My Barn Twins

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

  1. fxray

    fxray Long timer

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    Hi Bill: Yep, there's nothing new under the sun (although this airhead stuff is new to me). Sorry if I'm slogging over old territory here. The main reasons why I put Paul's email in there was to say he's still selling them. So far, everything I've gotten has been high quality tools.

    With a first glance at some ot the tools from Cycle Works, it's easy to think a guy ought to just make his own. However, the prices are reasonable for what you get, and the tools are very good quality. By the time you round up the parts and make them, it is cheaper and easier to let Dan do it.

    Jim: I've been surprised by the odds and ends special tools for this airhead. I have the various Triumph special tools in a cheap plastic toolbox. I picked up an identical box for BMW stuff. It's almost heavier than the Triumph one already. Like Bill said, some of it could just be improvised, but . . . tool fetish strikes again! :lol3
    #61
  2. fxray

    fxray Long timer

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    Paint vs. powder coat -- they both have pros and cons.

    My first plan on this bike was to sand and touch up the rust and bare spots on the frame and miscellaneous parts and leave the tank and tins the way they came from BMW (plus 41 yrs of acquired patina) . Problem is that in the dead of winter, I have no good place to paint, and I'm not that good at it anyway.

    I talked to a couple of guys who paint bikes professionally to see if they wanted the work. They both told me I'd be far better off to find somebody to blast and power coat the frame. One of them had a friend who had recently gotten a frame done (almost locally). I visited the shop and was very impressed, so that's where my parts went.

    Harley Eades, who runs this one-man operation can pretty well do it all (vinyl graphics, multi-color powder, pin stripes in powder, metallic colors, basecoat/clearcoat, 6 levels of gloss, 6,580 colors from which to choose, etc.). He has a good background as an auto and motorcycle mechanic, has auto body experience, and has been doing powder coating for over seven years. His website (Like New Parts) is worth a look if you are thinking of having parts done -- maybe even if you're not.

    So I went ahead and stripped the bike down the rest of the way. I may be the only person in the world who doesn't much care for bike lift tables. I've used them, but I prefer to leave the bike on the center stand and sit on a little shop stool to work on it.

    With a strap on the center stand, this thing balances pretty well forward or back:

    [​IMG]


    With the front wheel off, I used my sky hook to lift the back end up and strip it:

    [​IMG]


    Then I set what was left into an old chair and levitated the front end to strip it down:

    [​IMG]


    Along the way, I made a lot of careful notes and took pictures of wire and cable routing, hardware, etc.

    So then it was powder time:

    I put bolts into all the threaded holes, including the swing arm pivot pin threads (I had to order those two bolts from Fastenal, but they only took one day and cost about 5 bucks for the pair). I ran a piece of all-thread through some rubber plugs, then snugged up some nuts and washers to keep blast media and powder out of the neck bearing area. The outer races are still in there, but I may change them later.

    The shop would have done all this for me, but I just wanted to be sure.

    I made up a couple of pages of instructions with pictures to go with the parts. This all seems kind of crazy, but the last bike I had done (different shop) came back with powder in some places where I didn't want it. It's not that hard to remove, but it's unnecessary to get it there in the first place.

    Example:

    . . . on the main frame, there are some places to exclude powder if you can. These are marked as "X" in the picture below. There are five holes, and one external lug. On the external lug, the end of the lug should be powder coated if possible, but leave the surface marked "X" in the picture bare steel.


    [​IMG]


    So, he blasted all those spots with aluminum oxide media and then protected them from powder. He did a great job of watching out for the details.

    I will paint the swing arm. It just didn't seem worthwhile to me to disturb the driveshaft which looked to be in good condition.

    The parts don't look too bad here, but they were pretty scruffy. They all had patches of rust and missing paint. paint.


    [​IMG]


    The threaded rods on the battery box were eaten literally halfway through with battery acid, so I cut them off and made new ones from stainless steel. I didn't want the thread area to rust, and I didn't want to wait for plating. I got somebody to weld those for me and then the powder shop did all but the threaded areas.

    The sub-frame struts that usually crack on the Airheads had one small split on one side, which a friend Tig welded. Also one of the headlight ears had a bad spot weld which I got redone. I did my best to smooth that out. Later I learned that there is high temperature epoxy filler that can be used under the powder if necessary.

