To split the case... Or not to split the case. That is the question.

Hey guys. Thanks for looking. I picked my kid up a 1985 SP250 that seemed like a decent starting point to chop up and make into something cool. Started tearing into it before I noticed oil leaking out of a couple of the case seams. I've got to do a clutch anyway, so if it had just been one of the side covers, no big deal, but it's leaking out of the center seam at the back as well. That smells like a complete tear down to me. I'm generally not afraid of taking things apart but haven't been in this deep before.


Complete gasket set, oil seals for shifter, kick, clutch shaft, primary... Plus the head and jugs need to come off. How the hell can I go that far and not replace the piston, cam chain and chain guides? Where does it end? Stop the insanity! We just wanted a cheap scrambler!


I mean, it's not like I can throw some stop leak in there. Guess it boils down to whether the bike is worth the weekend and another couple hundred bucks in parts. What do you figure the flat rate book says hours wise to re-seal this motor up?



To me it comes down to how much oil is it really leaking. old bikes when they sit have a few seals that dry out but swell up and seal after a bit of running. Also if the leak an't too bad and you can keep up with the oil consumption why do a tare down. But this coming from a guy that has had a few older brit bikes. The joke goes "you know why Brits don't make tvs ?? They an't figured how to make them leak oil yet." It is a personal thing I guess.

Sometimes owners of older bikes decide to treat their bike to full synthetic oil  and the bike will develop leaks....especially if the bike has been sitting around a bit .


When the engine is cool (cooler the better) loosen and retorque the case bolts one by one, don't overtorque.   Change oil to old fashioned dino oil and see it it slows the leak any.


Depending on how bad it is  and if the bike is running good otherwise,  put a skid plate on it stuffed with high-temp insulating foam.....tell your friends it's to cut down on noise reverberations or something, and just change it out now and then.



I have a 77 XL350 that I am pretty sure is leaking from the counter sprocket shaft oil seal.  I leave a pan under it.  :rolleyes: hardly ever run the bike and I am sure it is a dried out seal and I am not splitting the cases to replace it. 

I have replaced these by drilling a small hole in the outside of the seal being careful not to go deep into the engine when the bit goes thru.  Then I screw in a wood screw into the hole and grab that with vice grips and yank it out.  Sometimes takes 2 screws 180 degrees apart.   No need to split the cases. Good luck with it.

Edited by ronbuell

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