Plastic repair/welding

  1. I have acquired a second quad (Kawasaki klf 300)for penults nothing doggy just a client that had one of his idiot sons prang it has more money than sense so just went out and bought a new one.

    All damage is cosmetic slightly bent carrier and mounts which has all come back cracked light mount and cracked front plastic (fender)…..

    The steel work is a breeze done in less than an hour, however repairing plastics is a different world to me, the crack is around 3" long and although I could just leave it I thought Id tidy it up whilst its striped encase I ever wanted to sell the bike...

    I could buy S/H plastics however they wont colour match have the correct decals and make the bike look sus if and when it does go down the road.

    I'm wondering how I could make the best decent repair, looking at some of the cheep welders on ebay or the epoxy type repairs, I was wondering what the collectives views are on repairing it to a decent (not perfect) repair?
  2. Dcal

    Dcal Forum Supporter

    Antrim Northern Ireland
    Plastic welding would be the way to go if you have, or can get a lend of, a welder and it is weldable.
    Getting a match on the rods for the type of plastic can also be surprisingly difficult, but a good work around is to cut thin strips off an inconspicuous bit of the part being welded and use that for filler.
    Hopefuldave and snowcat like this.
  3. What sort of money is it for a welder????? with the amount of plastics on kit these days I'm sure its something that would get a bit of use.

    Also how do you know the plastic type all seams a bit of a minefield.
  4. MCKDAVID Member

    you can get "reasonable" success fusing the cracks with soldering irons and bits of the same plastic. you can use bits of tie wraps etc usually you'll see markings on the plastic which define which type / grade it is. you can also melt in steel pins etc etc to reinforce it.

    have a search on youtube there's plenty of bike type repair videos which cover it. motocross type bikes are favourite for regular plastics damage.
    Seano and Parm like this.
  5. monkeh

    monkeh Member

    Corby UK
    Heat gun is better than a soldering iron as you want to just heat the plastic enough to melt it, not burn it.
    DAPPH, slim_boy_fat and 8ob like this.
  6. MCKDAVID Member

    agreed you don't want to overheat it, that's why I prefered the soldering iron, very localised heat, the hot air gun had the whole area softened before the bits melted.
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  7. MCKDAVID Member

    one thing you have to be careful with the fumes, heating any of the plastics irrespective of which method can cause fumes, always be in well ventilated areas and check which plastic... don't want to get toxic fumes around you...
    DAPPH, Parm and eLuSiVeMiTe like this.
  8. eLuSiVeMiTe

    eLuSiVeMiTe Member

    Bedfordshire England
  9. Farside

    Farside Badly Welded Man

    pipes layout 02.jpg My recent foray into plastic welding.
    Turned out all right, apart from the lurid colour match. The can is clearly identified as HDPE, and so is the bleach bottle that donated strips of itself to the cause.
    My first try, using a 25W iron, was hopeless.
    Second go, using a 100W iron controlled via a light dimmer was the final solution. I reckon it was around 50 or 60W to get a nice melt and prod and smooth-over action.
  10. addjunkie

    addjunkie Member

    Northumberland. Reet oot in the sticks
    Ive do e it with a soldering iron, but have also had success with a hit of ali on the back, a few holes drilled and epoxy adhesive, then smooth off
  11. Turbo Member

    Fermanagh, Northern Ireland
    I have one of the leister welder Chinese clones. I've used it to repair some plastics but in hidden areas as I struggle to get a pretty weld. It bears no resemblance to welding metal & no matter how many videos I watch I can't get the hang of it.

    You basically heat the part & the rod at the same time until they're soft enough & then push the rod into the part so they bond together. It's a very fine line from being too hard to stick, correct softness & melting into a blob!

    You also need the correct filler in the right colour, otherwise your repair will look awful! No matter how good your welding is you will not get an invisible repair without filler & paint!

    I would spend the welder money on some s/h plastics & a new set of decals.
  12. pedrobedro

    pedrobedro Man at Matalan

    CX Derbyshire
    Chap who did the bodywork on a bike round at the shop was looking round a fairing with a split and said it was going to be a cheap repair as he could use a milk carton as filler, it worked spot on. I've seen Lego bricks dissolved in acetone to repair broken ABS panels as well.
    DAPPH, Hopefuldave and Parm like this.
  13. I bought a Makita hot air gun with an attachment for feeding in plastic "welding rods" and never really managed a decent result . Q-Bond is now my adhesive of choice.
    Johnrob likes this.
  14. slim_boy_fat

    slim_boy_fat Forum Supporter

    @snowcat Drill a small hole at the end of the crack until you decide the way ahead - it'll stop the crack going any further.
    Wany, MCKDAVID, Parm and 1 other person like this.
  15. angellonewolf

    angellonewolf Member

    bristol england
    as above drill end add pins along the crack the best ive found is larger staples melted in from the back and fiber glass the back to make it stronger

    you will still the crack but it will be a lot less noticeable if pined and glassed from the back and should be easy sellable as that (me and son done meny over the last few years as hes been playing with mini motos most came with cracks in at least 2 of the plastics over the bike

    we got quite good at putting pins in adding plastic fiber glassing and sanding then paint with poundland primer and matt black hides meny a problens unless you look close if you wanty to go that far but takes more time than it worth

    as said pin from back and fiber glass should do you
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  16. eLuSiVeMiTe

    eLuSiVeMiTe Member

    Bedfordshire England
    I gave up on my trials bike rear mudguard/seat all in one.
    Bent and riveted a plate and cable tied the mudguard end in.
    Everytime I launched the bike is have to repair it again. Easy to replace the ties.
    Couldn't tell it had been welded after the first repair.
    Unfortunately new parts were unobtainable.
    Parm likes this.
  17. angellonewolf

    angellonewolf Member

    bristol england
    ^^^^ i hope hes not going to launch a quad might hert a bit
    Parm and eLuSiVeMiTe like this.
  18. ukracer Forum Supporter

    Very interesting. I learnt today that is how they make ABS stick to a 3D printers bed.
    10 to 1 mix with Abs filament and make a slurry/juice.
  19. Yamhon Member

    Not sure if this as been mentioned yet, but Andrew Camaratta on YouTube has a few videos of him repairing jet skis and boats on his channel; those might be helpful.
  20. Hopefuldave Intergalactic pot-mender

    The Shed of Danger, surrey, England
    My preferred method, I get ABS filler panels delivered with datacentre racks...
    Put the magical grey goo on in multiple thin layers though, or it can swell up while hardening (I think the acetone gets trapped by the hardened skin and "bloats" the inner layers)

    Dave H. (the other one)