    I didn't want the face of the chrome plated side lug on the headlight bucket either blasted to bare steel or powder coated, so I ground an old cupped washer from an automotive shock absorber to fit, then added a bolt. That mounting lug is riveted into place so it was easier just to leave it there.

    [​IMG]


    No muss, no fuss. The shop did all the blasting. The parts were done on time and at the stated price. They look very good. The man's first name is Harley, so what could have possibly gone wrong? :D

    Here are a few of the pieces after powder. All the parts are wrapped up and stored for now.

    [​IMG]


    I'll be blasting all my hardware and having a guy plate it in white cadmium before this starts to go back together.

    Edit: The last picture isn't too good. The actual parts look better. The battery box still has some rust pitting that I did not worry about smoothing out, but it isn't too bad powdered.

    For reference, I had 12 pieces blasted and powdered, for a total cost of US $384. My rule of thumb is that I wouldn't do it for someone else for that amount of money, so I thought that was a very fair price. :lol3
    #62
  3. ccmickelson

    ccmickelson MonoMania Supporter

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    That cracked me up. A man after my own heart.
    #63
  4. fxray

    fxray Long timer

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    With this lengthy post, I'll have my thread caught up to where the project actually is right now. Sorry I use so many words, but I figure you can scroll past and ignore it if you want. It's kind of record-keeping for me, and one or two other people may find the details helpful. :snore

    Here are a few more pictures as I decide what to do next. This thing is spread out about as far as it can be. If I were to quit now, it would be the perfect example of a basket case, so I'll try to keep plugging along.

    Before I pulled the cylinders, I checked the valve lash, finding the following:

    LH intake = .15mm
    LH exhaust = .11mm
    RH intake = .13mm
    RH exhaust = .10mm
    So, the intakes are on the loose side of spec, while the exhaust valve clearance is at about half of spec. I don't know if they were set wrong, or are closing up due to valve recession. I haven't removed the valves for a look yet.


    The rocker end-play was .04mm on both intakes, and less than that on both exhaust rockers (.04 was a no-go). I could wiggle them back and forth and see a difference in the oil film, so I guess that was proper.

    The pistons and wrist pins are out on one table:

    [​IMG]


    Some shots of the left piston:

    [​IMG]


    [​IMG]

    And the right piston:

    [​IMG]

    [​IMG]




    The right side seems to have a lot more carbon build-up, which I would attribute to the breather dumping on that side. Also, the air filter was nasty to say the least, so both sides were probably running rich.

    My old Starrett micrometers are graduated in thousandths of an inch and have no finger ratchets, so when I list dimensions to ten-thousandths, it is my best estimate based on feel and interpolating between the marks.

    I measured both wrist pins at .8660" (22.00mm) diameter, and 2.792" (70.92mm) long.

    I measured both piston wrist pin bores at .8666" (22.01mm). This may be a bit more suspect because I was using an internal snap gage and then measuring that with my micrometer. This is about triple what the book calls for as clearance, but the pins were a snug fit. I had to heat the pistons with a heat gun to push the pins out. I suspect my measuring could conceivably be off a tad. :wink:

    I measured both pistons at 3.5420" (89.97mm) at the base of the skirts. I haven't cleaned the tops of them to see whether they are stamped A,B, or C.

    The jugs are on another table:

    [​IMG]


    I borrowed a nice Mitutoyo dial bore gage, but of course I have no master set ring for it. I set it from the same micrometer that I used to measure the pistons, so at least I can be pretty sure of the clearance. The mic is there in the little vise, set to 3.5433" (90.00mm).

    I positioned the plunger against the mic anvil.

    [​IMG]


    And then wiggled the stem against the mic spindle. I was actually using both hands, but this gives the idea:

    [​IMG]


    Wiggling left and right and up and down to find the tightest position in the mic to set my zero point on the gage. So, maybe not perfect, but the best I could come up with.

    And here's the gage face, showing the graduations:

    [​IMG]


    The bores still have cross-hatch throughout. I had trouble getting a good picture, but the cross-hatch looks almost the same in the ring travel zone as it does below, only darker. Here I was shining a light inside to take a picture.

