Martin G from Race24 Posted July 25, 2011 Report Share Posted July 25, 2011 Trying to help a mate get his twin shock Yamaha DT400 (big old two stroke single) running right. What symptoms would we expect to see if the crankshaft seals needed replacing? It's been stood for years, and while I think they probably need doing, he wants to carry on tinkering with the carb. Thanks in advance... Link to comment Share on other sites More sharing options...
wazrs257 Posted July 25, 2011 Report Share Posted July 25, 2011 To be honest, if its been stood for that long & you can get the parts, replace them anyway. Its only a couple of hours job. You could spend weeks p!ssing about with the carb and get nowhere! Link to comment Share on other sites More sharing options...
Gregorious77 Posted July 25, 2011 Report Share Posted July 25, 2011 Symptoms would be running lean normally and oil leaking into magneto/flywheel area. Not worth messing about leaving it and hoping just get the seals replaced! If they are shot the worst case is lean seize/hole in piston wrecking the whole engine! Link to comment Share on other sites More sharing options...
Gregorious77 Posted July 25, 2011 Report Share Posted July 25, 2011 Oh symptoms of running lean are high idle and the revs taking a long time to drop back to idle after blipping the throttle, also a hollow boooohhhhh sound (Bogging)if you snap the throttle open quickly. Link to comment Share on other sites More sharing options...
Martin G from Race24 Posted July 26, 2011 Author Report Share Posted July 26, 2011 Thanks people. It actually seems to be running very rich, but we don't know if someone exles hasn't already had a poke round in there... MG Link to comment Share on other sites More sharing options...
cagimaha Posted July 26, 2011 Report Share Posted July 26, 2011 If it's the clutch/primary drive side oil seal that's gone then it'll draw gearbox oil in and burn it resulting in a sooty/wet plug. Link to comment Share on other sites More sharing options...
Martin G from Race24 Posted July 27, 2011 Author Report Share Posted July 27, 2011 Seals and puller ordered. Thanks for all the answers. MG Link to comment Share on other sites More sharing options...
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