Mending cracking headlight cowl?

[Asian Boss]

The headlight cowl on the old XL is cracking. It was like this when I got it but I think it's getting worse.

I haven't investigated but I suspect there's no spacer or bolt with a shoulder on so that may have caused the problems and is making it worse.

Any advice in terms of mending the plastic? Might going at it cack-handedly with a soldering iron from the inside work? I suspect most glues won't hold. I see there are various kits and products designed to do this sort of thing, has anyone any experience of those?

Cowl.JPG (325.72 KiB) Viewed 281 times

[weeksy]

Use an old fairing cast off and basically solder it, that's essentially what plastic welding is

[cheb]

I've probably got a prepatinated bolt and top hat washer if you want them.

[Asian Boss]

Use an old fairing cast off and basically solder it, that's essentially what plastic welding is

I don't think I have any old pieces of fairing. I should take the cowl off and see if it says what sort of plastic it's made from. Then try and get some, there's probably a pipe or something made from it.

[Asian Boss]

I've probably got a prepatinated bolt and top hat washer if you want them.

Thank you, that could be really useful. Those sort of things can be a nightmare to find.

[Horse]

Never done this sort of repair, but two things I've read are:
- drill a hole at the end of the crack to stop it spreading
- on the inside of the panel, cut the crack to a 'V', then fill/glue into that

Have you looked for youtube videos?

[David]

There is a tool that sets a wire accross the crack and braces the repair. I think screwdriver had one...might be worth asking his opinion any way as he is aces at mending and making....

[Count Steer]

If you have some Airfix glue, put a blob on the inside, then scratch it off. If you it dissolves a bit of plastic you can use the solvent based adhesive to at least hold it together while you work on it, or even glue a reinforcing piece on the inside. If it doesn't dissolve, glueing can be a problem - a bunch of us tried all sorts on some plastic components for a lighting installation and nothing really worked.

[cheb]

There's also a fine metal you can get, place over the crack and poke in into the plastic with a soldering iron.

[Le_Fromage_Grande]

Dirt bikes have use different plastic (that's a lot more flexible) to road bikes, I've got a feeling it's very difficult to plastic weld, but I can ask Brian the plastic welder, if you want it done professionally I can put you in touch with him.

If it was mine I'd be looking for a replacement, you can get pattern bodywork for most of the common Honda dirt bikes from yesteryear

[KungFooBob]

It's fucking fucked.

Set it on fire and claim on the insurance.

[Asian Boss]

I took the cowl off. Top hat spacers present on both sides, original I presume. No sign of identification markings on the plastic so I have a bash at it with an old soldering iron. It seems to have done the trick! Maybe it will break again as soon as I start it up.

[derek badger]

Its an ugly fix, but I've had good success with this method...

Get a 1mm drill bit and stainless steel lock wire. Stitch it up like you would do a wound then cover it in epoxy resin.

[Asian Boss]

I think it's cracked again.

I need to to look reasonable as it's highly visible.

I might buy some plastic welding rods and have a go with those.

Does anyone know how to tell what sort of plastic it is?

[Count Steer]

I think it's cracked again.

I need to to look reasonable as it's highly visible.

I might buy some plastic welding rods and have a go with those.

Does anyone know how to tell what sort of plastic it is?

You could try a flame test. It's not exactly definitive but worth a try?

https://www.twi-global.com/technical-kn ... a-plastic

PS The commonest plastic for them is ABS.

[Le_Fromage_Grande]

I think it's cracked again.

I need to to look reasonable as it's highly visible.

I might buy some plastic welding rods and have a go with those.

Does anyone know how to tell what sort of plastic it is?

It's dirt bike plastic, it won't plastic weld, it shrinks when it melts, just buy another and stop being a tight wadge

[Asian Boss]

I think it's cracked again.

I need to to look reasonable as it's highly visible.

I might buy some plastic welding rods and have a go with those.

Does anyone know how to tell what sort of plastic it is?

It's dirt bike plastic, it won't plastic weld, it shrinks when it melts, just buy another and stop being a tight wadge

If I could find one I would but it's a very rare bike.

[Le_Fromage_Grande]

Stick a picture of it up showing the whole shroud, it's bound to be the same as another Honda, I might be able to suggest some to try.

[Screwdriver]

Hot staple is what you need for that. You can also plastic weld polypropylene (if that's what it is) but you'll need a hot air welding gun. Soldering iron is too hot and will burn the plastic (it will also burn ABS).

Plenty of people out there will tell you they can shove a soldering iron into plastic and "look I fixed it". Fact is, they have made a brittle repair which will crack and split as soon as you try and flex it.

[Asian Boss]

Hot staple is what you need for that. You can also plastic weld polypropylene (if that's what it is) but you'll need a hot air welding gun. Soldering iron is too hot and will burn the plastic (it will also burn ABS).

Plenty of people out there will tell you they can shove a soldering iron into plastic and "look I fixed it". Fact is, they have made a brittle repair which will crack and split as soon as you try and flex it.

That sounds like the repair I did!

I've Googled hot staplers, they sound like they will do the job.