Tman has something like this, but the dipstick remains in place. He clarifies in one of his vids it's only really needed as added assurance for bigger builds. If I was seriously concerned about breathability of my oil tank and was pushing limits with a bigger build, I would definetely contact him directly and use his setup instead.

 

Not good. Shouldn't be that way at all. Never had any pressure build up in any of my Harley's like you described. Not even my 17 FLTRU had pressure build up and it had some issues. Recommend getting the dealer to take a look at it under warranty.

 

Doesn't appear this will work on the M8 Softails. If it did, I would buy one.

 

Fueling came out with a vented dipstick, so you can still check the oil level, but you gotta pay for it. $279.00 ouch.

 

A stock motor shouldn't have any pressure build up. I never noticed any after riding, then checking the oil.

 

Please forgive the typos above folks. Responding on my phone is sometimes detrimental. Lol. Hopefully, you got what I meant above. This pressure build up inside my oil tank so great, the dipstick coul not be removed by hand until the bike started cooling, it literally hissed like a snake when I opened it. Maybe not a problem on stock 107s and maybe even stock 114s, but the stock 117s and larger Bore setups, this might help significantly to protect from sumping.

I’m imagining what the possible impact is to the oil feed feed and scavenging process under this extreme high pressure condition. I think that’s why there’s been so many success stories with the oil pump backplate seal. Although I fear that’s more a bandaid than a fix as others have noted.

 

I've checked the oil in my 2017 FLHXS multiple times with the engine hot and never experienced any pressure build up of any kind. What does your dealer say?

 

Do you have a big bore kit in your bike? After pulling the CPS and draining 2+ quarts of oil out, my dealer said everything looked good. They said that they would replace my oil pump and add the back plate seal just in case. If nothing was wrong, the bike would have never sumped so I went my own way with new 124 Cylinders/Pistons and a Feuling race pump and cam plate. Just finished break-in miles. No pressure building up at all now.

 

There are several of these out there, if one looks around. The ones without a dipstick make it so you have to carry you stock one with you to check the oil. Some drill the casing to add a fitting and other vent right through the dipstick. They all have there bad and good sides, so pick your poison. It is all going to depend on how well they separate the oil from the air, prior to venting. If it just in the dipstick you may be smelling the fumes and get a small amount of oil accumulation around the dipstick area, the ones with the hoses may allow air and moisture to re-enter the oil case.

 

I say vent it to the primary. Probably using something like TMan's setup. That way if there is any oil leaking it will go right to the primary, the extra pressure in the primary might keep the transmission from transferring. If I was going to do it, that is how it would be done.