    This is the left cylinder:

    [​IMG]


    And the right:

    [​IMG]


    You may be wondering why the heads are still there, which makes for a strange picture. I did not try to separate the head gaskets yet. I want to seal everything up and bead blast the outside of the jugs and head. I figure the gasket will make a better seal against the glass if I don't disturb it. I'll be making up a wood bottom with some thick gasket material to seal off the spigot, and rubber plugs for the PRT's and inlet / outlet ports. Because of this, I don't know the A,B, or C, stamp on the jugs yet either. I think it is on the top surface of the jugs?

    Also, you can see the cylinders and pistons are still fairly dirty. I wiped everything down with paper towels before measuring, but they need a lot more cleaning.

    I measured the bores at top of stroke, mid-stroke, and bottom, both perpendicular to the pin and parallel to it. Subtracting the diameter of the piston skirt from those measurements, the largest piston clearance was .0038" on the left cylinder and .0039" on the right.
    Total variation among all the measurements was .0004" for the left side, and the same on the right side.
    Clymer has one of their boo-boos in this section. Here's a quote, "On 1970-1980 models, if the taper or out-of-round is 0.010 mm (0.004 in.) or greater, the cylinder can be rebored to the next oversize."


    The problem you may note here is that 0.010 mm = 0.0004 in., so they have misplaced their decimal point!
    The Factory Service Manual has this correct (0.010 mm = 0.0004 in.), but that sounds kind of crazy to me -- rebore if you find .0004" variation? I would be more inclined to believe a rebore was needed if there was over .004" taper or ovality, as opposed to .0004", but what do I know?


    All the bore size conversions from metric to inch are wrong in the Factory Service Manual, so I am a little untrusting of their numbers. Also, there is a lot of discussion about this amongst the ADVrider.com gurus.
    I need to ponder all of this for a while, but my inclination is that I may run a brush hone, clean the existing rings, and put it back together.
    I have all this on the back burner for a while now, because Spring is starting to appear. I've neglected the Harley all winter to play with the airhead, and the Harley needs a front tire before I can ride it. I finally got around to that, but I decided I really ought to do some other stuff too, like greasing and adjusting the steering stem bearings, new fork oil, new brake fluid, etc. With the front wheel and fender off, this was the time to do it.
    Here's my quick and dirty way to drop out the steering stem without taking anything apart on the top triple:


    [​IMG]

    [​IMG]

    My wife said it looks to her like a robot in traction at the hospital, and I have to agree.


    As always, I misjudged the job. I was just going to clean, grease, and adjust. Then I found that the top race looked like this (it's even worse than it looks in the picture):

    [​IMG]


    Still, that wouldn't be so bad, but I don't have any of the right tools to change out the bearings. Once again it's time to feed the tool fetish. They'll be here next Monday.

    So, stuff is spread out all over and I'm not a good multi-tasker:


    [​IMG]

    I spent too much time this past winter being lazy, but I told myself that time spent on ADVrider.com counted as research!
    #64
    Oms likes this.
  5. David4

    David4 Been here awhile

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    Ray, I read recently a method to happiness is to do less. That won't be your lot for awhile! :D

    Great job Ray!
    #65
  6. fxray

    fxray Long timer

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    Thanks, Dave. I hope that your snow has melted by now and you are enjoying that beautiful "new" T120.

    (Brief side note -- scroll past if you are a Harley hater): The Harley is back together with new steering stem bearings, rebuilt forks, new front tire, repacked wheel bearings, fresh brake fluid, etc. I even cleaned off the leftover bugs and dirt from last November.

    [​IMG]

    The tools I bought for this refresh job cost less than if I would have paid the dealer do the work, plus I no longer trust the local Harley dealer to do anything at all. As an added bonus, the tools will will work on the airhead even though the BMW uses slightly larger neck bearings.

    While I was working on the FXRS, I was still passively working on the airhead. All the while, this piston:

    [​IMG]

    was soaking in solvent in the parts washer:

    [​IMG]

    Every so often, I rubbed the top with an old toothbrush, gave it all a flush, and put it back to soaking again:

    [​IMG]

    Yesterday, I butchered up some scraps of 3/4" plywood to make this glued-up assembly:

    [​IMG]

    It doesn't look like much, but it will work in combination with these other "tools". There is a rubber gasket made by tracing around the genuine BMW base gasket. I used sheet rubber from the plumbing department at Menard's for this. I also cut four, one-foot pieces of 3/8" all-thread, and found some nuts and washers. The 5/8" rubber caps came from AutoZone and are a good fit on the PRT's. The #8 rubber plugs came from Ace Hardware. They taper enough that one size fits both the intake and exhaust ports. The used spark plug came with the bike, and the blue tape (next picture) I had on hand.

