Another Neos Build....but not like Bunnymum's.....

Discussion in 'Scooter Projects' started by Stevep, Dec 15, 2018.

  1. Stevep

    Stevep Well-Known Member

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    4,861
    So most of you know I like to have a play with my toys every now and then, strip them, change everything, re-build and paint them, flog them.
    A few months ago I picked up a couple of Yamaha Neos for practically pennies. I sold one straight off the trailer for the same amount I paid for both, so this one owes me nothing to start with. A good start me thinks.
    You might have seen this one hiding in the background of some photos I may have posted in other threads.

    IMG_20180602_143632[1].jpg

    Body work is in decent shape, lower belly pan needs some plastic welding but every other panel is good.
    Engine is seized as expected, carb is missing, headlight bulb holder missing, stand missing, the usual stuff really.
    Finally got it onto one of the ramps to start stripping it. Bodywork off, attack the engine and get that piston out. Plenty of ageing spider webs under there.

    IMG_20181213_142724[1].jpg
    Piston out, can see straight away why it failed, the gudgeon pin circlip had come out, mullered the bore and piston

    IMG_20181214_164731[1].jpg
    IMG_20181214_164740[1].jpg
    Crank and bearings are good, no sideways play in the rod or signs of seal leaks, but crank bearings and seals will get changed anyway as a matter of course.
    Stripping out the rest of the bike revealed that, unusually, it was totally standard. No changed reed block, standard clutch and bell, standard variator still with the restrictor ring in place. So maybe this hasn't been thrashed to within an inch of it's life then........

    IMG_20181214_164713[1].jpg
    All the electrical connections need a good cleaning, especially the earth points, starter motor points, coil connections etc, as expected.
    Engine out and on the workbench. Here comes the good bit.

    IMG_20181214_164937[1].jpg
    You see that tube that mounts the front of the engine? That has to come out before you can split the engine cases. It has 2 circlips, each end, on the inside, and that tube passes through a bearing at each end. They will be all rusted up and there is no point at all in trying to do anything else with them except get brutal. Grab the hacksaw or angle grinder with a cutting blade on it and cut through the middle of tube.
    IMG_20181214_165501[1].jpg

    Leave each half in place, then split the engine cases, it's easier to get that tube out once the cases are split.
    Once the cases are split you can quite easily remove the circlips and knock the tube and bearings out of each half. When it comes time to rebuild the engine you have a choice of replacing the tube with a new one or welding the two halves together again, but you will need new bearings in there because the others will be knackered.
    Engine all split and ready for cleaning (and painting)
    You can see the tube on the bench in two halves.
    Have a feel of the gearbox shafts and bearings while it's on the bench for sideways/up and down movement, any play, change the bearings and seals. This box feels a bit rough so it will get opened up and inspected later today.

    IMG_20181214_175346[1].jpg

    I decided NOT to go stupid on this one for a change. It will stay standard, cylinder wise, but will obviously have the full de-restriction, 17.5mm carb, open filter, carbon reeds, un-restricted manifold etc etc.
    I know they go well just doing this, no need really for the full upgrade to be done.
    One thing I did notice was that this bike has the manual choke lever on the left hand handlebar, as standard, good from my point of view.
    I'll post more as it moves on.......
     
  2. scubabiker

    scubabiker NITROJUNKIE

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    Am I right in thinking the later engines had that tube split in 2?
    I cant recall ever taking a circlip out a jog engine.
     
  3. Stevep

    Stevep Well-Known Member

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    No idea to be honest
     
  4. MARSH

    MARSH Whooooo!

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    Rides:
    Piaggio Typhoon
    A bit of emery paper will have that piston looking like new !;)
     
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  5. Stevep

    Stevep Well-Known Member

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    4,861
    I'm thinking of buying a new machine for the garage so I can do my own re-bore's on the scooter barrels.
    I've probably got a dozen knackered barrels on the shelves that I could take down to my bloke and have them re-bored from 40mm to 47mm, or 50cc to 70cc if you like, but it would be ideal if I could do them here at will rather than take them all down and have them sitting around until I need one.
    Working to the tolerances required is not a problem with my background.
     
