What flexible filler to use on motorcycle fairing panels?

[ajlelectronics]

But plastic primer is there to promote adhesion between the plastic and other paints, the epoxy on top gives you a base to fill on with less chance of going back through the plastic primer

Nope. The epoxy primer is there to give the maximum possible adhesion to the panel and to seal it. Epoxy primer replaces all the traditional adhesion promoters as it is superior to any of them, galv, plastic, aluminium etc, they are all far better in epoxies.

The job is only as good as the weakest link, so if you use plastic primer, that becomes the weakest link.

 

[the snooper]

Nope. The epoxy primer is there to give the maximum possible adhesion to the panel and to seal it. Epoxy primer replaces all the traditional adhesion promoters as it is superior to any of them, galv, plastic, aluminium etc, they are all far better in epoxies.

The job is only as good as the weakest link, so if you use plastic primer, that becomes the weakest link.

Well untill I read different I'll use plastic primer, we all know some plastics don't glue, even with epoxy !

 

[the snooper]

Nope. The epoxy primer is there to give the maximum possible adhesion to the panel and to seal it. Epoxy primer replaces all the traditional adhesion promoters as it is superior to any of them, galv, plastic, aluminium etc, they are all far better in epoxies.

The job is only as good as the weakest link, so if you use plastic primer, that becomes the weakest link.

Do You Need To Use An Adhesion Promoter For An Epoxy Primer On Plastic?​

As we have touched on above twice, we would always recommend that you use an adhesion promoter on your plastics prior to applying your epoxy primer if possible. This tends to offer you the absolute best possible performance and almost guarantees that the primer will work well unless the plastic in question is ABS plastics.

 

[mangocrazy]

Looking at the Technical Data Sheet for Upol Plast X 6, it indicates that no primer (be it epoxy or plastic) is necessary. So they are obviously confident in its ability to stick to the substrate. They do specify a max fill depth of 2mm, however. Parts of the fairing may need a bit more than that, I think. Would that be 2mm per application or 2mm in total?

 

[CompoSimmonite]

Thanks for all the suggestions/tips. Rather than replying individually I'll try and cover it all in one post.

1. Replacement panels are simply no longer available. A good copy would have been my preference, but they are also non-existent. It's for that reason that I refuse to cut up my OE panel and looked for one that I could cut about without feeling too guilty. I need to modify the top fairing to accommodate higher bars which in turn are needed for my ageing bones.

2. The section that has the hole is problematic, as immediately behind that (and in very close contact) is a snorkel leading to the airbox. If I add extra material inside the fairing that will push it out of line and put all the fairing and screen mounting holes out of position on that side. So I need to find a way of sealing that hole without encroaching into the internal space.

3. Before posting I did a search on Ebay looking for flexible plastic filler and there appear to be a number of options. Most of them claim they are formulated for bike fairings and car bumpers, but I always prefer a personal recommendation rather than just manufacturer's claims. One that did get my attention was Upol Plast X 6 'highly flexible body filler for plastics'. Upol are a major player in the paint/filler game so I'd hope it would do what it says on the tin.

https://www.u-pol.com/uk/en-uk/prod...st-x-highly-flexible-body-filler-for-plastics

Have you thought of using your original, mint, panels as a pattern to make a mould so a copy could be made in fibreglass ?

 

[mangocrazy]

Have you thought of using your original, mint, panels as a pattern to make a mould so a copy could be made in fibreglass ?

I like the idea, but it would be well outside my ability to do it.