    [​IMG]

    All of this should protect the innards of the cylinder/head assemblies while they lose their accumulated crud in the blasting cabinet. The tape is over the rubber stopper plugs as back-up insurance (belts & suspenders):

    [​IMG]

    I'll let you know how that works out.

    Ray
    #66
  7. fxray

    fxray Long timer

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    It was finally warm enough this afternoon to roll the blast cabinet outside and take a shot at that cylinder assembly that I had trussed up like a Christmas goose (see previous post). The idea is to keep the blast media on the outside, and not the inside.

    It cleaned up pretty well. Here I had blasted it and then blown off the dust:

    [​IMG]

    [​IMG]

    I'll scrub it all down with hot, soapy water and give it a rinse. Then I'll probably shoot some Duplicolor on the barrel and head to keep the corrosion at bay. The valve cover will probably get some of the Rub 'n Buff. We'll see how all the colors match up.

    Next thing will be to blast all the hardware. Once I get that plated, I can start putting things back together.

    Ray
    #67
  8. therealbatman

    therealbatman "Godfather"

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    Impressive!
    #68
  9. chasbmw

    chasbmw Long timer

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    It looks as if you have blasted off all the plating from the pushrood tubes, getting them repainted without removing them will be difficult?

    How will you ensure that the rest of the engine and gearbox etc etc match the cylinders?
    #69
  10. fosterb

    fosterb Adventurer

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    so when you took the wood etc off, was there ant evidence of the grit inside?
    #70
  11. fxray

    fxray Long timer

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    Thanks! I was really surprised at how easily the crud came off. I started out with Plan A, which was a .22 caliber brass brush and some WD-40. I can testify that the blast cabinet is a whole lot easier and quicker.

    I did probably blast off whatever plating was left on the PRT's, but a lot of it was already gone and they had started to rust. I think I can get them covered O.K. with some hi-temp engine paint.

    I am going to paint the barrels and the heads, and will probably be using some Duplicolor engine paint with ceramic, maybe their DE1650 color, which they call Cast Aluminum or maybe their DE1615. I have used that before and been happy with it. It goes on easily and holds up very well. I'll cut a couple pieces of aluminum coil stock and paint them as samples to see what matches up. Whatever I use on the cylinders will probably also go on the wheel hubs. The rest of the engine is in Rub 'n Buff, which some people may not like. I still think it'll all look better than what I started with.

    I haven't taken it off yet. I will probably mess with it tomorrow. I'll wash the whole outside with hot, soapy water before I remove the protective stuff. If there is any media that made it inside the covers, at least it won't be imbedded in the surface to be released later.

    Ray
    #71
  12. fxray

    fxray Long timer

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    You know what they say about the best laid plans of men and mice . . .

    So, yeah, in spite of all my efforts, there was some glass inside when I removed the protective bits. I messed up by not sealing up the edges of the plywood. There were a couple chinks that blew out and let the glass get in. I was pretty bummed when I saw it, but I gave it a good cleanup with some hot, soapy water and a scrub brush. I'll hope for the best -- I probably worry too much anyhow.

    Anyway, I slipped the valves out for a look. I was surprised to see a shim under each lower spring seat cup.

    [​IMG]

    Here's a closer look at the shim.

    [​IMG]

    [​IMG]

    They both measure .048" thick (1.23mm), and have a scintered metal appearence. Is this common? A look at the fiche shows no shims. This bike only has 40k miles, and the valves don't look to me like they have been recut. Shims are usually used to fix low spring preload on recessed valves after a valve job.

    Anyone know if BMW did this, or is it an obvious sign of prior valve work?

    I also found the thick base gaskets, so I guess they were installed to lower the CR back when unleaded gas came on the scene. Coincidentally, the base gaskets are the same thickness as the valve spring shims I mentioned. I don't quite see any relationship, but it is strange that they are the same thickness. Shimming the valve spring would increase preload, but would have no effect on the valve's projected height.

