plastic weld how to

[derf]

I wrote this a few years back, and while searching for it in another post and not finding it on twf I am gonna copy paste the whole thread here:

Ok I'll let the pictures do the talking. I bought the bike with some minor damage to the fairings, and I know how to repair plastic so....

I used a 50 gal air compressor, hooked to the cheapo harbor freight plastic welder, a bic lighter and a steel ruler are used for shaping the plasitc if it gets too hot and starts to deform. I also use a heat gun to soften the plastics if I need to move/form/fix any out of place pieces.









Now the upper fairing has all the cracks fixed and they wont get any worse, on to the mid fairing





Mid fairing is fixed. Next on the list is sanding of the current welds, shaping of the filler piece to go in the hole in the upper fairing, trimming of the upper fairing to fit the new filler plastic, welding that in, a very little bit of body filler, and sanding that down so it matches the curves of the fairing. I'm not going to paint it, I just cant justify spending the money on pro paint. I will however be using vynil to match, yellow over the mid fairing only over the part where the crack is, and white over the corner of the upper fairing, both sides to match, and probably going to throw on a fireblade sticker over the yellow to whit transition to make it look like the white belongs.

[derf]

I cut the fairing so the edges of the hole were straight, makes it easy to fit a filler part in there




I heated this square until it was flexiblethen clamped it to the fairing and waited for it to cool. Once it was cool I heated up the right edge to form the 2nd curve and the corner. Once that was done I marked from the inside of the fairing where to cut




This is the final filler piece ready to get melted in. I cut it too big by a fe MM on each edge and hand sanded/filed it to fit. it has to fit very tight or the joints will fatigue and crack over time.




First pass with teh plastic welder, came out good, but it looks like shite




Ok, that looks better, was sanded using my home made 1x3" block sander







There are still some divets and low points where the heat distorted the plastic, which requires some bondo. I try to get the plastic as flush first before going to bondo. I also do my best to use as little bondo as I possibly can.




And finally the finished repair, sanded from 60 to 1000 grit paper, the surface feels like an egg shell, and is ready for paint, or in my case vynil







Total 'actual' work time is just under 5 hours. I probably put another 5 or 6 into it waiting for the plastic to cool so I could keep going without melting the plastic until it droops or distorts beyond repair.

[derf]

The finished product. I'm pretty happy about it, there are some minor imperfections, but you really have to look carefully to see them. I was contemplating adding another yellow piece of vynil to the corners just to keep the black from dominating the front. this would turn the black into more of a stripe. I also added the CBR sticker over the headlight, I was trying to make it look like the black corners were a factory design, I should have done the outline of the R in yellow instead of white, but its too late now.

Also take not of the left side mid panel where I fixed it.

[Dave]

you should come fix my upper lol

[derf]

Originally Posted by Dave

you should come fix my upper lol

You should bring your upper down here for me to fix

[Mikey]

What kind of prep work do you do before the plastic welding? I've heard that you're supposed to notch the back side into something like a V shape; is that right?

I've got a crack in a fairing that's been there for years and is finally starting to spread a bit, so I'd like to stop it from getting any worse.

[derf]

Just sanded into the crack a little, not much really. I had tried putting a V indent front and back but that made the plastic too thin and it would actually distort way to easily.

[Trip]

nicely done, was this from the towing incident?

[derf]

No, thats how I bought the bike. I got it from a dealer for $2500 with the body damage, plus a minor oil leak from the valve cover gasket.

I stopped by the local dealership to buy a new pair of gloves and to look at bikes, was talking to some dude who just traded in his old 900 for a new gsxr750, and the guy told me the whole history of the bike from when he bought it new in 99 until he traded it in, for a little over 2k. He was genuinely sad to see it go. At the time I would have almost definately never bought a 900 being the wheelie king of the 90s and being the original stunta bike. But I went inside, and saw the dealer wheeling it in back, it was in pretty good condition, so I offered them $2500 for it out the door including tax title and tags, which they did on the spot. They did try and talk me into letting them fix the head gasket which they said was leaking oil, new tires, and the body work. I took it as is

I figure it would have cost them another $1k to get it to showroom condition and charged me $2k. Either way it was a good deal for me. I did the bodywork, tires, and changed the valve cover gasket for $350, and have put one or two miles on it since.

Originally Posted by Trip

nicely done, was this from the towing incident?

Surprisingly enough the majority of the damage from the tow incident was to the other side

[derf]

this was my first try at plastic welding the year before:

so last season my lower fairing decided it didn't like staying in 1 piece and found itself a brick to crack itself with, pics in this thread:

http://www.ex-500.com/index.php/topic,2082.0.html

Anyway i went out this week and grabbed a plastic welder to try and fix it, well fix it i did...

I went out and bought the plastic welder today, and tried it out for the first time.

Wow it is easy. I think knowing how to tig helped out alot as it is very similar.

I was able to fix a rather large crack across the lower part of my bodywork that basically split it in 2 except for a two inch section. I also fixed some stress cracks around a mount point, which probably came from the same brick that broke the rest of it.

Anyway got the welder homehooked it up to the compressor, plugged it in and and went to town. First i grinded down the crack and took off some paint about 1/2" away from the crack, and heated it up with the welder, then I heated up the rod and mixed the 2 together.

After I was done adding filler plastic I took my sand paper and rubber the filler down to the same level as original plastic. I noticed that the filler rod definatly joined the 2 pieces together good, but I did melt away a little too much plastic in some places, not bad, I will just fix the rest with body filler.