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skyler.robbins
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VBMWMO #9513
Joined: 09/22/2018
Posts: 97

Hey Gang,
I'm doing an exhaust thread repair on the right cylinder.
I took a couple pictures of the head/piston area.
I noticed that the exhaust valve was a lighter brown color and had a lot of buildup on it.
The piston seemed pretty wet and oily.
I'll clean both up, but do you see anything out of the ordinary or I should be aware of?

C.K
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israel
Joined: 01/08/2014
Posts: 147
Its ok.

Its ok in general. How many miles on it?

312Icarus
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Joined: 07/15/2016
Posts: 418
How does the bore

How does the bore look?

Icarus

skyler.robbins
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VBMWMO #9513
Joined: 09/22/2018
Posts: 97
54,000 on the speedo...

54,000 on the speedo... however, when I bought the bike last Summer, it didn't have a speedo cable, so there's that.
Haven't checked the bore or anything yet... literally just pulled both heads last night and that's as far as I've got.
Both exhaust valves have a pretty good carbon build up on them.

Question,
How do I know which valve guides to order?
Do I have to wait until everything's apart and measure?
I'm seeing a couple different sizes out there on the nets.

Thanks!

wa1nca
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VBMWMO #8374
Ashfield Ma.
Joined: 09/27/2012
Posts: 545
Valve Guides

Should be original not over sized if never bored to a larger size at some point
It would be wise to measure the old ones to be sure

Tommy

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Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US 68 Sears Allstate 250 (Puch)

malmac
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VBMWMO #8751
Toowoomba, Australia
Joined: 06/29/2014
Posts: 300
R69s guides larger than R60 guides

Not sure if R60/R50's had different sized guides but I am sure that the R69s had larger diameter guides.

Mal

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mal - R69s
Toowoomba- Australia

skyler.robbins
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VBMWMO #9513
Joined: 09/22/2018
Posts: 97
Thanks guys... Will get on it

Thanks guys...
Will get on it here in a couple days and measure up stuff/check bore.

pokie
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VBMWMO #70
Joined: 02/08/2015
Posts: 134
What now

With that kind of mileage, you should really consider doing the slingers. If you only rebuild the top end, the old slingers will be overfilled and a seizure may be imminent. This is also a good time of year to do the slingers as you may need to send out the bottom end, shops will be looking for work.

skyler.robbins
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VBMWMO #9513
Joined: 09/22/2018
Posts: 97
Piston pics..

pokie wrote:

With that kind of mileage, you should really consider doing the slingers. If you only rebuild the top end, the old slingers will be overfilled and a seizure may be imminent. This is also a good time of year to do the slingers as you may need to send out the bottom end, shops will be looking for work.

No slinger cleaning this time around.
Probably next Winter.
I'm trying to contact the previous owner to see if perhaps he did it or knows when/if it has been done.

Got a chance to clean up the pistons and look at stuff.
Everything is looking great.
Here's the numbers on my pistons.
71 95
2/68

I'm guessing the first numbers are the size?
Second is manufacture date?

My bike is a 1969

  • kimg0490.jpg
  • kimg0491.jpg
malmac
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VBMWMO #8751
Toowoomba, Australia
Joined: 06/29/2014
Posts: 300
Its about the clearance

Yes they look nice and clean and that is promising - no obvious scoring for instance.

However it is about the clerance - if the wear is well beyound the factory tolerances - then it will rapidly burn oil, foul up and not be happy.

Just measure it up so you know where you stand.

Mal

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mal - R69s
Toowoomba- Australia

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6844
My R69S pistons had 1/68

My R69S pistons had 1/68 stamped on them...inside the piston was a number 12/67 which I suspect was the date of the mold. BMW said my bike was built in the spring of 1968 but wasn't sold until December 1969, thus resulting it being classified as a 1969 model. I think motorcycles were not selling well at the time and dealers weren't ordering bikes as often, so mine likely sat at the factory for several months. So your stamp of 2/68 could be the same situation...it might not have left the factory until late in 1968.

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

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