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Post new piston install, oil not circulating?

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So I had a problem with the trans and needed the bottom end opened up to fix a binding 3rd gear. My mechanic recommended a new piston while she was apart. So I picked her up and I noticed the oil level was low and not visible in the window. We filled it to proper level and when we ran her, oil gurgled out the breather tube and again the window went dry. I am guessing that for some reason the oil is not circulating, failing to complete the circuit.

Any ideas what could be the cause? Known blockage points? Scavenger pump issue? My mechanic is baffled. He is factory trained and has rebuilt hundreds of motors. Help!

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The first place that I would look is the oil screen on the flywheel side of the bike. I don't know if it would cause this symptom but it is known for getting plugged. Good Luck

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Did you initially check the oil window with the bike on the side stand? If so, you would have gotten a false low reading. Then, when you added oil, the engine would have been overfilled...resulting in oil coming out the breather when started. Then, if you had rechecked the oil without letting the bike sit for 5 or 7 minutes, you would have gotten another false low reading because the oil was still up in the engine......

That's all I can think of. The lubrication system cannot pump oil anyplace within the engine/gearbox that the oil cannot return...by gravity....to the sump.

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you need to run the engine for about 30 seconds to allow the oil to circulate, then shut it off and wait about 2 minutes. The oil level should be halfway up the window with the bike standing upright. If it sits for a few hours you need to restart the engine before you can check the oil level again. Hope that helps.

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I don't use that sight window for level check. I drain it, and put the required amount +50cc and leave it at that. Change it every few rides.

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When they inspected the oil pump they found that the pin that holds the impeller to the shaft was not there! It had dropped and once put in properly.....problem solved? Not sure how they jacked up the reassembly, but no more breather coughing oil!

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Took her out today and was stoked with power and suspension setup. I took my 2 smoke to Baja for a five day weekend last week and I wish I had the KLX for the trip. The KX head with stage2 hot cams make her a beast. Love that electric start!

That pin could have caused a disaster, thanks for all the input.

Edited by jimmyh

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