My First Bike: A broken 1980RT

Discussion in 'Airheads' started by tbg, Jun 5, 2013.

  1. kaput13

    kaput13 gasoholic

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    + 1 on disston's analysis.

    Based on what you show so far your diagnosis "main bearing went freeing the piston to tear the cylinder out" is probably correct but you will not know the full extent of the damage until you free the piston and the rod from the crank and do some other investigating. If the damage is contained to what is shown then you got off easy.

    Your bike uses circlips on the pins.
    #21
  2. tbg

    tbg Bike Destroyer

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    I'm getting a chance to take the piston off Wednesday, as I'll be home with the circlip pliers. However, looking ahead to the connecting rods, the Clymer says I'll need some "12-point special male socket?" The only 12-point I can find is a Toyota 1/2in:

    I'll try to post decent pictures of the block damage tomorrow.
    #22
  3. gegster

    gegster Adventurer

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    #23
  4. Plaka

    Plaka Brevis illi vita est

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    I got a set of 4 at a box auto parts store for like $6. I only needed the one size. They are a solid 1/2" (I think) hex shank about 3" long with the 12 point male tip. I hot glued one into a junky 1/2" x 3/8" drive socket and there is my tool.

    Look for a place that has the Lisle selection of special tools. Good quality and not too costly.

    Example (but look for a single):

    http://www.denlorstools.com/home/dt...0750_triple_square_12_point_bit_set_-_4_.html

    Do not throw the bolts away, you will need them. But mark them so they cannot be mixed up with new ones. They will never run in the engine again but you use them for your measurements. Put the new ones on the tentative shopping list along with the gaskets.

    That list is going to tell you the cost of some things, even if you buy nothing. Like the cost in parts just to R&R top end and rods. If you abandon the motor and get another, you can adjust the price of the one you are buying if you know the cost of, for example, checking the top end and rods.
    #24
  5. disston

    disston ShadeTreeExpert

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    Pay attention. Important stuff was already relayed to you but you missed it because you don't see what is coming up.

    #1...Buy only the good tool. It is strong enough for this job. It is called a triple square. A cheaper tool will sometimes break. Get the triple square socket from either Northwoods or Cycle Works. Both addresses are already in this thread. Do not try to remove the rod bolts with a socket that seems to fit "close enough". The proper tool fits. An improper fitted tool may ruin the rod bolt and it will then have to be cut out with a torch which will ruin the crank.

    #2...It is a rod big end bearing. Do learn the proper name for stuff because it will save money and time in the future. A main bearing is also on the crankshaft. It is what holds the crank in the engine block. The main bearings are important but they are not the same as the rod bearings. So far you suspect a problem with a rod bearing. The rods also have a small end bearing. It's where the wrist pin or gudgeon pin is.

    The rod bearings are easy to replace. They don't even cost a lot of money. But when they go bad there is a chance of problems with the crankshaft. It is the crankshaft that is the most concern at the moment. Get the piston off and the rod off the crank and you will be able to see the crank journal. Try to take a picture of the crank journal.

    Do not throw any parts away. You may need these rod bolts for temporary assembly but they will not be used in final assembly. You should mark them somehow, a dab of paint works well but you could also cut a small notch in the heads with a file. Entire engines have been ruined because somebody reused the rod bolts. Don't make this mistake.

    I know that there seems to be too much extraneous information sometimes. You will have to figure out what parts are real. You are in the big league with this level of engine repair.
    #25
  6. Plaka

    Plaka Brevis illi vita est

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    Mine is a Power built. Low end of mid quality...but not harbor Fright low end. I've used for years and years and years...starting to show a bit of wear. A better one wouldn't show any. But at $8 for a set of four I'm money ahead.

    http://www.amazon.com/Powerbuilt-648599-Point-Internal-Bit/dp/B002INV1TQ

    The Lisle ones are better and usually available locally:

    http://www.amazon.com/Lisle-60750-Point-Triple-Square/dp/B0002NYC0Y/ref=pd_sim_sbs_auto_2

    This one is plenty for the job @$4:

    http://www.amazon.com/Tools-2305-10...=1-6&keywords=12+point+triple+square+bit+10mm

    But as soon as you go to a 3/8 drive style you get bend over for another $10:

    http://www.amazon.com/Vim-XZN110-Tr...02YKJI34/ref=pd_sim_sbs_auto_1#productDetails

    Probably longer lasting but if it's just sitting in the tool box unused the money could have been better spent. If you're planning on making a living at it or get off on the pride-of-ownership thing, buy almost all Snap-On.

