Honda CR500 frame rust/cancer.

socalsand
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socalsand
Edited Date/Time 5/17/2018 4:29am
I have a 95 CR500. Perfect running bike that I ride desert with. Been hesitating breaking down the bike for a frame repair and full resto while in the process.
Bottom side of frame has a rust through spot on both frame rails. What’s your opinion on fixing and what process would you use to repair it?
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kb228
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kb228 5/15/2018 1:14am
5/15/2018 1:14am
Cut away the rot and reweld it & Hope its safe to use lol l
TrailDigger 5/15/2018 3:19am
5/15/2018 3:19am
Grind out the rust with a wire wheel and seal it with an epoxy. Then weld a piece of flat stock molded around it over the section. Would be stronger than new and not cutting the frame.
socalsand
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socalsand 5/15/2018 11:21am
5/15/2018 11:21am
TrailDigger wrote:
Grind out the rust with a wire wheel and seal it with an epoxy. Then weld a piece of flat stock molded around it over the...
Grind out the rust with a wire wheel and seal it with an epoxy. Then weld a piece of flat stock molded around it over the section. Would be stronger than new and not cutting the frame.
Thanks for the info! That was my thought, a guy who restores bikes said he would cut the section out and fit in a piece and reweld it. I don’t like the idea of cutting the frame if not absolutely necessary.
TrailDigger 5/15/2018 12:25pm
5/15/2018 12:25pm
socalsand wrote:
Thanks for the info! That was my thought, a guy who restores bikes said he would cut the section out and fit in a piece and...
Thanks for the info! That was my thought, a guy who restores bikes said he would cut the section out and fit in a piece and reweld it. I don’t like the idea of cutting the frame if not absolutely necessary.
You could do that to minimize rust, but I’d weld another piece over it and maybe the opposite rail to match it.

Frames do flex, especially steel ones, and I wouldn’t trust a cut and welded section to hold up to any big jumps or crashes.

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socalsand
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socalsand 5/15/2018 3:44pm
5/15/2018 3:44pm
I agree. I could probably use 1/8” flat stock, heat and bend around to fit solid then weld around the ends.
sandman768
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sandman768 5/16/2018 5:10am
5/16/2018 5:10am
Find a good welder/ fabricator shop...this is nothing for a good shop...I have had rails replaced/ repaired many times...have them chase all the lower cradle & footpeg mounts also.... They would appreciate you having the lower cradle area sandblasted first ...
Here is a frame I had repaired ....include the engine mounts bolts so the welder can align the rails when welding.... I also make my own skid plates for the chromoly frames, very ez to do & having the skid plate welded in also strengthens the lower frame assy... If done correctly you will never have to do it again....
socalsand
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socalsand 5/16/2018 9:55pm
5/16/2018 9:55pm
sandman768 wrote:
Find a good welder/ fabricator shop...this is nothing for a good shop...I have had rails replaced/ repaired many times...have them chase all the lower cradle &...
Find a good welder/ fabricator shop...this is nothing for a good shop...I have had rails replaced/ repaired many times...have them chase all the lower cradle & footpeg mounts also.... They would appreciate you having the lower cradle area sandblasted first ...
Here is a frame I had repaired ....include the engine mounts bolts so the welder can align the rails when welding.... I also make my own skid plates for the chromoly frames, very ez to do & having the skid plate welded in also strengthens the lower frame assy... If done correctly you will never have to do it again....
Yeah that looks real good. I guess I’ll be looking for a good fab shop. I’d like to have all new fresh metal in there like yours rather than patch work as well. Skid plate looks pretty good welded in as a whole.
Thanks for the info and pictures....Doug.
mxracer666
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mxracer666 5/16/2018 10:29pm
5/16/2018 10:29pm
I have gotten some high-quality chrome moly steel tubing. cut it in half and welded the piece onto the bottom half of the OEM frame tube. Also, figure out how the water is getting in there in the first place and causing the rust! I think most steel frames have a small (1/8" size) hole drilled in the bottom to let water drip out -- often tho, these holes get plugged and water builds up!
socalsand
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socalsand 5/17/2018 1:24am
5/17/2018 1:24am
mxracer666 wrote:
I have gotten some high-quality chrome moly steel tubing. cut it in half and welded the piece onto the bottom half of the OEM frame tube...
I have gotten some high-quality chrome moly steel tubing. cut it in half and welded the piece onto the bottom half of the OEM frame tube. Also, figure out how the water is getting in there in the first place and causing the rust! I think most steel frames have a small (1/8" size) hole drilled in the bottom to let water drip out -- often tho, these holes get plugged and water builds up!
Correct, it does have relief holes in the bottom. this bike was owned by the same person for 20 yrs and a relatively a low hour bike, but set for a long time between rides. Others have stated that this is a common issue with these Cr frames. I was hoping for a fix without stripping to bare frame. Looks like a full resto coming.
TrailDigger 5/17/2018 3:20am
5/17/2018 3:20am
You could have it welded and then fill the inside with seam sealer?
socalsand
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socalsand 5/17/2018 4:29am
5/17/2018 4:29am
TrailDigger wrote:
You could have it welded and then fill the inside with seam sealer?
If I had it welded I’d still want to strap it.

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