Ontic's 1981 R80G/S build-up thread

Discussion in 'Airheads' started by ontic, May 24, 2011.

  1. ontic

    ontic

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    I've been on the lookout for some old bikes, even just to cut up and practice welding, but as soon as you start looking you can't find them.

    Back from the garage,
    I didn't get the swing arm off- realised I need to grind down a 27mm socket and I don't want to ruin my good Bahco set. Going to have to find a sacrificial socket for the that job.
    However, when I took the rear wheel off and shook the swing arm side to side (as per clymer instructions) I could no longer detect any movement- maybe all this wobble is actually all in the final drive...
    going to have to google about rebuilding that, not something I am looking forward to.

    a few more photos (excuse the mess, the incredibly bright work light and the mobile phone photos:lol3)

    what was dented is now not, all primed and silky smooth and fair, still don't know what colour it will end up.

    [​IMG]

    had a couple of goes of mocking up the left side subframe reinforcement, this is the second attempt with only one quite sever bend, which looked a lot better than one with more bends

    [​IMG]
    [​IMG]

    and another angle on the right hand side one
    [​IMG]

    both left and right braces are going to have tabs welded on where they cross the pannier frame, which will also have tabs welded on so they can bolt together and brace each other.

    Although it was bothering me at first, I am sort of getting into the whole asymmetric thing, there is not much at all symetrical on this bike, so why should my mods to the subframe be?

    and with the rear wheel off, here is a shot from underneath,
    the whole exhaust system is stainless, except for that small section after the Y piece up untill the muffler which is just mild steel and has been painted in header black.
    [​IMG]

    cheers,
    #61
  2. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    With your rear subframe reinforcement, are you welding the long brace down to the lower part of the subframe where it bolts to the mainframe. I think Airheadwrangler (an R80ST) had his subframe break just behind the grab loop. If you are reinforcing it where it bolts up at the bottom, then the top attachment point will still have the same amount of stress being applied to it...i.e. still weak. Your brace will help reduce the leverage of the tail section, behind the grab loop and transfer stress closer to the tank mounts and add stress to the lower subframe mounts down by the foot pegs.

    Just a thought for you, I don't know if it's enough, it might be.
    #62
  3. Airhead Wrangler

    Airhead Wrangler Long timer

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    I had one of the luggage mount plates on my original subframe break off. I then installed a R100GS subframe and it's been fine to this day. A friend of mine had his R100GS subframe separate behind the grab loop, but it was due to some VERY rough roads, VERY heavy loads, and a lot of play in his luggage mounts. They knocked a lot and led to a fatigue failure
    #63
  4. ontic

    ontic

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    Thanks guys,

    OLH, yeah your description was accurite. From the bottom where it mounts to the mainframe up to that curve near the end of the subframe.

    I'm far from calculating loads or stresses or anything like that, and I am doing this because I am quite often guilty of carrying a lot weight, and I plan to thrash this bike- this is basically a preemptive seat of the pants add in a bit more here and hope for the best...

    I think it will be good enough or at least better.
    I'm pretty happy with these mock-ups, now 've just got to find some decent cold drawn seamless tube to make up the real versions.


    There is never enough hours in the day.
    I've been reading through the clymer again trying to figure out a few things. I really want to finalise my motobins order.

    Maybe someone can help with advice or link to where this has already been discussed.


    Basically this bike will be stripped down to frame components and built back up. For the engine, aside from taking the top end off and on, I'll probably only be going as far as the timing chain unless other problems turn up. I also don't plan on cracking open the gearbox.
    Has anyone ever written up a list of the minimum parts needed to do this kind of thing? I'm getting obvious things like motobins 'complete' engine gasket kit, but what about things like those one use 'stretch' drive shaft bolts?
    Surely there's a small pile of little things like this that are needed (things I don't know about until I need them and then have to put in another order!)