    Supply your own junky 1/2 socket and sticking it in with chewing gum saves quite a bit. I came across a homeless Crescent socket and splurged on the hot glue. I used it without for a long time. If I ever blow up the socket I could care less.


    The really junk tools may have a poor fit and that will beat up a fastener, even at the low torques these things see. I use better tools for the things I do a lot, they last. I use the junk for where they go in harms way and get used rarely (behind seat of truck). I also have a bin full of Husky and other lower mid grade sockets, wrenches, extensions, ratchets and whatnot. Score 'em at yard sales for a dollar or so a box full. Handy for dedicating to this or that. Like the 1/2" allen on my dedicated rod bolt tool.

    So..um..tell me how this broken rod bolt thing works again? I gather you mean stripping the splines somehow? And then not being able to drill it somehow? You don't have to easy out it--thing only engages the cap. Torch??? You know a guy named Tom Cutter? (as in, real well?)


    One important tool for this little job is a small towel. As you slide the cylinder outward you slip the towel in so when the piston/rod assembly drops free it don't ding the spigot hole in the block.

    A small deadblow hammer (go real cheap) and a careful touch is nice for freeing stuck cylinders. I have literally dozens of hammers. I actually used the solid lead one (legacy from my old MG) to smack on a wrench with the other day---just to use it. It had been years.

    As long as you know you're pulling the rod, leave the piston attached to it and take that apart on the bench.

    So not mix anything up in the slightest..not even switching a pushrod end for end. So lots of paper towels to wipe oil, baggies, tape, a sharpie, etc.

    Back at the thrift store (and yard sales) I score old bread pans, baking sheets, brownie pans, etc. Keep it under .50 ea. Real nice for segregating gooey parts as you go along. Easy to clean and store when done. I end up with a lot of little projects piled in them.
    #26
  7. tbg

    tbg Bike Destroyer

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    @gegster - Thank you! Took my brain longer than I'd like to admit in figuring out what a "male socket" was.
    @Plaka - The list idea is one I've already considered. I'm terrified of what the actual price may be, but I suppose knowing is better than spending without a goal. And thanks for the broke-mechanic tips; I'm making a royal mess of my borrowed-garage, so every little bit counts!
    @disston - I appreciate your candidness. Now I know that a fluted socket and a male socket are the same thing! I'll be sure to be as accurate as possible with naming conventions in the future. No need to mess anything up.

    Here's a picture of what I believe to be engine block damage:
    [​IMG]

    Unfortunately, Imgur seems to hate my poorly-edited image. I should be able to get the rods and head off on Wednesday. I'll report back then with pictures.
    #27
  8. disston

    disston ShadeTreeExpert

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    This comes up a lot. Posting pictures is a big help but it is often not the solution. You have to tell us what the picture is of and what we are seeing.

    It looks like I see a ding on the inside of the engine bore where the cylinder base goes? Will an undamaged cylinder still fit or be made to fit by hand filling the damaged area? If the cylinder is made to fit this way does it look like there would be a weakness?

    How about the outside surface. Is the area the base of the cylinder seals against still flat?

    After you get the piston off and the rod out it should be possible to see the damage better.

    Try to keep work area clean especially a borrowed space. Bring cardboard boxes, beer boxes or oil boxes work well, to put stuff in. Any spilt oil should be cleaned up immediately. Sweep the floor so oily dirt doesn't get ground in concrete. Kitty Litter will absorb oily spills.
    #28
  9. tbg

    tbg Bike Destroyer

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    I'm lacking the vocabulary and knowledge to describe this with any precision. I'd like to say a small cut parallel to the rod that has dug material out from the head. Damage that matches the pictures of the top cylinder head/piston head.

    Likely, what I'm describing is wholly inaccurate. 1: Yes a ding. 2:Yes, but I believe it may need to be re-bored. 3: No.
    #29
  10. Plaka

    Plaka Brevis illi vita est

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    That ain't damage, that's patina...

    That was the punchline to a raunchy farmers daughter jokem, but forget the joke itself.

    Looks like a trivial scuff on a completely non-critcal surface...dress it out with a scraper and forget it. The bite out of the cylinder base is likely trivial too.
    #30
  11. disston

    disston ShadeTreeExpert

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    Yes to what Plaka says. So far everything may be reusable. The parts will need more careful examination before being used.
    #31
  12. tbg

    tbg Bike Destroyer

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    Got the piston head out. Unfortunately, with the rod in the way, no useful pictures could be taken of the crankshaft. I did get a better look at the chunk I pointed out in my previous posts:
    [​IMG]

    That's a picture of the top-inner lip of the cylinder, taken from directly below. My apologies for the bad focus.

