R75/6 oil pressure valve leak (disk valve)

[schrader7032]

I don't recall where you were located. You don't have to be next door to a good mechanic that can do heads for these bikes. I had the heads converted to unleaded seats/valves on my /7 and it was done by Ted Porter in NorCal. Easy enough to box them up per his instructions and send them via mail. There are other people who work on heads that might be closer.

[srankin]

Hey don't feel bad about being amateurish, we are all there at first. You are doing the right things by getting advice on what to do and you are taking it as well with a good attitude. I myself will work extra hard to help someone with your attitude.

Don't get me wrong, I am not chastising you for not doing a machine shop honing. You may very well get by with what you have done hence my suggestion to ride it, give it time for the rings to seat/break in then if later, the problem still exists you can remedy it.

If you do decide to have head work done, it is wise to view Ted Porter's video regarding why it is important to find a machine shop who knows how to properly rebuild BMW airhead heads. I had three sets of heads done before I saw this and now, I shudder to think they may not have been done right. Oh, they are running fine, for now, who knows for how long, if I am lucky, for a long time. LOL

As Kurt mentioned, we don't know where about you are located. I am near Rochester NY. I have my own lift and tools and I have a dedicated airhead shop forty miles from me which is my second home. So if you are near by, I would be glad to help out in anyway even if it is just an extra hand to hold a flashlight.

Regarding extending the oil pan for extra oil. There have been reams of articles in various forums over the years citing the pros and cons of this.

I will give you my two cents on the subject; save your money, stick with the stock pan. The same goes to for adding an oil cooler. In fact, I had a factory oil cooler and deep pan on my RS, I removed the cooler because in my climate, it is not needed and makes doing oil filter changes a real pain in the ass. There is some controversy the placement of the cooler in front of the engine radiates extra heat which in turn can damage the diode board behind the front cover. Again there are reams of pro and con about that. I plain and simple got rid of ti because it was not needed and made more grief in the filter change.

As for the deeper oil pan, I have a stock pan on my RT and it has run 200+K miles with never a problem. I did find when I switched my center stand on the RS from stock to a Reynolds ride off stand, there is only one stand that will fit the deep pan bikes. I got lucky and found one.

Best thing to do with any airhead is keep the oil topped off, or at least keep oil in it, LOL. And change oil frequently. Oil is cheap, engine parts are not.

You are on the right path, enjoy the restore or repairs, know there are people who can help, and enjoy the ride. St.

[Andey]

Unfortunately I’m on the other side of the world. Appreciate the offer of build support.

I’ve watched Ted’s videos on cylinder heads a bunch of times..! Great info to look out for and lessons learnt that airheads need special treatment. I would hate to have someone over bore the seats or just hammer the wrong size valve guides in place, seems like a nightmare...

Having Ted Porter work on my heads would be a dream. Someone who has that much experience on airheads would be ideal. I had some of Ted’s special spline lube shipped to me and added it to my final drive spines, the previous owner has copper grease exploding out... I’ve never found so much grease anywhere before!

I was asking around about final drive lube and Ted recommended his special mix. The guy is a gent...

I’d love to ship my heads to him, but shipping would be a killer. Having the heads reconditioned would be great, at least its one of the things I can tick it off the list of items that eventually need servicing...

Your insights on the oil pan and oil cooler makes sense... I’ll keep riding on the stock pan and slowly observe what happens. I think frequent oil changes might be the way to go for me...

[srankin]

On the other side of the world? If you are down near Melbourne AU, I can give you the name of a BMW airhead guru who would be very happy to fix you up with people to help you out. St.

[Andey]

Not quite, but near enough timezone. I do travel to Melbourne, so might be a useful contact.

I'd love to connect with anyone with advice on the bikes.

[srankin]

This fellow Frank Cachia is one of the noted gurus on the R90S bikes, he used to run the international R90S website for years.
He lives and breathes motorcycles and is involved with a few large clubs in AU.

One of my best Mates, we email daily, and have been doing so for 20 or more years.

Here is his email address: r90s@ozemail.com.au

He doesn't have a website.

You guys in AU have a much different view/outlook/way with vintage and classic bikes and cars. I am always amazed at the bikes and cars Frank tells me about which are being ridden and driven there. It is hard to put into words the difference but sometimes, I really wish I could get over there especially during our winter, your summer LOL. Cheers, St.

[snowbum]

Snipped from my oil sketch article. You likely do not have this settling hole...if you do, be sure it is clean, use a stiff piece of wire.