    Also, I think I am going to have to bite the bullet and accept that I will have to look a bit harder into the final drive. I'll be getting new swing arm bearings and pivot bolts, just in case, but there is simply too much play in the rear end, and particularly the final drive to ignore it.

    I've read this thread and I am confused...
    http://www.advrider.com/forums/showthread.php?t=625235

    I have an early G/S, is this play to be expected and is it OK?

    I can see on motobins as suitable for my G/S:
    crown wheel output bearing
    crown wheel input needle bearing (up to 1985)
    Pinion input ball bearing
    Pinion needle output end. bearing

    Thats a lot of bearings and not cheap either. Is this a matter of pull it apart and see what needs replacing or should I just pony up for a full set of bearings...

    The clymer seems to deal with the final drive as 'All Models Except 100GS' in one section. With a skim read I've seen no real mention about anything G/S specific. Feeling a bit confused about this.

    Cheers,
    #64
  5. ontic

    ontic

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    Ok,
    apologies,
    instead of going to bed like I should have I had to go out to the shed to get oily...

    Something wasn't jelling right.
    The side to side play I was feeling last night in the rear end and what I have been worrying about- I hadn't felt that before... but I'd looked for it...

    So I bolted up the wheel again and properly torqued it up (there's the trick!:lol3) and could no longer detect any side to side play in the rear end while holding the wheel in the 3 o'clock position. What I could still detect, like I did before, is the play in the final drive when gripping the wheel in the 12 and 6 o'clock positions.
    So, just like AW described in that thread linked to above, no play at 3 and 9, and play at 12 and 6.
    I am not sure about the measurement of the play at the rim, I'll have to try to carefully measure it at a later date. It feels like it would be over 1mm, just because I can so clearly feel it, but then sometimes things like that can be deceptive.

    I just drained the final drive oil and on the magnetic plug there was only a little bit of very healthy silky metallic paste- nothing indicating bearing destruction or anything else alarming (I've been through that on the transfer case in my BJ42). The oil was quite used and dark but still clear and voluminous.

    So, depending on the amount of play I measure, I am leaning towards thinking that the final drive might just be OK and that this 12-6 play is nothing to worry about unless it gets larger?

    For interests sake, what would be the cause of this 12-6 but not 3-9 play? Easy fix, or PITA fix?

    to bed for real this time,
    #65
  6. Rucksta

    Rucksta SS Blowhard

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    If the lower shock mount is sloppy it can present as play at 12/6 absent at 9/3.
    Press your thumb on the bottom of the shock body and across the mounting bracket on the swing arm.
    Now give the final drive a waggle up and down.

    Do you detact any movemnt between the shock body and the mounting bracket
    With luck that will be all it is.
    If the slop is present get rid of it and check for final drive play again
    Hopefully it will be gone.

    Next test give the wheel a spin forwards then backwards.
    Is there a difference in the rumbling noises?
    Big difference has always meant bearings for me.
    With an even noise in both directions I usually get by with reshimming the big bearing but have alwways had the 12/6 & 9/3 play together in this case.
    #66
  7. Airhead Wrangler

    Airhead Wrangler Long timer

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    My best guess as to why there is 12/6 play and no 3/9 is that the cover that holds the outter ball bearing gets a bit worn due to wheel impacts and what not they're ALL in the 12/6 direction more or less. If that cover wears a bit, no amount of shimming or even new bearings will get rid of the play.
    #67
  8. Padmei

    Padmei enamoured

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    i'm liking what youre doing Ontic. I know where you're coming from with the assymetric thing- it involves bending your mind a bit.
    I'm doing kinda similar stuff to mine however with advice from those with much more experience submitted the final drive & gearbox to experienced mechs.
    As far as the motobins order - any plastic bungs missing? A spare set of final drive screws definitely, rubber gaiters for final drive, spare crush washers, spare final drive & gearbox output seals?
    #68
  9. ontic

    ontic

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    Sorry for the late replies, I've been flat out busy this weekend and yesterday and unfortunately none of that involved anything motorbike related. (Been cleaning, painting and working on my boat getting it ready for sale)


    Thanks, as a general rule that is something I always need to be reminded of.
    I should have time to try everything you very helpfully suggested tomorrow night.


