My Barn Twins

Discussion in 'Airheads' started by fxray, Feb 26, 2015.

  1. bpeckm

    bpeckm Grin! Supporter

    Joined:
    Apr 2, 2008
    Oddometer:
    7,904
    Location:
    Road Island
    If'n I had to rank threads by the "information per page", this one would have to be right at the tippy top... to say nothing of ranking by "tools I've never heard of"......

    Good stuff, m'man!

    :-)
  2. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Thanks for the comment Bob. You could have just as easily said that I run on way too long without saying anything important. :lol3

    I'm not an expert by any means, but I have been told that it is important for the valve springs to have the proper force as per spec. One reason is to prevent valve float at higher rpm's (probably won't be a factor for somebody like me), but also to make sure the valve closes well enough to properly transfer heat from the head of the valve to the seat. Hence all this fooling around. Besides, it's kinda fun.

    Ray
  3. Disston

    Disston ShadeTreeExpert

    Joined:
    Aug 31, 2009
    Oddometer:
    15,573
    Location:
    Silver Spring, Md
    It's the first time I've seen somebody try to use a valve spring height gauge on an Airhead. I'd like to know which gauge does fit but you came up with a good work around.

    I think the purpose of measuring the height is to prevent binding of the springs from them being compressed to the point where they can't compress anymore. At this point the cam will be wiped or the pushrod bent.

    This thread is the best in Airhead tech.
    bpeckm likes this.
  4. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Yet another airhead tool -- give yourself a treat if you know what this is for:

    Yep, that's right. It's an adapter for a leak down test. My exhaust valves were pitted enough to let some acetone leak past the seats, so my buddy with the valve cutting tools said he would touch them up. First, he wanted me to make up this test plate. He likes to hook up a leak down tester to the head once he thinks he is all done with the valve job. It's better than waiting till the engine is back together and then finding the problem if there is one.

    "Make it out of 1/4" or 3/8" plate if you have it," he said.

    So, of course, 3/8" was all I had. That's a lot of cutting with a hand powered hacksaw, and I don't have a bandsaw!

    Well, actually, I just had to cut the corner off the plate.

    O.K., so I used a Sawzall -- it still took a while.

    [​IMG]

    This is just a dry fit to make sure the bolts line up. I have a piece of 1/8" thick rubber sheet coming from McMaster-Carr. I doubt if my steel plate is flat enough to seal properly without a nice, squishy gasket. I made a plate like this to fit my Triumph head when we did those valves, and it worked well. That bike has about 5,000 miles on the valve job now and is going strong. I hope this one goes as well.

    Now a question for you airhead gurus. In reference to valve inspection, the Clymer book says, "Unevenness of the contact surface is an indication that the valve is not serviceable. The valve contact surface can not be ground and must be replaced if defective."

    In contrast, the FSM says . . .

    [​IMG]

    So who's correct? I know that my CL350 Honda valves have some sort of thin (maybe stellite?) coating that precludes grinding them. You can do it, but they will soon fail in service. How 'bout BMW? Another factor is that I have no idea if these are the original valves. My inclination is to touch them up. My friend who will be doing this says that he doesn't trust new valves out of the box without taking a light cut.

    Ray
  5. SuperDave67

    SuperDave67 Been here awhile

    Joined:
    Jan 23, 2015
    Oddometer:
    258
    Location:
    Rockville, MD
    This is a great thread. You guys really know your shit :-)
  6. Pokie

    Pokie Just plain Pokie.

    Joined:
    Apr 4, 2013
    Oddometer:
    3,596
    Location:
    Fort Collins, CO
    Yes, I know mine, and what you just stepped in wasn't mine! I think.
  7. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Pokie, what do you think about grinding those valves if the thickness is still O.K.? I don't want to order new ones if I don't have to.
  8. Pokie

    Pokie Just plain Pokie.