  6. scubabiker

    scubabiker NITROJUNKIE

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    The one we had at the shop was scary as fuck, im not easily frightened, but that bore machine was something else.
    It was ancient though... im pretty sure it was built by vikings and ran on the blood of sacrificed virgins (scooter owners ha!)
    I guess modern ones are more like a lathe or milling machine, with a clamp to hold the cylinder?
     
  7. Stevep

    Stevep Well-Known Member

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    4,861
    Very similar yes.
    Small bore re-bore machines are hard to come across so I'm thinking of the lathe or miller route.
    I'm sure I could make an adapter plate to mount the cylinder onto, dial gauge to clock the run out, auto-feed the speed to fetch out the excess then hone the final 2 or 4 thou.
     
  8. Stevep

    Stevep Well-Known Member

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    4,861
    Just to clarify, I could mount the cylinder using it's own stud holes, not using clamps.
     
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  9. Stevep

    Stevep Well-Known Member

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    Input shaft bearing was a little noisy so that's been changed. Cleaned up the cases, topped up a few imperfections with chemical metal, all ready for blasting off with thinners then priming and painting tomorrow.

    IMG_20181216_141844.jpg

    IMG_20181216_191834.jpg
     
  10. Stevep

    Stevep Well-Known Member

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    4,861
    Nice Matt black on the engine cases, it's still wet in the photo but will dull down, honest.

    IMG_20181217_161246.jpg
     
  11. Stevep

    Stevep Well-Known Member

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    4,861
    Engine done now, ready to go back in.

    IMG_20181221_152801.jpg
     
  12. Stevep

    Stevep Well-Known Member

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    4,861
    Been a bit lazy with the pictures on this one, but the engine is back in and running now, new crank bearings and seals, new cylinder kit, new gear oil, wheels painted, new tyres, new brakes, new 17.5mm carb with open filter, jetted to suit, new fan cover and shroud.
    Decided to give it a respray as well to bring it up a bit.
    Got to replace the front master cylinder, waiting on that to arrive but I have got one I can use for now, also need to replace the starter and horn switches, again waiting for them to arrive.
    I'll stick a couple of pics up later this week, then it's off to the MOT station and then up for sale.
     
  13. Stevep

    Stevep Well-Known Member

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    4,861
    Got the switches from a fleabay seller last week, tracking number included, hadn't received them so emailed Hermes.
    They deemed it "lost".
    Contacted seller, they sent another one yesterday, just got an email from hermes, will be delivered today.
    Redeemed themselves they have:)
     
  14. Stevep

    Stevep Well-Known Member

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    4,861
    Parcel just delivered:D, playtime again
     
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  15. scubabiker

    scubabiker NITROJUNKIE

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    Nice.
    Don't suppose you have a piaggio cdi kicking around do you?
     
  16. Stevep

    Stevep Well-Known Member

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    4,861
    If it's the red ones, yes, I've got a couple lying around in the boxes, no idea if they work still but you're welcome to them.
     
  17. scubabiker

    scubabiker NITROJUNKIE

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    Are they the 2t ignition curve? I know there is a 4 stroke cdi box too.
     
  18. Stevep

    Stevep Well-Known Member

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    Pretty sure they were the 2T ones, I seem to remember at least one came off a runner 50 some time ago
     
  19. scubabiker

    scubabiker NITROJUNKIE

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    I will take one mate. I will send you a PM
     
  20. Stevep

    Stevep Well-Known Member

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    4,861
    Proper lacking in pics on this one, however, finished.
    Nothing special, just de-restricted with a 17.5mm carb and open filter

    IMG_20190112_123155[1].jpg IMG_20190112_123309[1].jpg IMG_20190112_123627[1].jpg
     

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