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Thread: 1978 R100/7 Topend Overhaul

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  1. #1
    Administrator 20774's Avatar
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    1978 R100/7 Topend Overhaul

    Well, I guess it's my time in the barrel!! I'm looking at going to Salem and have over 100K on the clock. Have been getting somewhat worried about the valves and have had some pinging off and on. So, out with Oak's manual and we're off!

    Things have gone fairly well. I have not had the exhaust nuts off in, say, 25 years! I know, I know...supposed to be a yearly thing. But before the Internet, I ruined one of the exhaust ports because I didn't know that aluminum-on-aluminum galled. I was the first to take the nuts off shortly after I got the bike, so I'm not sure what really happened.

    Rather than take a chance, I went straight for the hacksaw. That took me quite some time to cut through and pry the nuts apart. I'm glad I did. They were dry as a bone. Guess the anitseize I put on so many years ago sublimated!

    After that, mufflers and headers. Not too bad.
    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!

  2. #2
    Administrator 20774's Avatar
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    What not to do!

    My left pushrods had a wear mark about midway...guess where the head gasket was? This is wrong folks! The right side was fine.
    Attached Images Attached Images
    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. #3
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    Some serious build-up in each combustion chamber. That's the carbon that was probably glowing and setting off the fuel. I don't have lot of experience but the exhaust valve looks to be slightly deeper into the head than the intake. Here's the left side:
    Attached Images Attached Images
    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!

  4. #4
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    ...and the right:
    Attached Images Attached Images
    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!

  5. #5
    Administrator 20774's Avatar
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    I was happy to see that this Sep 1977 build /7 has no base o-ring and external circlips:
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    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. #6
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    I'm sending the heads off to Ted Porter. I probably won't do much in the next few months unless I get fired up to move forward. I need to clean up one side of the exhaust threads...a little bunged up but really not bad. I have one of those metric thread file tools - part K-D2228. I just need to figure out how to use it.

    http://www.mechanicstoolsandbits.com...28-p-4189.html

    I'll also be pulling the conrods and inspecting/replacing the bearing shells. At least that's what everyone says to do.

    As some point, I'll pull the jugs and see what kind of shape the cylinder is. Again, not a great deal of experience, but I see some cross-hatching on the walls...not sure how deep it is. If I'm out of spec, I'll probably be heading for new Nikasil jugs and rings.
    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!

  7. #7
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    PRT replacement with internal circlip

    Quote Originally Posted by 20774 View Post
    I was happy to see that this Sep 1977 build /7 has no base o-ring and external circlips:
    My May build r100rs had the internal clip which probably doubled my total job time. Started with the left, right side did go quicker once my "technique" was refined. Anyone attempting this job with the internal clips is advised to buy several extras- inevitably, you'll bend a couple if it's your first rodeo.

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