Author Topic: Oil in air box?  (Read 2285 times)

ratinthejat800xl

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Oil in air box?
« on: October 07, 2016, 06:02:15 am »
I just got an ft from a buddy. It died on him two years ago and has sat ever since. I just pulled the air filter out and there was 2-4 ounces of oil in the bottle of the air box. This oil was clear and looked new. However when I drained the oil it was black as night. Any ideas? Thanks. Perhaps too much oil was put in the engine when it was changed last and seeped up through the breather vent. I dunno I don't have any experience with this bike and my service manual hasn't come it the mail yet.

J6G1Z

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Re: Oil in air box?
« Reply #1 on: October 07, 2016, 08:10:08 am »
Could be due to a high oil level. What is the crank case oil level at this time?

Could be a sign of excessive piston ring blow-by.

Hard to say without seeing it & having the engine run.

J.

ratinthejat800xl

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Re: Oil in air box?
« Reply #2 on: October 07, 2016, 09:48:06 am »
I didn't check the oil level before I drained it.  :-\

J6G1Z

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Re: Oil in air box?
« Reply #3 on: October 07, 2016, 11:38:58 am »
How many miles on the bike?

J.

ratinthejat800xl

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Re: Oil in air box?
« Reply #4 on: October 07, 2016, 11:50:03 am »
10,000. And I just checked compression. I have 0  :( that's assuming my compression tester is working correctly.

ratinthejat800xl

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Re: Oil in air box?
« Reply #5 on: October 07, 2016, 03:09:17 pm »
I think maybe one of the exhaust valves is stuck open.

twerth

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Re: Oil in air box?
« Reply #6 on: October 14, 2016, 12:21:34 pm »
Was it a cleanable filter like a K&N or Uni? Maybe the element was over-oiled and it ran down to the bottom of the air box over time. That would explain why it was clean while the crankcase oil was black.
1984 Honda VT500FT
2006 Ducati ST3s
2000 Yamaha WR400

WTF304

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Re: Oil in air box?
« Reply #7 on: October 19, 2016, 07:02:35 pm »
Zero compression, oil in the air box ... I'd bet more on the intake valves. Jumped time, piston meets intake valves, jabs whole in the piston. While you've drained the oil, I'd check the timing and make sure they are set correctly ... might aswell check the balance shaft chain tension to. If the timing is off, I'd pull the carb and look down the throat of the carb and intake port of the head. I've seen where one of the screws on the butterfly valve in the carb came out and ruined a perfectly good engine. Basic checks will get you pointed in the right direction though ... fuel, spark, compression, timing. Compression loss can be a few things but it will 8/10 times be internal ... bad head gasket or wrong timing  is the other 2/10 I feel. Let us know what you find

smcohio

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Re: Oil in air box?
« Reply #8 on: May 21, 2018, 03:17:20 am »
Could also happen if the bike has ever been dropped. I have a similar story when I first tore down my bike. My wife was standing across from me while I was pulling out the air box and as I ripped the hoses out there was a small amount of oil in the breather collection box which flung clear up the front of her. Not a way to impress the wife lol.