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It's a rubber seal and rear cover that seals the rear of the pump to the right main bearing boss. Stops the crank case from breathing through the bearing.

Theory would seem to be that by limiting the ability to breath, they increased the peak positive pressure pulse in the crank case. That puts a little more push on the oil trying to enter the scavenge port at the bottom of the case.

This would also indicate that the issue has been the pump sucking the cam chest dry and air locking, leaving oil in the crank case. Exact same issue that plagued the early twin cam. They went out side the company to sort that issue out and ended up with a redesigned pump.

I think the best fix out there is the three stage pump. A separate scavenge pump for each section of the case. But that's way more money than the MoCo will spend to fix the existing scooters.
 

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Well watta ya know.....because of all the issues people were having i didnt wait for it. Rode my 2018 King Special to the 1000 mile mark, and put in a Feuling hi-perf pump and their camplate....of course while in there a hot cam, new lifters, w lifter collars and adjustable push rods....absolutely no issues.
 

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Seems new Harley motors take a few years to uncover and fix issues that should/could have been engineered right to begin with... Haven't paid much attention to M8s, but this and a few others seem fairly significant.
 

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No, just a revised part.

If you take it in for sumping, under warranty, its a free upgrade. But they have to prove its sumping first. Some dealers will drain the case, and make the call. Others go by the book and make you ride it until it sumps again.
Thanks, THerm.
 

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Another issue I just would like to know why do some seem to have it and others do not. My early 2017 M8 has no issue with the so called sumpping and neither do any of the others I know of personally. And yes I do right mine and you can bet the sidecar puts more stress on it.
 

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Its actually a high RPM issue when the engine has so much vacuum/pressure that the problem occurs. people who do long distance high RPM, and in almost every customer complaint about it, when I ask them about it, 90% of the time the day before it happened they were with a group traveling on freeway.

Setting the oil level on M8s has become one of my biggest pain in the ass service procedural matter.

When setting the oil level on the M8s you must let the bike run on side stand a full min or 2 after the bike has reached operational temp. Its the only accurate way I have been able to get true levels, and this info came down the pipes from the top, I can not remember reading this anyplace in a document at that time although it might be documented now. Ill check a owners manual and service procedure now, but If the techs in the shop set them like we use to after a test ride by letting it set on the side stand,m for about 5-10 min before adjusting it, odds are the level will be way over filled...

Im not sure why it needs to idle on the stand 1-2 min, but I have my theories.
 

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Its actually a high RPM issue when the engine has so much vacuum/pressure that the problem occurs. people who do long distance high RPM, and in almost every customer complaint about it, when I ask them about it, 90% of the time the day before it happened they were with a group traveling on freeway.

Setting the oil level on M8s has become one of my biggest pain in the ass service procedural matter.

When setting the oil level on the M8s you must let the bike run on side stand a full min or 2 after the bike has reached operational temp. Its the only accurate way I have been able to get true levels, and this info came down the pipes from the top, I can not remember reading this anyplace in a document at that time although it might be documented now. Ill check a owners manual and service procedure now, but If the techs in the shop set them like we use to after a test ride by letting it set on the side stand,m for about 5-10 min before adjusting it, odds are the level will be way over filled...

Im not sure why it needs to idle on the stand 1-2 min, but I have my theories.


Edit its in the owners manual now..
You must let M/C idle 1-2 min after operating temp is reached on the side stand, before setting the final level...

If you do not do this step, the chances of over filing the M/C will be very high.

 
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