    Thanks for pondering an explanation. Without having a strong knowledge of the parts you are talking about yet, it sounds reasonable.
    With play developing like this though, I would wonder why the process wouldn't continue and even accelerate as the play increases?

    Thanks mate, yeah, there's definitely a bit of mind bending involved. I've been following your thread on Schmidt and love what you are doing.
    Also, thanks for the parts suggestions. I was already getting the rubber gaiters for the final drive but the rest will go on the list.

    My gearbox feels pretty good. I've also got two spare gearboxes I could swap on if problems with this one developed. With this box I've hit a few false neutrals at times but I believe this is being caused by the incredibly worn and sloppy shift linkage (the bushing has had it and everything just flops around!)- aside from that the gearbox feels great.

    And about bending, end of last week I sourced some nice seamless 16mm hydraulic tube for the subframe reinforcement. Just mild steel I think, but compared to the same wall thickness and OD seamed tube I've been using to mock up with it feels a hell of a lot better.
    I've got enough to do the luggage rack as well but to save a little weight I may very well get the same thing in a thinner wall for this application as this thicker stuff is probably a bit overkill for the luggage rack application.

    On friday past I spent a few hours cutting and bending and starting to grind/file and fit-up the subframe reinforcement pieces. As a TIG welder I am pretty much useless unless my metal pieces fit really well together.
    Fitting these bits properly at their odd angles of joins is taking forever!
    I need a damn dremel and a pile of those little mini drum sanding things.

    I'll try to fit in some more work on the bike this week, but really most of my spare time over the next couple of weeks will be heading out to the boat and working on it- a lot of this trying to get the F%*#ING 80 year old British inboard engine to run reliably.

    Cheers,
    #69
  10. Sibbo

    Sibbo Been here awhile

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    :D:D
    Have fun !!! It's a 2 stroke too eh ?
    #70
  11. ontic

    ontic

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    thanks mate, yep, twin cylinder 2-stroke. Last time I wrestled with this bloody engine I got it running OK- the carby is very simple and has minimal adjustment- I cleaned out the choked up header and got a better seal between the carby and the block, all horribly difficult tasks involving working space- having removed and put back on the carby throttle linkage the idle and starting settings were bit off but it was finally starting and running OK. This time I went out and there was no spark. So the next day I got another Lucas SR impulse magneto out of my spares (Lucky!) and swapped it on. Nice bright spark, timing seemed about right (just after TDC). Trying to adjust the timing is a RPITA.
    Along with 5 liters of fresh premium I took a near new fully charged bike battery out and spent the day hand cranking to get the flywheel going and then pressing the Dynastart button. I also liberally used about a 3rd of a can of 'start ya bastard' ether spray.
    Occasionally it backfired a litte, and a fair few times it almost ran. Almost. Clean the plugs, air the engine, try some different settings, try again... and again and again all day. My back still hurts from all the cranking.
    No joy.
    Next time I am going to lug out the battery from my truck with the hope that the extra speed of turning the engine over will get it to fire. It felt like a bit more crank over speed might have done it. I have a feeling that once I get it running it will burn out the damp old cobwebs from the engine and will actually allow me to tune the carby on the fly in order to get the settings a bit better.
    If this doesn't work then I am going to have to try to free the seized-up tiny little slotted screw on the end of the maggy drive shaft, facing away from me, right up the back of the engine in the really inaccessible bit, and start blindly playing with the timing a little bit (the timing marks on my flywheel are rusted off:lol3)

    It is such a simple engine, and the people who get them running well can start them with a hand flick of the flywheel. Mine has never done that and has been the bane of my boat ownership- but no doubt it is something really really simple.





