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Thread: 1978 R100/7 Topend Overhaul

  1. #31
    Administrator 20774's Avatar
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    I plan on a round of measurements to see where I stand and see what needs to be replaced. I ordered my first round of parts yesterday, things that I will need no matter what.

    As for FM1604, it used to be called the "Death Loop" because it was a two-lane road that ran out in the country and people were getting killed by cement trucks, etc. No longer...the city has engulfed 1604...it's now a 4-lane divided highway (mostly) around the city. To get to any cruising roads, you have to go farther out now...not much farther, though.
    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. #32
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    getting head job

    Quote Originally Posted by 20774 View Post
    I have an email into him right now to get a quote. I asked him about this in February 2011 when I was thinking about it, but put it off. It was $685.00/pair and he said he uses the Euro two piece exhaust valves and the steel alloy intake valves.
    My 100/7 has over 300k right now, about 65k and in a hurry I cross threaded the spark plugs resulting in the need for a helacoil insert. That required taking the heads off or leaving fileings in the jugs. Bought a valve lapping kit and proceded to make like a cavemen starting a fire. Seated both valves and 200k+ miles there are still going strong. Cost about $10.00.




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    sometimes I don't know if I should giggle at the strange things in my head...or should I be afraid?

  3. #33
    Administrator 20774's Avatar
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    I've made my first measurements of the cylinder bores. The jugs have the letter "B" stamped on them, so that is the size that I'll be looking at. I'm using a t-bar handled vernier to make the measurements. I've not done this very often...it's difficult to ensure that the t-bar is pointed exactly straight up and that the two tips are touching on exact opposite sides of the bore. I can stick my hand into the bore to turn the vernier to get to max dimensions, but the ends that touch the cylinder walls sort of "stick" and I have to keep checking to be sure they are at the maximum dimension. Is there an easier way to do this? This is what I'm using:
    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. #34
    Outlander Omega Man's Avatar
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    When I have done measurements like that Kurt, I have used an inside caliper-



    and then checked that measurement with a digital caliper. A sharpie can be used to make "quadrant" dividers and the process can begin. I kinda like that tool you have there in the picture Kurt for verifying the end result. A bore that has been run seems to have too many places that are a little different but I think that tool will work fine- just have to get the "feel" for it. Gary
    "Well they say.. time loves a hero but only time will tell.. If he's real, he's a legend from heaven If he ain't he was sent here from hell" Lowell George
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  5. #35
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    inside mic

    Can You push a ring in to the bore with a piston to use as a reference for holding the mic square?

  6. #36
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    Gary -

    I don't have one of those...it might be easier to find the exact opposite sides of the bore. My bore gage sort of "sticks" but I'm concentrating on moving it back and forth to ensure that I've found the maximum dimension. I also use my digital calipers to read the distance. The built-in caliper seems to be accurate once I figured out how to read the dial.

    franko - I don't really have a problem keeping the bore gage square...I can look at the handle to see if it is parallel (to the eye) to the centerline of the bore. The problem is moving the t-bar part of the gage to get the maximum diameter. It's a bit fiddly.
    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. #37
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    I made my measurements (in my limited amateur experience!). Here's what they are (in mm):

    Left: Fore-aft direction:

    Top - Mid - Bottom
    94.01 - 94.06 - 94.06

    Left: Up-down direction:
    94.03 - 94.04 - 94.05

    Right: Fore-aft direction:
    94.06 - 94.07 - 94.07

    Right: Up-down direction:
    94.06 - 94.06 - 94.05

    These cylinders are stamped "B" and Haynes gives the dimensions as 94.015 - 94.025. "C" cylinders would be 94.025 - 94.035. As it stands, it looks like I'm beyond spec for these. I think I'm going to find a machine shop and get them to repeat my measurements to give me the final results.
    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. #38
    James.A
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    When I did my R100/7, I was prompted to go into the motor when I discovered a 25% drop in compression on the right side cylinder. In the absence of a huge irregularity like that, I don't see where your measurements are alarming. I certainly can't read "ovalled" in those measurements. One might expect some wear on the bores on a motor that has been run.

  9. #39
    Monza Blue 1974 R90/6
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    Kurt, thanks for sharing process and asking questions. I am learning.

    Barron

  10. #40
    #4869 DennisDarrow's Avatar
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    Is there a problem with inserting a ring into the cylinder and measuring end gap? This is done with a new ring, old one that came off, and top bottom and mid of the piston travel. I know this is kinda old school; but it sure does show any gaps under the ring itfelf and how much wear has actually taken place.......God bless.........Dennis

  11. #41
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    Dennis -

    I think the suggestion for putting the ring into the cylinder was to provide a basis for squaring off the bore gage. I didn't really think that was necessary. I haven't pulled the rings off the pistons yet, but when I do, I'll put them back into the bore, align them with the piston, and measure the ring gaps just so I have the data point.
    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. #42
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    I'm going to remeasure using a telescoping gage set such as the following:

    http://tinyurl.com/azr7rfb

    A co-worker has a set that that I can use to get a precise dimension of the bore, and then use my digital calipers to determine the diameter. It supposed has rounded ends which automatically finds the max dimension...the other bore gage I used didn't have that and let me unsure if I was getting the right reading.
    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!

  13. #43
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    T-Gauges

    The "snap" or "T" gauges pictured in Kurt's earlier posting (just above) can be had at Harbor Freight for MUCH less.

    Flame on, HF-haters, but consider this: The real measurement takes place when you pull the gauge out of the bore and measure the width with an instrument of choice. It is helpful to use the piston-ring method of helping square this off, and something of a challenge to make sure that you're measuring at the widest point, but given that OVALITY is the big deal, here, you can get a plenty good idea of the "next step." As Kurt has suggested, before spending a lot of dough I'd personally verify my readings by paying a machine-shop a few bucks to measure with absolute accuracy.

    Overbore of 1000cc machines is usually not recommended.

    Walking Eagle
    Last edited by Walking Eagle; 01-22-2013 at 05:39 PM.

  14. #44
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    I used the telescoping gage set to remeasure the cylinders, but get quite a bit of variance. I'd measure the same part of the bore 2-3 times and get differences of 0.02-0.05mm. Near as I can tell, it's likely the inaccuracy of the digital caliper I have (from Harbor Freight). I'd first zero the readout, make the measurement, then go back to zero and find the readout wasn't zero. I could never get it to start at zero and go back to zero. Oh, well...

    Next, I'll take the cylinders to machine shop and get a professional reading.
    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!

  15. #45
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    Pulled the pistons and rings off today. Using the snap ring pliers was easy to free up the wrist pin which pushed out with a thumb. I believe there is an orientation to the circlips...the internal ring of the circlip has a sharp side and a more rounded side. This is due to how the circlips are punched out of metal during manufacture. Installation is supposed to have the sharp edge of the circlip out or towards the cylinder wall...this helps them bit more according to some stuff I've read. In my case, I think I had them installed both ways...the last time I had this apart was BI or "before Internet"!!

    The picture shows the stack of parts for the right side. Not that I had put in Luftmeister 3-piece oil rings shortly after I acquired the bike...that's the three rings to the right. They consist of two thin outer rings with a somewhat corragated middle ring. I installed these because I thought I had excessive oil usage at the beginning. My oil usage was the same before and after the ring replacement...go figure!

    I'll be measuring ring gaps later on.
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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!

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