I was flushing my engine after a ride on the weekend and noticed that the main seal on the crankshaft had popped off - thankfully the Yamaha designers put 2 seals there so it wasn't as bad as it could have been. The engine is a 650 that has been bored to 701 with a few other mods like reeds and pipe (I can add more detail if it makes a difference). Any ideas on what can cause the seal to come off like that? Is it likely to have caused any other damage? Can I just pop it back on and hope for the best - it looks like a right bastard to replace.
Sounds like what happened to mine - the seals that come with replacement cranks are shit. By the sounds you should only use genuine Yamaha crank seals and you should be sweet. If they are leaking you'll be getting air and even water in there, so not good. Hopefully it hasn't let any water in to rust your crank. Not the kinda thing you want to leave and hope for the best.
Yeah mine did that too and turned out it had been put in reversed with the inner seal on the outside. u gotta pull the engine out to replace it.
seal you wil have to replace you will run it two kean an could seize piston you will have two take engine ott remove crank cases
So it sounds like they are installed incorrectly ... I will check the marks on them tonight ... If they are can someone confirm that I will need to crack the cases to install them correctly. If this is the case it sounds like a new gasket set etc. I understand that I should only be using genuine Yamaha gaskets as the aftermarket one's are not as good, can someone also confirm this, and suggest a good place to source them. Cheers
You will have to split the crank case to put in the new seals. there is no gasket around the crank case just some glue shit that you get from yamaha.
I think what you need is a gasket for the cover that goes over the stator and sealant for the case, they use a liquid sealant - use Loctite 518 flange sealant. I've had the crank seals pop out because they were of inferior quality, the cost of genuine seals is a lot less than a new crank so for the sake of a few seals I'd try and get genuine ones. Can anyone else verify that this is correct? I'm just going from what I discovered from when the same happened on mine.
OK, so Waxhead was right - the one with the 4 bumps was on the inside, so they were installed incorrectly. So my next question is how do I get the coupling flange off? And is it OK to secure the crank at the other (flywheel) end while doing this? i.e. is there any possibility of twisting the crank if I do this?
