mystery motor opinions?

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xTomx

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Hey everyone new to the site and would like some feedback!

Started a new bobber project, its a 74 xs650, got titled frame, bottom end, harness, and some other goodies for really cheap. The rods have some surface rust but not too bad and inside of the cases it looks fine. Rotates very smoothly, and no serious crank endplay.

Now with that said should i go through the time of opening it up? I know how much extra work it is to get these apart and would rather not but id like some imput!

Thanks
Tom
 
If the top end is already off, and it were me, I would go the rest of the way and open it up, might be a little inconvenient, but if you put it all together and something is wrong, that would be way more inconvenient, but I'm kinda paranoid, so someone else may have another suggestion, good luck
 
If the top end is apart it really is not that much more difficult to split the cases. I would suggest while you are in there to go ahead and replace all the seals so you don't have any unexpected oil leaks that you have to address later. I just got done rebuilding my motor and was expecting to have to fight with the case halves but it really was not that difficult at all. While you are at it check the copper coating on the inside of the small end of the connecting rods and and your sump filter, cam chain guide etc(all the known weak points on these old motors) and clean clean clean.
 
Just posted in your other thread - if that is your motor photographed in the other thread, you definitely need to pull the cases apart.
If you even entertained the thought of running it then I suggest you get a manual + get someone to help you who can give an opinion of the condition of your bottom end.
Not trying to shit in your weet-bix here but looks like you need some hands on assistance - there are plenty of people here who will give their opinions & advice also.

Good luck.
 
yeah, man, drag that thing over here to shelton, and i will help you.
I think it was bdholsin that took his cam chain adjuster out, and found a sae nut just sittin right there in side on the ledge. And his motor was complete when he got it.
 
Awesome glad theres lots of helpful people on this forum! kinda didnt know what to expect in the yamaha forums, so thank you really appreciate it!

Just started to split the cases. And holy crap its dirty. Looks like this things been sitting in a garage for 20 years. Bearings are good kinda worried about the copper on the rods, ill have to inspect it better here soon.

Angus67 i might have to take you up on that the further i get into this thing, im not too far from you over in Puyallup
 
sweet. I got a friend over there with a 1980, and a 71.
he needs some prodding to get going on his 80 chop. i'll see if we could meet there. sometime.
 
Holy shit these cases are STUCK. Already attempted the oven idea, after i got passed the screaming wife to the oven only to find out it didnt do a thing. might give it another shot here after it cools back down. Rubber mallet didnt do a thing and im stuck :(

And yes... i removed all 18 nuts and bolts including the "hidden" one everyone seems to miss

HELP! PLEASE!
 
Everyone says it's easy, but the halves are basically glued together, so it can't be real easy... I'm going to follow your progress.
 
yup. no gasket there, just yamabond. keep tryin. but be carefull where you pry(if you pry). what ever you do, dont hit the upper case where the right side cover has that stick out spot above the drive sprocket. it will break off easy, then there is no support for thr clutch action, resulting in a spongy clutch.
If I remember, there is a good pry spot behind the clutch basket. take out the clutckbasket, dont forget how all those washer came out, becuase they have to go back in the same way. I think its next to that hidden nut you said you took off.
do you have the cases upside down? for some reason, mine came apart easier upside down, and must be re-assembled upside down.
 
This is the current state of my engine. Fingers crossed.

bbqtime.jpg
 
wait a fuckin minute man, get that thiong off there. where do you live? i can come over tomorow. and help you out. do nt do that. you missed some thing. please dont do that.
 

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