Sumping / oil transfer on the Milwaukee Eight ?

I'm considering buying a Road King, 107 M8 engine. It'll be my first Harley. Its come to THAT time when I'll have to get one after all these years .

I've read several stories about oil transfer or 'sumping' problems with the milwaukee eight engine. Has anybody had any experience of the problem or has an idea of how common it is? Or is it just over exaggerated internet scare stories?

Would it be possible to spot the problem on a test ride?

I've read of several solutions including drilling a hole in the crankcase or an improved oil pump.

Thanks in advance

Buy a BMW.

I’ve had two Milwaukee 8 engined bikes and done over 16k miles on them (a Fatboy and my current Road King Special) without any issues and they have been very reliable.

I’ve read about the sumping/oil transfer issue but I think it’s very rare and as your bike will probably come with some kind of manufacturers warranty I wouldn’t worry about it.

The Milwaukee 8 is a great engine with loads of smooth torque and power and also runs cooler than the previous versions of the big twin.

My brothers 107 RKS has gearbox to primary oil transfer (awaiting warranty fix).

My 2019 114 RKS already came with the primary case breather.....no issue whatsoever.

Crankcase sumping seems to be an issue more with the 117 and above and usually when ridden hard for many miles, not something I’d be worried about TBH, certainly not as worried as I would be if someone drilled a hole in my crankcase

If I was going to big bore the 114 I’d definitely factor in an S&S pump, but The 114 with a cam is all the Harley I’ll be needing.

Thanks guys (and JuanKing ) .It’ll probably be. 107 road king so won’t be getting any hard riding.
Local dealers don’t have a road king demo so they offered a street glide, which seems quite different to me but they reckon was closest ride, frame, suspension etc. Hoping to have time to try one this week. Cheers

Easiest way it to check the inside of the rear of the primary for the venting tube.

If it’s a 2019 or newer then I believe they We’re done at the factory.

Mezza said:

Thanks guys (and JuanKing �� ) .It’ll probably be. 107 road king so won’t be getting any hard riding.
Local dealers don’t have a road king demo so they offered a street glide, which seems quite different to me but they reckon was closest ride, frame, suspension etc. Hoping to have time to try one this week. Cheers

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The standard Road King or Road King Special are the best touring models in the current HD range IMO. Good secondhand ones are getting in short supply allegedly as dealers are currently offering to buy back some bikes.

Street glide will feel very different cos of the Batwing - same base model but the Batwing changes things quite a bit from the rider experience- if you want a Road king find a dealer that has a demo and travel a bit further...

The gearbox > primary oil transfer scenario is no big deal TBH - it's been there occasionally on all the twin cams & now more so on the M8s. Not something you will be able to analyse during a test ride, but you will be able to spot whether the primary case breather valve is evident.

I'll leave the Doc to explain ............. https://www.youtube.com/watch?v=QolhZGpFULQ
If you are into proper HD beards, then there is another hands on vid on 'The Ornery One' YouTube channel which shows the actual work being carried out.

Then you mention sumping, by which I assume you mean wet-sumping; not a problem I have come across with HD TBH. Possible I guess if the oil pump/valves are worn or sticky, but not something that would detract from buying an M8. Let's face it, most UK bikes won't have significant mileage & will have been well treated/serviced compared with the average Stateside. Someone like Eagle Rider will see their hire bikes hit 50k pretty quickly in a season, with very few problems. Again here is the Doc talking about the 2020 pump upgrade .......... https://www.youtube.com/watch?v=I4RJIZGr558