Fixing Special II Crankcase Leaks

gene xs

XS650 Enthusiast
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I bought a Special II a year back with the intention of flipping it. It's stock and even still has the cowhorn bars.

Once the carbs were cleaned it fired right up but the cam chain was very noisy. I got the engine removed last weekend and got the forward cam guide replaced with one of Gary's prototypes (thanks, Gary!).

After it ran, I noticed some oil drips from the large acorn nuts on the bottom of the crankcase. What I found as I disassembled the engine yesterday was that the PIO (not the PO in this case, but a previous irresponsible owner) attacked leaks by using drying gasket sealer on the side covers and cranking the snot out of the nuts on the bottom of the crankcase.

My plan now is, once I have the top end back together, to loosen all the fasteners on the bottom of the crankcase and insert sealing washers on all the tall acorn nuts (I will use steel Dowty washers that have rubber inserts rather than copper washers). The fasteners will be brought to the proper torque in stages and criss-cross fashion.

I have 3 running (and one on deck) Yamaha RD250s and 350s. When you have a leak you have to pull the case halves apart and reseal them. But this is mainly to avoid air leaks into the crankcase from the timing side and oil leaks from the clutch side. It's not to avoid oil drips.

The XS650 case joint is well above the oil level in the sump, so I don't think that the joint would be a source of leaks. I did not see any leaks from the joint.

My question is this: Am I OK with just attacking the fasteners on the bottom of the case? Cracking the cases does not scare me (I've done the 3 RD's), but if I would like to avoid it if I can.
Dowty Washers.jpg
 
Yes, you should be fine changing the washers one at a time. Here's where you should find acorn nuts and sealing washers .....

rC7PBrW.jpg


Hopefully this will solve your leak issues but tracing oil leaks to their source can sometimes be difficult. The oil just eventually ends up dripping from the tall acorn nuts because they're the low points.
 
I'm not seeing any signs of leakage from any of the seals - so that's good news. I am planning on pulling the sump plate and reinstalling it with a new gasket. I will do the same with the starter gear case cover. Thanks for all the help!
 
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