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Discussion Starter #1 (Edited)
Part 3 of the AdvWing build. Follow these links for Part 1 and Part 2.



Recently, I've turned my attention to bodywork. I had intended to mate the rear fender of the CR125 with that of the GL. I have a couple GL fenders, so I can experiment a little. I took the rattier of the two, and cut away the fender just below the "lobes" forward of the tail light. Holding the CR fender to this, I realized that I'd need to discard 2/3rds of it. Then I noticed that the profile was not too different from the part I had just removed.

So, I cut away the middle of the stock fender, where the license plate bracket was, and started shaping the cut edges to match up, with the shortened fender tail at a much shallower angle, like on a dirt bike. I originally planned to use Plasti-Fix to attach and fill the seam. (I had bought a kit a couple years ago to re-stud my side cover badges, and have used it to good effect on various other projects around the house.) I finished shaping the parts to my liking, aligned the pieces, and worked a good bead into the entire seam. Then I noticed it was crooked! :( In pulling it apart the next morning, I found that the bond had not been as strong as I had expected. At the time, I attributed it to not having chamfered the edges, hence poor penetration. But in retrospect, I'm not sure that this is the right solution for this material.

While I reworked the fender tail, I found a tutorial on a sport bike forum about plastic welding bodywork, and using ABS cement (rather than Bondo) as a filler. Since this appeared to be ABS, I gave it a try.

I wrapped the tip of my soldering gun with aluminum foil to prevent contaminating it for future use.


Then I taped the two pieces of the modified fender in place, tacked a few spots, and then worked slowly over both sides of the entire seam, being sure to penetrate fully, and using strips of scrap (after stripping the paint) as feed stock. The resulting seam is solid, but ugly. It will need some finishing.




The new skill was immediately transferable. This is the broken chain guide on my daughter's bicycle. :)



Here are a few comparison shots with the stock GL fender.




Here it is mounted.


And with the wheel.


Next step: filling and sanding.


R
 

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Discussion Starter #3 (Edited)
If it were just a little steeper, this line would be perfect.



If this one ends up being practice, I'll be attentive to that when I modify the other fender.


R
 

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Discussion Starter #4 (Edited)
According to the tutorial on the Ninja forum, the ABS cement is a little thin to use as a body filler. The recommendation is to leave the can open to evaporate away some of the solvent. If it becomes too stiff, it can be thinned again using acetone or MEK. Another option is to dissolve clean scrap pieces into the cement. Or just dissolve the scrap into acetone or MEK. Then the resulting plastic will be a 100% match.

Cool! I have lots of scrap.

So, I minced up the piece I had been using as feed stock, and put it in a glass jar with a bit of acetone. By the next morning, it had done ABSOLUTELY NOTHING! On a long shot, I next tried acrylic cement (the water-thin stuff, don't remember the brand) and PVC pipe primer (mostly MEK.) Nothing.

I'm pretty certain now that our rear fenders (and maybe the other plastic parts) and High-Density PolyEthylene (HPDE.) It's an insoluble thermoplastic, the same stuff in milk jugs and garbage carts (The blue one in my photos is a new Minneapolis recycling cart. It makes a great work table. :D) I don't think I'll find any way to properly fill it, other than by heating feed stock.


R
 

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Discussion Starter #5 (Edited)
New direction. I decided to make some custom ends for my soldering iron (not the gun.) I finished the flat blade yesterday. I'll post pics after I finish the curved blade. They should effectively serve as heated trowels to smooth over the seam. Then I can sand out the blemishes.


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Hi Randall....I have some CX500 rear fenders that i could play with, one that's cut up....and i have a plastic welder made by the good folks that make Plasti-Fix. I bought the welder to fix stress cracks in a kayak I used to own....it went through a tornado and when it fell out of the sky it landed on a metal t-post.....(I conveniently wasn't in it at the time).

I also have some plastic rods for filling holes and cracks....I'll give it a try on the cut up CX fender and if it works it just may solve your filling problem. Kayaks are HDPE also, I believe..... You may be able to "weld" the plastic if you have a HDPE fill stick (part of the kit from Urethane Supply) and a heat gun. The stress crack in my kayak was easily healed simply by heating it with my HFT $9.95 heat gun......when the plastic turns shiny its melted and can be formed any way you want....might want to have some nice smooth non-rubber gloves on....other wise you leave fingerprints in the plastic not to mention the burned fingers......

I'll let you know what happens.

Sorry I missed you yesterday....

Did your wife tell you that after I gave her the CDI and highway bars I asked her where I should put the motorcycle I brought you to her great surprise (and consternation)?

It wasn't my idea....Dan put me up to it.....:D..........

Victor
 

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Discussion Starter #8 (Edited)
I did use my heat gun to soften and bend the forward tips of the tail piece to lay down on the "lobes." I hadn't thought about using it for filling.

If the custom tips in the soldering iron don't work out, I'll give that a try.


R

P.S. Heidi mentioned your joke. She wasn't amused (because it was plausible.)
 

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Hi Randall....I have some CX500 rear fenders that i could play with, one that's cut up....and i have a plastic welder made by the good folks that make Plasti-Fix. I bought the welder to fix stress cracks in a kayak I used to own....it went through a tornado and when it fell out of the sky it landed on a metal t-post.....(I conveniently wasn't in it at the time).

