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rmichel13
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VBMWMO #9224
Joined: 01/26/2017
Posts: 11

I am working on a 1974 BMW r60/5. It has been sitting for 25 or more years. When I got it the motor turned over with ease. It had no compression. I pu lled off the heads and replaced the piston rings an reseated the valves. I after re-assembling it I still 30 lbs. in the left cylinder and stillnone in the right cylinder. the valves are as loose as I can make them. Any suggestions?

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Bob Michel

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6327
What does "reseated" the

What does "reseated" the valves mean? Are you certain that the valves are completing resting on the seats? One way to do that is to place the heads upside down on the bench on top of some paper towels, then power something like AFT into the combustion chambers. If no fluid gets to the paper towels then the valves are resting perfectly on the seats.

New rings will need to be broken in...doubt they're sealing well at this point.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

312Icarus
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Joined: 07/15/2016
Posts: 275
Assuming the valves are

Assuming the valves are adjusted properly (and you did no timing gear work) either the valves are leaking, or perhaps the ring gaps are improperly aligned. Ring gaps all in the same place will leak through the gaps.

With the valve cover(s) off spin the engine and watch the valves, and as suggested check the valves for leakage. Maybe a bit of carbon or grinding compound on the seats. Possible a loose valve seat?

Icarus

PS did you hone the cylinder when you put the new rings in? Try pouring some oil in the plug hole and see if you get better PSI compression on that side. If so, suspect rings not sealing. (Wrong ring size, too much end gap or, or, or?)

bstratton
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Posts: 90
Try doing a leak down test

With that little compression you should hear a hurricane either through your valves or through your dip stick hole. I have the same motor but a little older. It had a smokey left cylinder when I started the restoration so I had a valve job done by my local machine shop, honed the cylinders and replaced the rings and put it all back together with new gaskets. Runs great and no smoke. It took a few days for the rings to seat. You should see 145 lbs or so (using the starter to tick it over). These are high compression motors. Technically the motor should be at running temp when doing a compression check but if it ain't running that would be tricky. If you are not familiar with leak down test google it. There are some good videos out there specific to classic BMWs

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Bstratton
1971 R60/5
1965 R50/2 (project)
MA

MikeL46
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Joined: 01/01/2016
Posts: 38
You have three places to lose

You have three places to lose compression:

- Headgaskets. Are the heads/cylinders flat, true and smooth? Gaskets dry or coated with a good headgasket sealant?

- Valves. Are the valves closed when at TDC? Is the valve timing accurate?

- Piston rings. Is the bore round? Are the pistons the correct bore size; Std, +.025mm etc.?

My guess would be the valves are not closing, or not closing at the right time.

Mike

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67 R50/2 w/R100 engine/trans and Ural Sidecar
69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar

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