    Some more pictures:

    Exhaust valve:

    [​IMG]

    [​IMG]

    Intake valve:

    [​IMG]

    [​IMG]

    More later. I have to go ride the little Honda.

    Ray
    #72
  13. fxray

    fxray Long timer

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    After 4 months of doing other stuff, I'm back to working on my R90/6 project. I've glass blasted most of the hardware and got it ready to go to the cad plater. Even though I probably won't ever put the fairing or engine guard (crash bars), and a few other bits back on the bike, I'll blast the mounting hardware and get it plated along with the rest. The price will be the same either way, since I'll be under the maximum for a batch.

    In that category, are these strange looking auxiliary footpegs that were on the bike when I got it. They are probably headed for my misc metal storage tub, but I am curious about them. Does anybody know if these are just JC Whitney junk from the mid 70's, or did BMW ever sell stuff like this? They are stamped from plate, and once had chrome on the foot rest and the main bracket. The rest of the hardware was zinc or cad plated. I've never seen any pegs like this, but I've never much been around BMW's either:

    [​IMG]

    There were a pair on the engine guards and another pair in back to give the pillion rider an alternate foot position. Anyone ever seen these before? Are they junk (that's what they look like to me), or are they priceless 41 year old relics? :hmmmmm

    Ray
    #73
  14. chasbmw

    chasbmw Long timer

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    Ray
    I'm pretty sure that those foot pegs are not BMW parts, probably US produced?

    Chrome plated foot pegs? Who thought that was a good idea.
    #74
  15. fxray

    fxray Long timer

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    Heh! Yeah, agreed. I guess I'll take the time to blast and plate the hardware bits and then put them in the bin with other metal scraps I save. It amazes me how often I rummage through that junk and find just what I need for whatever little project I'm on at the time.
    #75
  16. CafeDude

    CafeDude Ride to eat.....

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    The chrome plating shop. :-)
    #76
  17. fxray

    fxray Long timer

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    I'm moving along with my R90/6, even though it doesn't seem like it. I get kind of crazy dealing with the hardware bits. Here's my rather OCD process:

    As I strip the bike, taking pictures along the way, I put the hardware into plastic sandwich bags in what I hope is logical groupings. I label each bag by writing on it with a Sharpie pen. For this bike, I wound up with 42 bags of parts. When the time comes, I open one baggie and put the parts into the blast cabinet, counting the parts as they go in. One at a time, I pick up each bolt, nut, washer, whatever, with a pair of pliers inside the cabinet. This is kind of awkward while my hands are thrust into the big sleeved gloves of the cabinet. Holding the part with the pliers, I glass blast the crud off of it. It's important not to blast a hole in the gloves, hence the use of the pliers. When the part is blasted from all angles, I rotate it in the pliers, get a new grip on it, and blast the part that was covered by the pliers.

    Here's the HF cabinet I am using:

    [​IMG]

    It is the cheapest one from Harbor Freight, but I have reworked it so much to make it usable that I should have just bought a decent cabinet elsewhere. That is par for the course with HF tools. I put it onto a cart so that I can roll it outdoors to use it. I don't want the blast media inside the garage. I added a dust collector bag which just billows out behind the cart when in use. I also added lights, changed the piping around, replaced the glass, replaced the seals where they leaked the worst, bought and installed better sleeved gloves, modded the media drain opening on the hopper, and so on. I also wear a respirator while I use this cabinet. Working outdoors, I have to pick good weather days when it isn't too hot or cold and the sun isn't bouncing off the glass. Not a good setup to say the least. I have used the cabinet in wintertime, but it ain't fun.

    Blasting removes the rust and dirt, but it is also necessary to remove any remaining cadmium plating from the parts. If the old plating isn't removed, the new plating will be black and splotchy wherever the old cad remained. Here are some typical parts. As you can see, there is still cadmium plating but it has suffered. Other parts don't have as much plating left:

    [​IMG]

    It helps to have decent lights inside the cabinet to be able to tell when a part is done. Even so, I look the parts over carefully as I remove them from the cabinet. Sometimes they have to go back in for another round. When clean, they go back into their baggie and I repeat the process with the next baggie of parts.

