'78 Yamaha XS650

[Mavagrand]

I have a 78 XS650 that I have been rebuilding for a few years. Engine runs and frame is in good shape, everything else I have been slowly replacing, including the wiring harness, master cylinders, coils, etc. I am a little anal about replacing things that may not need replacing, after all some of these components are over 30 years old. My son and I have been debating about the need to replace the gaskets and seals in the engine. I say they need to be done, he says no need since they do not leak. I plan on riding this thing a lot once it's up and running so want to replace everything to avoid aother tear down in the future. What say you guys?

 

[ultra...good]

Sounds like you already know what needs to be done, or why you should or should not do. If you are in a hurry to ride and not worried about longengevity, don't worry about the gaskets. If you can wait a while to ride and don't want to have to take it apart again, then replace the gaskets. JMO
I waited 16 years to rebuild the '74, and now that I am, I am replacing everything that is questionable, all gaskets, brakes, bearings, seals, etc.etc. I don't want to have to take it apart again though. Again, JMO. Good luck!

 

[Lancer]

My wife has a 1981 XV750 Virago. I rebuilt and rejetted the carbs, recovered seat, painted, added windshield and saddle bags. Also went through 2 30 year old starters, finally got a new 4 brush starter off Ebay. It does seep a little oil from underneath somwhere. Anyway the bike runs like a champ, she road that thing to and from Memphis, TN (2000 miles by time we were done) last year and rides as often as she can locally. The old Vtwin motor on this bike is just about bullet proof. If that motor on the 650 is anything like this one I would go with it the way it is. But if you are trying to cherry it and really feel the need, do it.

 

[fin_676]

At that sort of age i would suspect that the gaskets and oil seals may not have long left in them and it may be that one good outing will have some failing
so if the bike is in bits anyway i would be setting out on an engine rebuild however you may find a lot more needing done once you start stripping

Brian

 

[Redfish-Joe]

Seals are cheap and pretty easy to get to. Rubber had the tendency to get hard after a while when combined with dino oil. I would suggest changing them.