    Joined:
    Apr 4, 2013
    Oddometer:
    3,596
    Location:
    Fort Collins, CO
    I would probably try giving it a light lap to see if it improves. After a few minutes if the situation hasn't been resolved, either the valve needs to be touched up or replaced and possibly the seat cut.

    When removing the valve, after the spring and collets are off, if the valve doesn't slide easily down the guide, don't force it. Instead, file the burrs that have kicked up at the collet grooves. If you force the valve out without filing down those burrs, you WILL damage the guide.

    When you have the valve out, check the guide for wear. If the guide is loose, this would be a good time to replace that as well. A loose guide can cause the valve to leak. With a loose guide the valve keeps wandering to the side that has the rocker thrust, causing the seat to go a bit out of round. This condition is very hard to see because it's quite minor. If it was large enough to actually see, the motor wouldn't run.
  9. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    O.K., thanks. I have already had the valves out and measured the guides with a small dial bore gauge, as well as measuring the stems with a mic. All looks good there. I think the only issue is the pitting on the exhaust seats. We'll go easy.

    I guess my main question is whether BMW used any special coating on the valve itself that could be damaged by a light touch-up on the grinder? Seems funny that Clymer says don't ever grind the valve, and the BMW manual shows a picture of it being done. Maybe that's the answer right there -- the Factory Manual saying it's O.K.

    Ray
  10. Disston

    Disston ShadeTreeExpert

    Joined:
    Aug 31, 2009
    Oddometer:
    15,573
    Location:
    Silver Spring, Md
    I have seen reports of valve faces that were run for all those years on leaded gasoline that wouldn't hold a valve adjustment after being ground. The theory was that even after the lead was taken out of gasoline there was some still imbedded on the valve face and it was the loss of this tiny amount of lead on the face that then caused rapid (by just a little bit) erosion of the valve when back in service. Eventually they did stabilize tho.

    My personal experience was something like this. After lapping the valves a few years ago I had to reset the valve lash more often than seemed normal. I used a lead substitute for awhile but only a few months. I haven't used any such products now in several years. Eventually my valves also stabilized. I am due for a head torqueing and valve adjustment soon (been about 5000 since valve lash and 10000 since head torque) and will be looking for anything out of the ordinary as usual.

    I don't always put valve lash off for 5000 but nice to know it runs OK for that long.

    I am on my second set of heads and plan to send the first set off someday. I replaced the exhaust valves on the Ebay set of heads I bought as my second set of heads.

    Other than my experience with what may have been the loss of lead on the valve faces I've never heard of a special coating.
  11. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Thanks for the input, disston. We will go ahead and dress these valves. He wants to do the job next Sunday.

    Meanwhile, I wandered downstairs yesterday and gazed at the pieces of the jigsaw puzzle that used to be an R90/6. It isn't quite like buying a basket case that was packed away years ago by some stranger, but at my age, it is similar. Actually, I have it pretty well organized. It's time to start piecing it back together. I sorta wish the wheels, front forks, and swing arm were all done up. They still need work. I didn't powdercoat the swing arm, so it needs to be sanded down and painted. Nothing here is a big job, I just need to get started. Spring will be here before we know it!

    Ray
  12. Disston

    Disston ShadeTreeExpert

    Joined:
    Aug 31, 2009
    Oddometer:
    15,573
    Location:
    Silver Spring, Md
    It's much better if you can be fairly certain all the parts are there. When buying a basket case you can't be sure how many parts are missing.

    Start on it tonight. :1drink
  13. bpeckm

    bpeckm Grin! Supporter

    Joined:
    Apr 2, 2008
    Oddometer:
    7,904
    Location:
    Road Island
    Yes.... a litter bit every day, and it's amazing how it keeps going... I too am looking forward to doing some assembly, I have a couple of bins, a bunch of cardboard boxes, and well, you know how it goes... the anticipation of putting newly-painted stuff together with assembling stuff.... oooooooh! :gdog
  14. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    It'll be great to get the heads finished and get the engine sealed up. While I'm waiting on that, I messed around with a little assembly work to get back into it. You have to start somewhere. I found the foot-pegs on the shelf, gave them a little more cleanup and put them back on. I had forgotten about the RH peg being about twice as long as the LH one. Gotta go with the flow -- the RH cylinder is further back, so this keeps it all in proportion.