    After all the bags are processed (time measured in days, not hours), the next phase is to empty each bag out onto a paper towel and take a picture of its contents. Here's a typical shot:

    [​IMG]

    Then I post-process the picture somewhat and paste it into a MS Word document, one page for each baggie of parts. Under the picture, I type a description of the parts using my own shorthand method. I include enough caliper measurements of each part that I can figure out later which is which. That's because they all have to be mixed into one batch for the plater. After I get them back, I have to find and identify each piece and put it back into its original baggie.

    The pages look something like this:

    [​IMG]

    The document for this bike is done -- 42 pages in all, and the MS Word count shows 2,313 words typed in there. My Triumph ran to 54 pages, so this airhead must be a little simpler machine, at least in terms of fasteners.

    When I think I'm all done, I make another sweep of the parts shelves. Invariably, I find forgotten parts that really should have been blasted, like the nuts on the petcocks that I had put in a box still assembled. I don't want to miss anything, because I will be making a 400 mile round trip to the plater. I don't want the parts lost in shipping and the shop I am dealing with only works with customers who pick up and deliver their own stuff. Missed parts mean another round of the above process and payment for a second batch at the shop. Yikes!

    There are ways around all this:

    * Buy a home plating copy-cad kit from Caswell or make up my own plating system from other sources. I know that would be smart, but I just haven't gotten there yet.

    * Buy all new hardware. That's too expensive and I want to keep as much original content as possible.

    * Clean the parts but don't plate them. Fake it with aluminum paint. I just can't bring myself to do that on a large scale, though I have done that with a few individual pieces on my other bikes.

    As if that isn't all bad enough, I lost my sidekick. Here he was helping me sort out my TR6 parts after they came back from the plating shop:

    [​IMG]

    We lost him to illness a couple of months ago, so I'm on my own. I miss his help.
    #77
  18. JGT

    JGT Been here awhile Supporter

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    Great looking project and nice pictures!

    My advice, learned the hard way, is that if you choose to hone the cylinder and re-use your pistons, get new rings. I tried re-using rings on a worn /5 cylinder and had very high oil consumption which finally went away after honing and installing new rings. They don't cost much if you do it right the first time.
    #78
  19. fxray

    fxray Long timer

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    Thanks for your comment. Yes, the next step will be to get back into the engine work -- cleaning and measuring the rest of the internal parts, honing the cylinders, perhaps buying new rings, maybe head work, maybe timing chain and sprockets. I stopped with all that to get my fasteners done. There is a lot of stuff ready to be bolted back together but it has been held up waiting for hardware.

    I'm kind of torn about the rings. When I had my little CL350 Honda apart to replace the cam chain and tensioner, everybody told me it was stupid to re-use the old rings. I removed and cleaned and measured them, ran a ball hone in the cylinders, and put them back together. It uses no oil, runs great, no complaints. I haven't even bothered to check compression because it works so well.

    This airhead would actually have less involved to pull the jugs back off if necessary than on that Honda. I haven't decided yet, but I may give the old rings a try. If it doesn't work out, I'll post it here and you can tell me later that you told me so! :D

    Ray
    #79
  20. Steve in OC

    Steve in OC Been here awhile

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    Location:
    New York
    I'm really enjoying this thread. It's great to see top-notch work.

    Re: blasting and re-plating fasteners. I love to see refurb and re-use of original hardware.

    Re: blasting the cylinder heads and jugs: They look great! Like new. I guess it was all but inevitable that some media would get inside, though. I was kind of surprised that you were holding out some hope that it wouldn't! I don't have a blast cabinet or a pro parts washer, etc., and my top end was fairly recently rebuilt (don't want to disassemble it anytime soon), so I made do with some aluminum jelly, then soap and water, and some black high-temp paint on the jugs. It looks good enough for a daily rider, but probably not good enough for a frame-off like you are doing.

    Re: re-using piston rings: I'd go with the conventional wisdom and replace them. It's a major wear point, and they have forty thousand miles on them. Isn't a new set only about $100? On the other hand, if you don't mind tearing the top end back down if it smokes or has low compression, why not give the old rings a try. The only downside I can think of would be the time it would take, and wear and tear on the studs/fasteners.
    #80