I also have some plastic rods for filling holes and cracks....I'll give it a try on the cut up CX fender and if it works it just may solve your filling problem. Kayaks are HDPE also, I believe..... You may be able to "weld" the plastic if you have a HDPE fill stick (part of the kit from Urethane Supply) and a heat gun. The stress crack in my kayak was easily healed simply by heating it with my HFT $9.95 heat gun......when the plastic turns shiny its melted and can be formed any way you want....might want to have some nice smooth non-rubber gloves on....other wise you leave fingerprints in the plastic not to mention the burned fingers......

I'll let you know what happens.

Sorry I missed you yesterday....

Did your wife tell you that after I gave her the CDI and highway bars I asked her where I should put the motorcycle I brought you to her great surprise (and consternation)?

It wasn't my idea....Dan put me up to it.....:D..........

Victor
I did use my heat gun to soften and bend the forward tips of the tail piece to lay down on the "lobes." I hadn't thought about using it for filling.

If the custom tips in the soldering iron don't work out, I'll give that a try.


R

P.S. Heidi mentioned your joke. She wasn't amused (because it was plausible.)
Just so I am allowed back into Randall's back yard again sometime, Victor is totally responsible! (I sure do wish I had thought of it though!) :cool:

Harbor Freight sells plastic welding kits.
 

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Discussion Starter #10

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Discussion Starter #11 (Edited)
I finally got my camera back from being repaired (Nikon's turn-around was fast. My finding the receipt and sending it to them wasn't.), so I can update with pics.

After dragging my feet all summer, I pulled the linkage apart and cut the modified bracket off the shock arm.


For the XZ550 shock at the height I want, the bolt needs to be here.


But before fabbing the new bracket, I wanted to test fit the YFM350 unit one more time. Without the bracket in the way, it only misses by about 3/16".


The interference is at the corner of the casting. If I push my modification to be only slightly more radical, I might make this shock work after all.


I would need to create a notch 30mm wide and about a 1/4" deep. Most of that is already a void anyway.


If I measure the required depth from the corner, the remainder is about the thickness of the other side of the casting, so I might not compromise the strength of the piece to any great degree.


Hmm... decisions. I like the threaded preload adjuster on the YFM350 shock better than the stepped system on the XZ550. And lining up the bumpers (obscured by the coils), I find a full inch more travel on the YFM350.


After checking prices on eBay, and finding I can get a replacement shock arm for about $25 when I screw this one up, I took the plunge.


And it fits very tidily.


The next step was to work up a template for the bracket.



As it sits now, I have two pieces of 3/16" flat stock cut and waiting to be drilled and shaped. I'll need to file the welds flush on the inside, so I plan to chamfer them with a dremel after they're tacked in place and test fitted. I also need to refit the wheel to check height one more time before final shaping of the brackets.


R
 

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Discussion Starter #12 (Edited)
Of course, now I'll have to find a place to tuck that pesky reservoir. Is it possible to remove it and the hose, and expect reasonable performance from the plugged chamber on the shock itself? Maybe not a great idea.

This is a sealed reservoir with no valve to adjust the gas pressure. I don't even know if it has pressure. Can I replace it with another reservoir that's rechargeable? The fittings appear to be normal banjo bolts.

Any guidance is much appreciated.


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Just so I am allowed back into Randall's back yard again sometime, Victor is totally responsible! (I sure do wish I had thought of it though!) :cool:

Harbor Freight sells plastic welding kits.
Haven't you guys heard of plausible deniability? Dan can't remember because of the pain meds he had to take after the van accident, I swear......

As to trying out the welder on the fender pieces I totally forgot....I'll do it though and report back.

Heidi did register honest consternation/surprise at the thought of a bike being delivered....I fess up...it wasn't Dan, just a spontaneous prank.

Dan, I'd guess its not you that won't be allowed back into the yard....;)...c'est moi.....but if I come back up there will be a CX on my trailer and I'll try again....

Victor
 

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Discussion Starter #15 (Edited)
Yes, I'm way overdue for an update. I have some pics of the mock-up with an empty engine case installed to check for clearance, but not much else has happened (long Winter and busy Spring).

Last Fall, I made some progress with the custom shock mount on the shock arm, but I discovered more interference between the coil and shock link. My next task is to strip the frame again, so I can invert it and actually see what's going on with the linkage. Then I'll cut new templates for the mounting bracket, and make one last attempt before I give up and fit the shorter XZ550 shock. (But I'll sacrifice a lot of travel doing that.)


R
 

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Discussion Starter #17
I started with the GL specifically because the Pro-Link suspension offers a better increase in travel. Every added inch at the shock equals 2 1/2 inches at the axle. I'd never get that with twin shocks.

It's not just added height I'm after, but increased suspension travel.


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Did you figure out the shock reservoir placement?
You can use a longer hose so that you can place it anywhere you choose.
 

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Discussion Starter #19
No, I haven't gotten to that point yet.

The shock I'm trying to use has a sealed reservoir. I assume I can replace it with another that I can recharge? How would it perform with the port capped and no reservoir? I've been hesitant to break the seal until I know those answers.


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As long as it is not part of the casting of the shock, it can be lest off and the shraeder valve can be installed where the hose would attach.
 
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