    Substituting a different leg on the bike lift gave me room to put the side stand back in place. It seemed like it would be easier to do that now instead of later. I've been through all the shelves and cannot find that bumper pad for the side stand anywhere. It'll turn up.

    [​IMG]

    When I got my cadmium plating done, I included the springs. I know that some people think this is a bad idea due to the risk of hydrogen imbrittlement, but I did the same thing on my Triumph springs and they have been just fine. In fact, I plated the springs for the front suspension on that bike. So far, so good. There is more danger of hydrogen imbrittlement with nickel plating (preparatory for chrome), than there is with white cadmium, or so I was told by a long-term plater.

    To plate the springs, I put them on some little stretchers that I made up. This separates the coils and lets the plating reach all the surfaces in between:

    [​IMG]

    So they came up pretty nicely. I also plated the side stand itself with white cadmium:

    [​IMG]

    The pillion pegs weren't too bad from their time in the barn. The rubber was still in nice shape, but there was some rust and grime. The black bits got turned in to be blasted and powdercoated:

    [​IMG]

    [​IMG]

    I thought that as long as I was in the mode, I'd see if I could make the plated parts look a little better. I started by grinding off the mushroom ends on the rivets. Then I blasted the individual parts with Skat Blast, and took them to the plater with the rest of the stuff.

    Here's one of them stuck back together and the other one still in pieces:

    [​IMG]

    I figured I'd have to put a bolt through where the rivets were, but then I decided to give the rivets a try. They were blasted and plated, so why not? I came up with a 3/16" and a 1/4" ball bearing. The 1/4" one fit better.

    [​IMG]

    [​IMG]

    Into a vice, and a little squeeze, and the end of the rivet is swaged back out.

    [​IMG]

    It looks a little insecure, but I don't believe it will come out. I'll keep an eye on it. All it has to do is keep the rivet in place, there's really no force trying to remove it.

    [​IMG]

    So those odds and ends are back in place.

    [​IMG]

    I also tried to save the rubber mounts for the battery box and the fuel tank. The rubber was still good, but they were rusty. I just blasted them and had them replated. They came out pretty nice and were not harmed at all by the plating process. The rubber is still soft and pliable:

    [​IMG]

    Hey it's a start with all these little bits and pieces . . . and all afternoon I've had this earworm (I think that's a German term to go with this German bike). Is anybody else old enough to remember 1964? It wasn't so long ago -- that's the year of my TR6. :lol3

    bpeckm likes this.
  15. bpeckm

    bpeckm Grin! Supporter

    Joined:
    Apr 2, 2008
    Oddometer:
    7,904
    Location:
    Road Island
    Bits & Pieces .... Classic DC5! .............and what a hoot to see the video with some "time and perspective".... those were simpler times, eh?

    Bike is unbelievable, it's going to look so good that you may not want to ride it!
  16. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Hi Bob,

    When I was looking at those foot-pegs yesterday, I found this picture you had posted at one time to explain why the RH peg is longer. It is a very illustrative shot, so I shamelessly stole a copy of it:

    [​IMG]

    I e-mailed it to my buddy who used to own my R90/6 and asked him if he had ever noticed that peg offset when he was riding the bike.

    He replied a while ago, in his normal style. He said, " . . . strange that I never noticed it myself. Of course, I've never been one to put his right foot forward."

    He can always make me chuckle, and truer words were never spoken.

    Ray
  17. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Went to my friend's shop yesterday to touch up the valve seats, but we hit a snag. His collection of Neway solid tapered pilots stopped just one size too small for the valve guides. The pilots come in graduated sizes, with a very slight taper over the length that fits into the valve guide. The properly sized pilot should be a snug fit into the guide. If anybody is interested, there is a Neway instruction .pdf on-line here that shows the process. He is going to order a couple more pilots in the next two available sizes, and we will try again.

