Leaking top trunk 1989. Found a split in the upper case.

[CaseyJ955]

I decided that while my bike is up with the forks being almost done I would try and find the leak in the trunk, and while I'm at it I might as well reassemble the trunk light correctly and put in a LED bulb. The light worked but it was all loose and rattling around in there. When I took the mirror box/light assy off the inside of the upper lid I found about an 8" split horizontally about an inch above the rear edge of the case. It actually runs between the two hinges and was enough to see daylight through the split. Somehow I feel like I'm not the first one to have this issue. There were also some stress cracks almost through just above that where the seat back hinge assembly mounts.

 

I'm guessing this happens if a large passenger throws/leans their weight against the backrest causing the plastic to stress.

 

I thought of reinforcing with a plate, rivits and sealant but I decided to take a stab at this Devcon Plastic Weld stuff I had laying around. It's a 2 part, like JBweld for plastic. I cleaned the split and surrounding areas with alcohol, also got into the stress cracks and generously slathered this plastic weld stuff into the crack. I flexed the trunk lid to open the stress cracks and worked some of the plastic weld stuff into those as well. Now that it's drying it feels pretty damn solid! I used this plastic weld to fix a water cooler once and I was impressed by how good it is.

 

I'm wondering if anyone else has successfully done these repairs in other ways? When I reassemble the backrest and mirror box I'm planning to dab a little RTV or 2B around the bolt holes for a better seal, even though the rubber gaskets are still intact, they are old as dirt.

 

I'm going to put up a pic or two after I get my phone charged.

[uhfradarwill]

I think it's a very common thing.

My bike had it but a PO did a repair with what looks to be painted fiberglass.

[saddlebum]

I used Plastex also known as PlastiFix to repair any of my cracks. I even used it to join a bottom and top half of two different side fairings to make one good one. I embed a couple of layers of drywall tape as I build it up to improve strength (I add drywall tape to JB weld sometimes for the same reason). Any way the repair was strong enough that when the bike dropped of the work table this summer, 10 years later there was absolutely no indication of failure and to this day no buddy has been able to tell were the joint is (I'm not even sure I can tell exactly anymore and I did the job).

[CaseyJ955]

I used Plastex also known as PlastiFix to repair any of my cracks. I even used it to join a bottom and top half of two different side fairings to make one good one. I embed a couple of layers of drywall tape as I build it up to improve strength (I add drywall tape to JB weld sometimes for the same reason). Any way the repair was strong enough that when the bike dropped of the work table this summer, 10 years later there was absolutely no indication of failure and to this day no buddy has been able to tell were the joint is (I'm not even sure I can tell exactly anymore and I did the job).

 

Thats a little different than what I used, but Plastex sounds pretty solid. I used up the last of mine so I'll snag some Plastex when I head to town. I like to keep plenty of stuff handy to avoid trips to town. Not sure why I didnt think about drywall tape, awesome idea. I have a couple rolls of the mesh tape, which I always preferred to the paper tape when doing drywall work. Since I rarely ride 2-up I suspect it will last awihle.

 

Thanks!

[saddlebum]

Edited February 3, 2019 by saddlebum

[slowrollwv]

My trunk is cracked around the rack mount holes but to fix it right it will destroy the spider web paint job on the bike. So I will have to live with it till I repaint the bike. I have another lid but can't get it painted to match.

[saddlebum]

My trunk is cracked around the rack mount holes but to fix it right it will destroy the spider web paint job on the bike. So I will have to live with it till I repaint the bike. I have another lid but can't get it painted to match.

Put a layer of putty or clear packing tape over the crack on the outside I use clear packing tape and rub it in real good to eliminate air pockets. Then gouge/bevel the crack out on the inside about 3/4s of the way through the plastic and so it opens about 1/4 inch wide at the surface, take care not to penetrate completely to the outside surface (I use a 1/4 inch round ball burr on a Dremel tool for this). Fill the crack with plastex/plastifix using the stitch method which is explained in the instructions that come with the kit. Once it is built up flush with the inside surface cover with a piece of fiberglass dry wall tape. Wet the area down with the liquid solution then sprinkle powder on it and then wet the powder. keep alternating until the tape is covered. At this point you can either let it cure or add additional layers of tape and plastex to build it up until you feel satisfied. Once the curing is complete peel of the tape from the outside. If the tape was sealed down well their should be no trespassing on the paint job. At best you might notice an extra fine black web line to your master piece. Note there is no heat involved here so your paint job is safe. BTW the powder is available in black, white and clear.

 

PS the sooner you tackle this the sooner you stop the cracks from spreading which they will do if left untouched.

Edited February 3, 2019 by saddlebum

[camos]

My trunk is cracked around the rack mount holes but to fix it right it will destroy the spider web paint job on the bike. So I will have to live with it till I repaint the bike. I have another lid but can't get it painted to match.

I have done two similar repairs using my favourite mix of ABS and Methyl Ethyl Ketone Solvent. One was the right front corner of the trunk around the hinge and the other was the inside corner of the right front fairing where it transitions into the removable side panel. Both had a spiderweb of cracks that went all the way through.

 

After taping the visible surface with cello tape I pushed a fairly soft mix of ABS and MEKS from the inside out to fill the cracks. Once it all set up, I left it for a couple of days, removed the tape and was left with a solid repair that did have fine black lines where the cracks were. These are noticeable from close up but not from a short distance. Both these repairs have lasted for over two years.

 

I can't say how much it cost because it was so small, probably less than a couple of dollars. No repainting required unless you are after a show bike.