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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: k on August 23, 2020, 09:06:26 PM

Title: What Is Causing This Oil Leak
Post by: k on August 23, 2020, 09:06:26 PM: When I am running for sustained periods above 70, or so, I get an oil leak from the right side of the bike. When I back off, the leak subsides, a bit. The crankcase gasket has been replaced, and the problem is unchanged.
Title: Re: What Is Causing This Oil Leak
Post by: blackie1 on August 24, 2020, 04:48:37 AM: can we assume , whilst on the center stand, your engine oil level at rest sits at/near the dot in the center of your sight glass?
Title: Re: What Is Causing This Oil Leak
Post by: stokester on August 24, 2020, 09:19:51 AM: Quote from: blackie1 on August 24, 2020, 04:48:37 AM
can we assume , whilst on the center stand, your engine oil level at rest sits at/near the dot in the center of your sight glass?
and your oil cap has an o-ring?
Title: Re: What Is Causing This Oil Leak
Post by: Chaos on August 24, 2020, 09:37:30 AM: I think there's a screw hole in that bottom corner of the airbox, if you're getting enough blowby to collect oil in the filter housing it could be leaking out there. And check the o ring on the oil filler cap.
Title: Re: What Is Causing This Oil Leak
Post by: Laitch on August 24, 2020, 10:59:53 AM: If it's pooling at the red arrow, it must be flowing from some place to get there. Clean off all traces of oil then apply bath powder on the area around the upper crankcase cover seam and the pooling area. Blow off the excess, go for a ride at 70mph, stop, then see if any powder residue reveals tracks from the source. It's likely the crankcase seam is leaking, especially if the cover has been off or it has received a shock from the bike's falling over on that side.
Title: Re: What Is Causing This Oil Leak
Post by: k on August 24, 2020, 10:14:21 PM: I put the oil cap from the K1100 on the K100, put some corn starch on it, and took it out for a half hour.

I can't find a leak.
Title: Re: What Is Causing This Oil Leak
Post by: Laitch on August 25, 2020, 01:26:07 AM: Congratulations on finding the source of the problem. 112350
Title: Re: What Is Causing This Oil Leak
Post by: k on August 25, 2020, 06:11:00 PM: Quote from: Laitch on August 25, 2020, 01:26:07 AM
Congratulations on finding the source of the problem. 112350

I wouldn't go that far. I just didn't spot a leak in a half-hour ride.
Title: Re: What Is Causing This Oil Leak
Post by: Laitch on August 25, 2020, 08:23:47 PM: True, it seems like you didn't go that far. I rescind congratulations and substitute, Have a nice day, whenever that might start.
Title: Re: What Is Causing This Oil Leak
Post by: k on August 26, 2020, 10:31:58 PM: Still leaking. I can't make it leak with high RPM and low speed. It will leak at high RPM and high speed.
Title: Re: What Is Causing This Oil Leak
Post by: Laitch on August 27, 2020, 12:15:03 AM: Did you try tracing the leak with the cornstarch method again?
Title: Re: What Is Causing This Oil Leak
Post by: koapono on August 27, 2020, 06:59:48 AM: just a thought:
there are a couple of crankcase vents in the area under the air-box. If those hoses/rubber caps are original they might be source of leak. The engine block has many nooks and crannies under the air-box, they may be filling with oil and leaking out in area you highlighted.
Title: Re: What Is Causing This Oil Leak
Post by: Snowman on October 15, 2020, 05:33:39 PM: I agree with Koapono, Likely a vent hose either split or out of place. Sustained high engine RPM makes it worse.