    Additionally, I think a little chunk may have been torn from one of the camshaft's teeth. Perhaps that is what derailed the piston?
    #32
  13. disston

    disston ShadeTreeExpert

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    Replacing a cam shaft is not as much trouble as a crankshaft. A cam pretty much just plugs in. A crankshaft has to have the free play adjusted by different size thrust bearings. On many engines if a journal is damaged they can be machined but on our Airhead engines if the rod journal or main bearing journal is damaged it is better to find another crank instead of machining the damaged shaft.

    So the big question is still the condition of the rod bearing journal on the crankshaft.

    You now have the cylinder and the piston off? And are waiting for the tool to remove the connecting rod?
    #33
  14. Plaka

    Plaka Brevis illi vita est

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    Really? What makes uour airhead cranks so very special? It's half a VW crank. No magic metallurgy, no exotic plating, nothing. it's a Plain Jane crank like a hundred million others.They make oversize bearings for a reason...
    #34
  15. disston

    disston ShadeTreeExpert

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    There are three problems with grinding an Airhead crankshaft. One...the radius in the corners of the rod journal are not always properly done. I don't know why this happens but it has and apparently continues to be a problem. Two...the crankshaft is hardened with a Nitride process. This needs to be duplicated. Is not always done. Three...the bob weights on the crank need to be removed for grinding. They often will fly off later because they weren't properly reattached.

    All of these issues have plagued Airhead crankshaft grinding. Maybe the proper shop doing the job with proper techniques could avoid these issues. It's been tried. I think a few have succeeded but it looks like there are more failures than successes.

    Maybe not impossible I agree but there are plenty of Airhead crankshafts available in the used market so this is the advised course. Get a used crankshaft in good condition. There is the hassle of having to now reshim for the different crank and this is above shade tree mechanics abilities usually but it can be handled by the proper mechanic.

    Here is another discussion of the issue(s);

    http://www.advrider.com/forums/showthread.php?t=644361

    This has come up before. If you want to grind your crank then please do. But I'd like to know so I'm not riding next to you when one of the bob weights flies through the engine block. :deal
    #35
  16. Plaka

    Plaka Brevis illi vita est

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    So take it to a shop that knows WTF they're doing? All sorts of people can screw up anything. You hear the horror stories and they make great and entertaining news. Everybody wants to hear about how something is or got screwed up. But the jobs that come out fine, no issues, etc.---that isn't news. No Oh-My-Gawd!!! factor. You don't hear about it.

    However I don't know the cost difference.
    #36
  17. disston

    disston ShadeTreeExpert

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    Well I think it is a cost vs. reliability issue. You are right Plaka, that people seldom report what the fix is. They are too busy riding. :lol3 That might be why there seem to be more failures than successful grindings. But the used market today has plenty of crankshafts. I have noticed an increase in prices but that like most used parts issues is a matter of how much in a hurry you are.

    If you have the proper tools the novice even may reshim the crank but it's not for everybody. And the dial indicator and a few other things are not really cheap.

    This whole thing is putting the buggy before the horse. Let's wait to see how the crank journal looks. They are not always bad after one of these.
    #37
  18. Plaka

    Plaka Brevis illi vita est

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    You can actually use feeler gauges in place of a dial indicator. But you do need a bit of skill with them, and a piece of ground bar stock to work from. But you can get around even that with a piece of angle and a carriage bolt. A cheapo dial indicator will also work, and rig a stand. It will be accurate, it just won't hold up. For occasional use it's fine. We get spoiled here in the first world methinks.
    #38
  19. tbg

    tbg Bike Destroyer

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    Hopefully the crank journal is still intact!

    I believe the socket will have arrived at my workshop tomorrow, so I'm heading down to pull the rod and the oil pan.
    #39
  20. tbg

    tbg Bike Destroyer

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    Hit a bit of a hangup, ran out of time before I could find a solution:

    I've unbolted the rod, but it is wedged high in the cylinder, so I can't seem to get it out. I attempted to rotate the engine with an allen wrench, but the largest wrench I can fit only strips away the socket.

    Hopefully I'll have a chance to work on it some more tomorrow. Damn life getting in the way of my bike!
    #40