Question about 1981 Yamaha XJ 650

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When warm will not stay running+leaks oil to the air cleaner

My dads 81 650 special will not stay running when its warmed up. Its like its losing spark maybe? Also leaks oil through the carb into the air cleaner on left carb and a little oil out the clutch cable hole.

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This is an XS 650, no? Sounds like you might have some piston ring blow-by (especially if its burning some oil), or possibly bad valve seal's'. The valves could be tight, so make sure the valve clearance is correct first, then compression test, and finally a 'leak-down' test.

If it is blowing by, it probably is fouling plugs and you will need more energy in the spark to fire, but this is a secondary issue, which will be eliminated with the fixing of the other issues. Good luck!

Posted on Jun 25, 2009


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If your engine has been sitting for a long period of time, your engine is probably "oil sumped". Since the oil tank is located higher on the frame than the engine, if the bike sits for a long period of time, oil will seep past the oil check ball and accumilate in the bottom end of the engine. I've seen the oil tank empty into the bottom end.

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Look on the back of the air breather assembly. There should be a pipe coming from the front of the engine on the timing gear cover on the right side of the engine going to the back of the air cleaner. Temporarily disconnect this pipe. Start the engine and allow it to run for a few minutes. Once the oil stops coming out of the pipe, reconnect it and disassemble the air cleaner. Clean the air cleaner. If the paper air filter is saturated, replace it. Reassemble the air cleaner assembly.

Now, Check the oil. Do not add oil to the engine as long as the oil is visible on the dipstick. Start the engine ride until the engine warms up. Now, with the engine warm, check the oil. The upper line is "Full Hot" while the lower line is "Full Cold". Set the oil level halfway between the lines. Do not overfill. If the bike is going to be sittting for a while, either drain the oil tank or start the engine about once a week and let it run for a few minutes. Do not allow it to overheat.

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