    Anyway, back to bikes.

    I just tried Rucksta's suggestions and there is no perceivable play in the shock mount or anything else other than the final drive.
    With the final drive empty of oil, rolling the wheel forwards and backwards produces a very slight difference in sound. Forward just sounds like a smooth rolling bearing, backwards introduces a very slight rumble. I am only hearing it because I am actually looking for it and all this is with my ear as close as possible to the final drive, ie it is very quiet.

    A question,
    just to open up and have an investigation within the final drive, then put it back together does one need new gaskets or seals or anything?

    Work ran late tonight so I couldn't get much done, but I must say I am absolutely loving having a TIG welder.
    #71
  12. Rucksta

    Rucksta SS Blowhard

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    There is a gasket between the inner and outer housing.
    It's a good idea to have one handy esp if the drive has not been apart before.

    May as well pick up a couple of shims.
    #72
  13. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    for the FD there is an o-ring at the rear brake pivot too. The inner side cover comes off really easy. You'll need two 5mm long bolts to pop the cover.
    #73
  14. ontic

    ontic

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    Thanks fellas,

    I'll email Damien from motobins and ask if he can put together a seal and gasket 'kit' for the G/S final drive as they don't have one listed and I'm finding it hard to figure out what is suitable.

    Rucksta,
    I'll happily grab a few shims. Any suggestions as to which ones:ear I'd prefer a wild guess from you to a stab in the dark from me:lol3
    motobins list the crown wheel inner spacer shims from 1.6mm ranging to 2.6mm
    and the crown wheel outer large shim from .18mm ranging to .88mm.

    I think this order is just about ready to go through. I'm fooling myself if I think I will manage to get everything I will need in the first order anyway.
    #74
  15. Rucksta

    Rucksta SS Blowhard

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    The outer I've only seen in two sizes thick & thin 0.15 & 0.7 mm I think they were.
    Despite the listings this is all I've been able to get my hands on.

    Fortunatly there is a stack of them and they seem to pound thinner with use so I can always get close emough by swapping in new for old. 2 x 0.15 would be a good start.
    Last I bought were $8.00AUD each onshore.

    I'd leave the inner shims alone as they set the lash on the crownwheel & pinion and I'm not qualified to do that.
    You may be better with bearing blue than me but even the input seal is a challenge I don't tackle but the big seal is easy enough but you'd know if you needed it as it would visibly leak oil.

    Unless you remove the small bearing or the bush there should be no need to play in here if it was set up right and it's not broken or eliptical on the bush / small bearing as suggested.

    If the FD required more than a simple outer shimming I send mine of to Ray Peake for a complete job.


    Be aware there are at least two diffenent bearing setups on G/S FDs
    Mine is an 09/82 and has the brake cam shaft running in a brass bush at each end. Later versions have a tube running right throug the two halves. Extenaly there is little difference but the early type appears to have a 'cap' over where an axle would go through on the right hand side (if it had an axle) later models have what looks like a continuos casting instead of the cap.

    Mine has a steel stub axle and a tapered small bearing,
    Later versions have an alloy stub axle and a needle bearing. This is based on a total sample of two final dribves I've seen the inside of.

    A popular modification was cut additional grooves in the brake cam shaft to use double 'O' rings each side.
    Factory did this shortly before the change in the drives oabout the same time the rubber inserts went into the forward brake spring
    #75
  16. Sibbo

    Sibbo Been here awhile

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    The timing has to be out mate, those things are a doddle to start if things are right .The right maggy ? How about installing a coil if all else fails ...a few of the Brit bike boys do it . A better spark at low revs .

    Good Luck !


    #76
  17. ontic

    ontic

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    Great post,
    thanks.
    From the previous owner apparantly the final drive did have a slow leak- I never really saw a fresh leak as I have hardly ridden this bike, all I saw was the old remnants of a leak on the right side of the final drive.

