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Life throws things at you!
- jwonder
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Life throws things at you!
They are not hard, and I was told (and have receipts from the previous owner) that the motor was rebuilt in the last 4 years. They look fairly new.
Now, I am sure I know the answer to this already but figured I would ask. (fingers crossed) Is there anything I can do with this without pulling the cylinder to replace them? There were no oil leaks but I only was running it on the stand.
Thanks for any guidance!
James
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Vice President, Vintage BMW Motorcycle Owners
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- schrader7032
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I hate when that happens! At
Ultimately there's a small, small chance that "stuff" can find its way into the cut. So, you'll need to replace them eventually. I suppose you could put the cylinder at TDC, loosen the four base bolts and pull out the top end enough without going past the piston rings. Replace the seal and reverse the process...do both of them. The cylinder base should really be cleaned and a thin layer of non-hardening sealant applied. You would need to be sure the pushrods found their proper home...probably best to loosen the rocker arms before start this.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
Squeezed
That kind of splitting can happen if the pushrod tube shoulders are too close to the engine case therefore squeezing the seals too much. But based on the looks of the one that’s not split they look about right, but it’s hard to tell for sure with a picture. It’s been my experience that most of the aftermarket rubber bits that are being made for these old bikes are really poor quality rubber. Nowhere even close to the quality of the original stuff. But sadly we don’t have much choice in who the supplier is. It’s a problem not only with rubber parts but other things too. The wiring harnesses currently coming from Germany are just horrendous quality now for instance.
If you do end up taking it apart, you might sort of carefully assess just how much the seal is being squeezed, and if you feel it’s too much you can tap the pushrod tubes into the cylinder a little deeper. Those seals will do their job just fine only being compressed a little bit.
- wa1nca
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Push rod tube
They are not hard, and I was told (and have receipts from the previous owner) that the motor was rebuilt in the last 4 years. They look fairly new.
Now, I am sure I know the answer to this already but figured I would ask. (fingers crossed) Is there anything I can do with this without pulling the cylinder to replace them? There were no oil leaks but I only was running it on the stand.
Thanks for any guidance!
James
Looks like that push rod tube was never inserted all the way into the head and damaged the seal because it put to much pressure on the seal
The seal can be replaced by removing the 4 lower cylinder nuts
Then the cylinder can be move up enough to insert the new seal but will damage the new seal because the push rod tube is not inserted all the way into the head
So the cylinder needs to be removed and that push rod tube needs to be tapped in all the way so one edge of the tube is flush with the top of the head
Should also renew the cylinder base and head gasket at the same time
Good news is parts should be less than $20.00 and if you do the labor then just your time
Did you ever get your charging problem working
Tommy
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA
- Micha
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I had the same issue with my
I inserted the replicas that I purchased at Mark Huggett, Swiss.
They split in the same manner.
I was upset, pulling everything apart, again, and used the old one with a smear of heat resistant engine RTV.
Don’t know what to use or buy this winter, as I intend to overhaul the motor.
R51/3 1952
Engine Nr. 529466
that sucks, James but I'm
but I'm afraid I would agree with Tommi ... the push rod tubes are not far enough in the cylinder head so that the shoulder of the tube applies too much pressure on the rubber seal. If you do the "KISS" method fix of the problem, you will end up with the same split seal.
IMHO - depending on your current weather - I would continue driving the bike and wait until it gets worse or you have another reason to pull the cylinder. The seal is more or less in the corner where the rubber gets squeezed into the opening of the engine case ... as long as this part is still intact ... you might be lucky.
In case you plan to cross the country I probably would fix it right now.
I am surprised about Micha's experience with Mark's rubber seals since I strongly believe his rubber parts are the best you can get in the market. Rabenbauer in Germany is also a very good source (my number one source for parts) but I think his rubber parts also come from Mark. So, I guess you won't find any better quality.
good luck
Klaus
- schrader7032
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Not sure if this is what
Oak Okleshen provided a diagram that showed where the position of the tubes needed to be relative to the cylinder base. It was specifically for the /5-on bikes. So, not sure if it applies here. But this is what he recommended for positioning of the seals. This is my interpretation of what Oak provided.
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'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- wa1nca
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Push rod tube length
The total length of the r51/3 tube is 94 mm
The total length of the r67/3 tube is 104 mm
The total length of the r68 tube is 100 mm
Tommy
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA
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pull the head
- jwonder
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Update on seal, new question
I pulled the head and cylinder off today asI am all about making sure things are right and I am quite a perfectionist. Everything looked good as I was getting in there but as I was cleaning things up I noticed that the CYLINDER IS SLEEVED! Ugh.....
I have read that a sleeved cylinder does not transfer heat well, but this sleeve looks like it was put in very good and I have ridden the motorcycle and the motor ran great. The cylinder wall looks good as well. I would love to know your feelings on this! I would like any ideas on the sleeving of these cylinders for the R51/3. It looks like a good job IMHO.
Thanks for any help!!!
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Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York