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Thread: 1978 R100/7 Topend Overhaul

  1. #121
    Smoooooth at 430 gch71's Avatar
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    Super nice project!!

    Awesome project, super happy to see an airhead back on the road, nice detailed explanations, very nice indeed.
    Now what color is your bike, what does BMW call that blue? It looks like my R60 but I do not have the label under my seat anymore.....
    Thank you for the awesome posts!! Enjoy that ride.
    And great article in ON mag!!
    Glenn
    ...driving to work on my airhead
    '74 R60/6, '75 R60/6(boxes)

  2. #122
    Administrator 20774's Avatar
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    Glenn -

    Thanks...I'm anxious to get back on the bike and begin racking up the miles. I want to get 500 on it before heading off to the rally. It's a tough job, but someone has to do it!!

    AFAIK, the blue is called Blue Metallic. I'm not near the bike but think the color code is 533. You can check for codes here:

    http://bmwmotorcycletech.info/pcodes.htm
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #123
    Smoooooth at 430 gch71's Avatar
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    Thank you sir...
    Glenn
    ...driving to work on my airhead
    '74 R60/6, '75 R60/6(boxes)

  4. #124
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    This was a fun read!

    Congratulations!

  5. #125
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    50 Miles In!

    Oak recommended this point to at least recheck torque. I also went ahead and changed oil to get out any of the particulates from the break-in...hopefully that's all in the filter which I will open up for a looksee.

    I checked clearances before torquing just to see what was happening. Both exhaust clearances were fine before and after retorque. The left side intake was down around 0.10mm so I reset that after retorquing. The right side intake was a tight 0.15mm but got smaller after retorquing so I set it back to 0.15mm. The right side exhaust rocker was kind of loose...explains the louder sounds on that side. So, I adjusted the pillow blocks to allow some very slight up and down motion.

    After changing oil, I grounded the plugs and spun the engine to circulate oil. Light went out, so I buttoned things up.

    Now for some more riding! Engine feels very nice, good power/torque.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  6. #126
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    You put pistons on rods first and then slid cylinders over pistons. If you'd put pistons with one snap ring installed inside the cylinder first, slid them together over rod and then installed wrist pin, do you think you'd have been able to install the 2nd snap ring? I'm thinking of getting a set of these pistons and cylinders myself.

  7. #127
    Administrator 20774's Avatar
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    Installing any of these snap rings was a big biyotch! Well, the first one I did on the piston alone...I could push it into the hole, turn it 90 degrees, and square it up with a close fitting socket, finally push it home to the slot. But doing the second one with the wrist pin in place was tough. And by the time I got around to the second one, the tips of my thumbs were very sore.

    I'm not sure assembling everything with the piston/rings already inside the cylinder would help much. For me, I think that would be more restrictive. I needed as much working room with both hands wrapped around the exposed piston on the end of the rod, while I struggled to get the snap ring to start in the hole. Having to worry about moving the cylinder too much and still get my hands around the piston would just be asking for frustration.

    When I discussed this with Ted Porter, I mentioned my lack of "enthusiasm" for internal snap rings. He mentioned he kind of liked them. I suspect there's a trade secret in getting in and out...but I wasn't given the handshake. I just hope that I don't have to deal with them again in another 100K miles!
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  8. #128
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    You say that the Siebenrock pistons are the same for both sides you just needed to make sure the pockets were pointed the right way. Is that the same with stock pistons? I've been told by a local BMW mechanic that the wrist pins are offset in the vertical plane. This is so that offset of the sparkplug firing wouldn't cause the pistons to rock and wear out the pistons and cylinders more. When I've had mine apart, I couldn't see it. I just made sure I put them back the same way I removed them.

  9. #129
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    I had also heard about the offset on wrist pin...I believe I did measure the different on the old pistons. The tops of the old pistons were so mucked up, I couldn't see anything, but the idea is to have the arrow pointed to the front of the bike. As I mentioned in an earlier post, I was concerned that the pistons could be installed in two ways, but still have the arrow pointing to the front. In both cases, the valve pockets would have been oriented correctly...very important. But in switching sides, the offset, if significant would have also switched sides of the piston in a vertical direction. I emailed Ted Porter about this subject and he said just be sure the arrow points to the front...that was all I had to worry about.

    I also thought the offset had to do with how the power pulses affect the direction of push on the piston and subsequently the rod when it was at TDC. This would help prevent any serious rocking of the piston. I'm not sure that's correct or not. But if the offset can be changed vertically by swapping the pistons side-to-side, seems like this might have been an issue.

    In my case, I opted to have the writing on the piston crown readable and with the arrow pointing to the front of the bike.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  10. #130
    Macrunch MCrenshaw's Avatar
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    Great write up Kurt. Your bike looks exactly like my first BMW, except it was an R60 and had the black bags. Airheads rule! Just curious to know if Mr. Porter recommends adding a ZDDP additive to the oil for valve life?

  11. #131
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    Quote Originally Posted by mcrenshaw View Post
    Just curious to know if Mr. Porter recommends adding a ZDDP additive to the oil for valve life?
    He never mentioned it. Many ZDDP discussions on the list...not sure if you caught my thread on oil testing and the article in the March 2013 ON. For my tastes, I just try to buy the best oil I can with the right amount of ZDDP. Matt Parkhouse had indicated that there can be too much of a good thing when it comes to ZDDP. Buy a quality oil and change it often...that's all you need to do.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  12. #132
    Macrunch MCrenshaw's Avatar
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    Saw the article but haven't read it yet. I'll go back an do that. Probably right now because Dancing with the Stars is on my my wife must watch it. Usually the R90 gets a good quality oil, most commonly a Castrol GTX and I definitely try to change oil & filter often. My Ford F150 has 321k miles and I still change the oil every 3000 miles.

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