poorly, it also drips either oil or gas from the flywheel cover.https://youtu.be/lLcSixOXvPo <- Video showing me starting the bike and idling/throttling Do I have to split the case and replace the crankshaft bearings? Or could it be transmission bearings? Edited June 20, 2018 by armzngunz finally got video working
Moderator Airhead Posted June 20, 2018 Moderator Posted June 20, 2018 The link doesn't work for me! I think I'd be taking off the generator cover and seeing if theres any up/down movement in the rotor? movement here could cause the rotor to bind up on the various coils and heat them up with possible bad consequences?
armzngunz Posted June 20, 2018 Author Posted June 20, 2018 Link is working now, uploaded it youtube Might just be me being paranoid aswell but better safe than sorry
Moderator Airhead Posted June 20, 2018 Moderator Posted June 20, 2018 yeah sounds like a right old bag of spanners doesn't it! The quickest thing is to do what I said it's an easy check but then there's also the con rod big and small end bearings to consider
armzngunz Posted June 20, 2018 Author Posted June 20, 2018 5 minutes ago, Airhead said: yeah sounds like a right old bag of spanners doesn't it! The quickest thing is to do what I said it's an easy check but then there's also the con rod big and small end bearings to consider Ok, so when checking the generator if it moves, I assume there should be no play at all? I'll be checking it soon.
Moderator Airhead Posted June 20, 2018 Moderator Posted June 20, 2018 no up/down front/back movement, and i'm making an assumption the flywheel is done up tight
armzngunz Posted June 20, 2018 Author Posted June 20, 2018 (edited) 25 minutes ago, Airhead said: no up/down front/back movement, and i'm making an assumption the flywheel is done up tight I tried to wiggle it and there was no movement I could measure using my ruler, when using a pipe wrench to try and wiggle it I could hear a slight sound that might indicate some movement,aswell as feeling something that might be movement too. Turned the flywheel around a few times, still the same thing, occasional feeling that there might be movement, but too small to see/measure. It is definately leaking from the seal though. I used an impact wrench to tighten the flywheel nut, so I think it is tight enough. Edit: I'd like to add, I tried changing the spark plug, just to be safe, no difference. Edited June 20, 2018 by armzngunz
slice Posted June 21, 2018 Posted June 21, 2018 It's a long time since I owned a 2 stroke but that sounds like an end bearing to me ! Either crank case or big end, too deep a sound to be a small end I reckon, fraid it's gotta come apart again. I know you don't want to do it but it's either that or a long walk home from where it detonates.
Simon46 Posted June 21, 2018 Posted June 21, 2018 Grampian motors Liverpool will supply the rod fitted to the crank while you wait and bearings and seals required
armzngunz Posted June 21, 2018 Author Posted June 21, 2018 Ok, thanks, I'll see what I can do with it. I've never really split a case before, so if I can't get anyone to do it for me I guess I'll just have to watch alot of tutorials
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