Topic: How would you repair cracks on sidecovers?

[Zane]

Wow!  That fiberglass method side cover repair looks really great J. B.

I’m sure most (if not all) of the other methods work pretty well too.

I’m not certain about the quality of those 750 side covers, compared to the ones from my 400F.  (I suspect the smaller, 400F side covers may be marginally softer plastic, but I’m not certain.)  Regardless, I’ve had very good results with this stuff;

http://www.tapplastics.com/shop/product.php?pid=108

It's called "MarineFIX" and I think it's made by the same people who make all those "goop" products.  I like the marine fix stuff because it seems to cure to about the same density as the plastic parts on my motorbike.  (At least on the two parts where I seem to need it most - the side covers and the headlight bucket.)  It's cheaper (by volume) than JB Weld.

When I first used it the results weren’t super, though.  That was because I used it like a filler, and just cleaned up the "wound" with sandpaper, and used it like poly filla.  It was okay, but not as good as I thought it should be.  So I started fixing cracks by actually cutting the wounds bigger a bit.  So a normal crack, in which the plastic still butted up together - I cut out about half a mm or so along the length of it, and then filled in the hole with the epoxy.  It works really well, and I think those areas where I did that are now stronger than they were before the damage. 

I also like it because, like I said, it's roughly the same as the plastic - maybe a little more dense, but not much.  It's almost the same colour too, which helps (albeit minimally) with the painting process.  It dries very quickly, which is nice, and it's reasonably priced.

However, having said this, when I look at the before and after shots of paxtonpony’s sidecover, I sure wouldn’t tackle such an extensive repair (rebuild) with this Marinefix stuff.  I’d probably go the same route - a fiberglass backing.  After doing that I’d probably use the Marinefix like Polyfilla and fill from the front for the finishing surface.

How ever you tackle your repair, good luck to you......

Cheers

[rhinoracer]

Hot air welding is the most permanent method, i you're skilled enough you can even blend in the welds for an unnoticeable repair.

After that, MEK is the closest to plastic welding.

[cb350twin]

All I know is that JB Weld dose NOT work, works great on other things though.

[Raul CB750K1]

When I bought my CB750, I tried to remove the left sidecover and it cracked. I thought to myself "DAMN!" but then I discovered that the crack had been repaired with super-glue by the previous owner, I just happened to break it by the same crack.

Super-glue is really hard if the contact surface is wide enough, but not very useful when the contact surface is thin and the breaking force is applied parallel to the surface. I knew it was necessary to reinforce the sidecover in order to absorbe the tension so the sidecover won't crack again. What I did was to apply sticky fiberglass mesh, crossing it, and then apply fiberglass bondo over it. That fiberglass mesh is used to repair wall cracks on brick walls. The plaster is removed, the mesh is applied over the crack, and then new plaster is applied. The mesh will keep the crack from expand and contract. I replaced the rubber grommets too, and instead of pulling the sidecover I always use a flat screwdriver to pry it open one tang at a time. I don't remove the sidecovers often, but have had no problems until now.


Raul

[nteek754]

Hey all  I use to build fiberglass boats and gained some knowledge on  fiberglassing since then I have  repaired. reenforouced a bunch of these covers  makes them  a bit heavier than stock but a whole lot stronger  I use the  glass cloth and of coarse resin but be carefull too much hardner and you can worp the plastic cover (my rookie daze) but it works fantastic  25.00 bucks + shipping and handleing  have fun seven fifty four ever Craig in Maine

[Terry in Australia]

Hey all  I use to build fiberglass boats and gained some knowledge on  fiberglassing since then I have  repaired. reenforouced a bunch of these covers  makes them  a bit heavier than stock but a whole lot stronger  I use the  glass cloth and of coarse resin but be carefull too much hardner and you can worp the plastic cover (my rookie daze) but it works fantastic  25.00 bucks + shipping and handleing  have fun seven fifty four ever Craig in Maine

Have you thought about casting your own fiberglass sidecovers mate? I'll buy a couple of sets if you do, no worries! Cheers, Terry.

[BobbyR]

I would buy a set