Engine castings from 1977 or 1978 had a 1.5 mm drain-back return bore hole, item 22 in the sketches. In this area much of the breather vapors condense and the resultant oil is returned to the crankcase. Item 22 is called the "Return Bore in Settling Chamber" while the somewhat harder to understand item 21 is the actual settling chamber. Item 20 is the breather valve. Shown in the sketches are the earlier spring loaded round breather valve disc (adjustable to two positions for smaller versus larger engines). The disc type tends to get chipped edges and also sometimes makes noises, often called or described as a Turkey Gobbler, or; rarely, honking (usually that noise is froma noisy main seal of the old style). A new breather disc can be made from something like printed circuit board material, if one wanted to. The later reed type can be installed in earlier disc type engines. There is really nothing wrong with using the disc type, although they sometimes make noise.

I actually prefer the earlier disc types. If your early disc is making objectionable noises, and the disc is in good condition, and mounted with the correct clip position, you can usually eliminate the noise by drilling, carefully, ONE ONLY 3/64" hole, at approximately the 50% of radius position. The early model breather looks like a round disc with a small spring and a holding clip on the shaft. There are two grooves in that shaft, the top groove is used for the R50/5, R60/5, R60/6 and R75/6, and the bottom groove is for the R75/5, R90/6 and R90S. The round type of breather valve can be removed and the later style installed. There is nothing wrong with the operation & design of an early disc type breather valve if the disc is in good condition. It is arguable if the later reed type works better, but it is quieter & does not seem to ever wear out. You can make a new round disc from approximately 1/16" thick fiberglass electronics printed circuit board material. The diameter needs to be 27 mm (about 1.06"); and the center hole #2 drill bit (about 0.22"). See the note earlier in this paragraph about drilling a hole, if need be, for objectionable noises.

Source for newly made old-style Airhead breather discs:
$5.00 for each disc; which includes USPS. Dave Thompson dtvic@comcast.net

Snowbum

[Andey]

This fellow Frank Cachia is one of the noted gurus on the R90S bikes, he used to run the international R90S website for years.
He lives and breathes motorcycles and is involved with a few large clubs in AU.

One of my best Mates, we email daily, and have been doing so for 20 or more years.

Here is his email address: r90s@ozemail.com.au

He doesn't have a website.

You guys in AU have a much different view/outlook/way with vintage and classic bikes and cars. I am always amazed at the bikes and cars Frank tells me about which are being ridden and driven there. It is hard to put into words the difference but sometimes, I really wish I could get over there especially during our winter, your summer LOL. Cheers, St.

Thank you St! I will definitely reach out, especially if I’m in the area... does Frank still work on the Airheads?

[Andey]

Snipped from my oil sketch article. You likely do not have this settling hole...if you do, be sure it is clean, use a stiff piece of wire.

Engine castings from 1977 or 1978 had a 1.5 mm drain-back return bore hole, item 22 in the sketches. In this area much of the breather vapors condense and the resultant oil is returned to the crankcase. Item 22 is called the "Return Bore in Settling Chamber" while the somewhat harder to understand item 21 is the actual settling chamber. Item 20 is the breather valve. Shown in the sketches are the earlier spring loaded round breather valve disc (adjustable to two positions for smaller versus larger engines). The disc type tends to get chipped edges and also sometimes makes noises, often called or described as a Turkey Gobbler, or; rarely, honking (usually that noise is froma noisy main seal of the old style). A new breather disc can be made from something like printed circuit board material, if one wanted to. The later reed type can be installed in earlier disc type engines. There is really nothing wrong with using the disc type, although they sometimes make noise.

I actually prefer the earlier disc types. If your early disc is making objectionable noises, and the disc is in good condition, and mounted with the correct clip position, you can usually eliminate the noise by drilling, carefully, ONE ONLY 3/64" hole, at approximately the 50% of radius position. The early model breather looks like a round disc with a small spring and a holding clip on the shaft. There are two grooves in that shaft, the top groove is used for the R50/5, R60/5, R60/6 and R75/6, and the bottom groove is for the R75/5, R90/6 and R90S. The round type of breather valve can be removed and the later style installed. There is nothing wrong with the operation & design of an early disc type breather valve if the disc is in good condition. It is arguable if the later reed type works better, but it is quieter & does not seem to ever wear out. You can make a new round disc from approximately 1/16" thick fiberglass electronics printed circuit board material. The diameter needs to be 27 mm (about 1.06"); and the center hole #2 drill bit (about 0.22"). See the note earlier in this paragraph about drilling a hole, if need be, for objectionable noises.

Source for newly made old-style Airhead breather discs:
$5.00 for each disc; which includes USPS. Dave Thompson dtvic@comcast.net

Snowbum

Thanks Snowbum, and thanks for the encyclopaedia of information..! I would have been completely lost without your references

I don’t think I would have been able to work on the bike so quickly without the info.

Yup it’s an earlier version of the crankcase, so no drain hole that I can see... I’m wondering if the spring is too worn to hold the disc down... would that be a thing that would happen?

[srankin]

Hello, Frank does not work on the bikes however, he is very connected with the airhead BMW community in the area.

I know one of his Mates, Dieter restores old bikes and I will bet Frank or Dieter would be able to connect you with help or sources of local parts. St.