    We did (well, HE did) go ahead and make a cleanup cut on the face of each valve. They came up nicely -- no pictures yet. He's a perfectionist, and I enjoy watching him work.

    Ray
  18. Pokie

    Pokie Just plain Pokie.

    Joined:
    Apr 4, 2013
    Oddometer:
    3,596
    Location:
    Fort Collins, CO
    I enjoy watching other people work too, it's so much LESS stressful.
  19. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    You bet, Pokie, and that's exactly why I spend too much time on here looking at other people's build threads, though it is educational.

    I did get a little done today. Defying all logic, I turned my back on the engine for a while and attached the rear frame and the seat with its hinges.

    [​IMG]

    Then I fooled around with the seat latch / lock and got it back together. It had been all rusted up, so I took it to pieces, blasted the parts, and got them cad plated. I have all the keys for this bike, and that seat lock works fine.

    [​IMG]

    I know I'll need to partially remove the grab handle when I put the side cover on, but right now I'm just sorting things out.

    The rear fender is loosely in place. I need to get the rubber flat washers that go under the steel flat washers. You can see the paint isn't exactly perfect, but it is original and I plan to keep it. I am liking the looks of the powder coated frame though. It was pretty nasty before.

    Next up, I guess I'll work on the parts inside the front cover, or hang the lights on the back end and do the rear frame wiring harness.

    [​IMG]

    Ray
    bpeckm likes this.
  20. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,388
    Location:
    Illinois, USA
    Some people dislike the 1974 BMW as a problematic transitional year, or so I have read. For example, it's the first year of:
    • /6 model
    • 5 speed transmission
    • front disc brake
    It's also the last year of:
    • nice /5 style switch gear
    • kickstarter fitted as standard
    • alloy rear turn signal housings
    O.K., so stop right there! What were those Germans thinking about when they put black plastic turn signals on the back of their motorcycles? Go Figure! That right there would make it worthwhile to get yourself a '74 model, or at least the lights off one. :lol3

    [​IMG]

    So that's my little rant for today. I fitted the rear lights and wiring harness just now, and I think I like the looks of it all. By the way, I have read of people cutting the wiring harness where it enters the rear frame. There is never a reason to do that! It is very easy to slide that section of harness out of the frame and then back in when the powder coating is done.

    Pictures of the connections inside the tail light are helpful, though. I was glad I had this and a couple others from my teardown pictures:

    [​IMG]

    There was some work involved in those big (some would call them ugly) side reflectors. They were not on there when I got the bike. I would imagine the original owner was pissed at having those big, ugly, government mandated reflectors on there and they probably bit the dust the first day he had the bike. Or . . . he may have just taken them off when he put the Krauser bags on there. Anyway, they were gone.

    I think they are NLA from BMW, at least they are not listed on the fiche anymore. But, a friend was parting out an R100 last summer that had a pair. They were pretty nasty and he couldn't get them off the license plate bracket. Turn the nut on either one of them, and the stud just spun inside the reflector. I think I gave him $10 for the whole bracket, and he felt bad about taking it. He was just going to throw it in the trash.

    I remember spending a couple afternoons last summer removing and cleaning those things. I filed a couple tiny flats at the top of each little stud, so that I could grip the stud with pliers and remove the nuts. PB Blaster helped. I packed a little JB Weld at the base of each stud. After it set up, I ran a die nut down each to make the threads work easily. I got new stainless nuts to fasten them to the bracket, and chrome acorn nuts to hide the damaged threads at the top of each stud. I polished the alloy frame on the reflectors. After the bracket was blasted and powder coated, the reflectors went back on. Tonight, they are finally back on the bike, sort of like the way it left the dealership over 41 years ago.

    [​IMG]

    Is this the very definition of A.R.? Oh well, I like 'em on there!

    Cheers!

    Ray