    Yeah, thanks,
    the timing is what I have been more and more suspecting. The maggy is the correct maggy for this engine from a bunch of spare parts I bought for the engine- it is just an optional improved sprung impulse-starting maggy. Spark is bright and good, heaps better than the old one. Ie, it should be good enough and something else is the problem.
    Here's the relevant manual mention
    [​IMG]
    The problem with setting the timing (I tried last time) is where the maggy is- right up the back of the engine hard to reach well- let alone get your head in to look at close enough at the back of the maggy to tell when the points close and open- that and the 'nut' on the maggy drive shaft is actually just one of those pathetic little shallow slotted screws that are made to not work and this screw is quite seized in place. And of course the lack of timing marks on my flywheel... all fun and games.
    If I can free the the 'nut', and figure out the timing mark (hmmm, I do have spare flywheels...) then with my third and fourth hands use a torch and a mirror to tell when the points open and close I might just be able to do it!:lol3
    Big battery is going to be key though. Cranking this thing gets old quick.
    #77
  18. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    #78
  19. Sibbo

    Sibbo Been here awhile

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    Does the boat engine have a valve lifter? If it does your battery drill is a good way to get it up to speed ... then drop the lifter .A mate and i set up a similar system with a tiny little bike starter motor on a 20 hp Yanmar diesel .The pissy little starter spins it up with the lifter open then you drop it . It starts perfectly .

    Assuming it has somewhere to drive !
    #79
  20. ontic

    ontic

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    Thanks, thats a great post with some very helpful photos.

    And let me take the opportunity to post myself a note here- my shed is too chaotic for such a thing not to get lost.

    Remember- Final drive has no oil in it!!

    No to the valve lifter.
    I took the opportunity to buy a new big battery for my 4x4. The old one is still good enough but it is on the way out. Today I took this new 720CCA battery out to the boat (through the gale and the pouring rain). Sure enough, with this different maggy the timing was now out.
    I broke a couple of prized tools getting that stupid little slotted screw loose and finnaly managed to adjust the timing. I couldn't adjust it by when the points open (impossible to see when the maggy is installed- which is how it needs to be done), but rather just had to do it off the fly-wheel whose timing marks I figured out, and from when the plug would spark- and then just shift it forward and back a little to find the sweetest spot.
    With a bit of starting spray it starts and runs now. It is not perfect, and it has it's issues, but it is running and the next owner can figure it out. I'm done with that bloody engine:deal
    Tomorrow the wardrobe of sails and other extra's clogging my shed will be organised and photographed, and after one more trip out to the boat next week to take some photos and do another coat of paint it should be ready for ebay.
    Can't wait.


    Now, back to the G/S.
    I borrowed my partners fathers little old dremel to help me do the close fitting of the subframe reinforcements so that I have a better chance of Tig'ing them successfully.
    Yesterday afternoon I gave it a spin. Everything going great, just some gentle delicate sanding, until 30 minutes in the dremel makes a noise and spits a chunk of black stuff at my face out of one of the air vents and then looses power and sounds like it is only firing on one cylinder (if it had cylinders).
    Dammit, I hate borrowing tools.
    Pulled it apart and investigated- it seems a chunk fractured off one of the brushes and on its way out tore some little copper wires on the armature.
    Double dammit.
    I really am trying to avoid buying a new tool every time I have a need- but now I have to fix this one or buy another to replace it.


    I still haven't put in my motobins order.
    I need to be told off- I'm having very real and very dangerous temptations to get a siebenrock 1000cc power up kit.
    I do not need this. Tell me I do not need this, please:cry:lol3

    other than that, as I posted in the airheads piccy thread, I had a good ride last weekend. Around 1000kms of some of Victoria's best on the 90/6. Met up with the fellas from boxerworks. No I didn't stop to take any pics, just a couple when I got there.

    [​IMG]
    [​IMG]

    and this inspirational picture from the wall inside the Hotel
    [​IMG]
    #80