Holes No More – Part 2

A few photos of the finished repair job. After trimming the corner I rebuilt with a knife and removing nubs sticking through the holes to the inside with a sharp putty knife, I used my little right-angle sander with a 25 grit disc to remove the excess and smooth things out.

Smoothed repair

Smoothed repair

Rebuilt corner smoothed out

Rebuilt corner smoothed out

Smoothed repair

Smoothed repair

Inside left

Inside left

Inside right

The new plastic has a lower melting point than the original plastic, so during sanding it would melt slightly if I stayed in one place to long. So I’d work until it started getting tacky, then move to another area while that cooled and so on. Eventually I got it all shaped to my satisfaction. The screened over area still protruded a bit more than I liked – if I had it to do over again, I’d attach the screen to the inside and then fill the hole from the outside. A bit tricky to do it that way, but it would have turned out better.

I cleaned the area to be covered with heat barrier with Acetone and then cut out a section and covered it.

Tracing around the airbox

Tracing around the airbox

Laid out on the back of the heat barrier

Laid out on the back of the heat barrier

Checking fit

Checking fit

Heat barrier applied

Heat barrier applied

You can see it’s nice and flat except for one budge where the screen was applied. No biggie – it’ll be be hidden by the exhaust. I remounted the airbox once again to test the fit. So much nicer not to have all of those holes everywhere!

Right side

Right side

Top view

Top view

Rear view

Rear view

Now I can finally move on to the next item on the checklist…

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Holes no more

The plastic welding kit I ordered arrived early this week and I made a little time this evening to give it a try. In short, it works exactly as advertised. Once the iron is up to operating temperature, it melts and flows the rod with ease. At first I tried holding the iron on the inside of the airbox and feeding the rod in through the hole to be filled. That wasn’t working too good, so I tried applying regular old clear packaging tape over the holes on the inside and then melting the rod into the hole from the outside. That worked great – I just melted the rod over the hole and then smoothed it out.

Rebuilt this entire corner

Rebuilt this entire corner

Top

Top

Melted area completely closed.

Melted area completely closed.

Back side

Back side

Shock side holes gone

Shock side holes gone

For the large melted hole I first applied rod around the hole, cut out a piece of the stainless mesh the right size, melted it into the previously applied rod and then covered it with more rod. The resulting surface isn’t smooth or textured like the original plastic, but it seems to be just as strong and flexible. If I wanted to, I could sand it to look better. A little trimming and the airbox will be ready to install.

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Airbox agonizing

Despite my best efforts to find another, there just doesn’t seem to be an airbox/battery box any better than the one I already have. Mine has perhaps two dozen non-original holes drilled into it. I really don’t understand what the objective was of the person who drilled them. The whole top of the airbox is open, an area approx. 4″ x 7″ – if that doesn’t flow enough air, adding a bunch of holes isn’t likely to help. Anyway, most if not all of them need to be closed up and there’s a large melted area from the exhaust being too close as well.

Test fitting the airbox

Test fitting the airbox

Needed a little trimming at the front to clear the Dellorto carb.

 

Couple of holes on the back to close up too.

Couple of holes on the back to close up too.

It’s going to be quite a bit work to fix all of that. I explored the possibilities of a) making another out of fiberglass or b) making another out of aluminum. Either would take a considerable amount of time – maybe more than fixing the original.

I finally decided to buy a reasonably priced plastic repair kit from Urethane Supply. It’s basically a large soldering iron with a flat tip and some “welding” rods made of a plastic compatible with numerous types of plastic. It also comes with a stainless steel mesh “patch”. 

http://www.urethanesupply.com/Airless-Welders-1/Micro-Weld-80/

Hopefully it’ll work well enough for me to fill the holes at least and maybe rebuild the melted area. If I can’t fill in the melted area, I’ll simply cover it with the “heat tile” material I got from Maier Plastics. It’s an aluminized outer covering over a fiberglass insulating material and an adhesive backing. Sticks very well to the polyethylene plastic the airbox is made out of.

Maier heat tile

Maier heat tile

Testing a small patch of heat shield material

The heat shield material goes on the airbox and side panels to keep them from being melted anyway.