I'm planning to mount a pair of Rotopax 1 gal containers on the rear rack (well, in that area, anyway). I've heard of issues with weight on the sub-frame, and there are clear markings to limit the weight to 11lbs. A gal of gas is 6 lbs, and a gal of water is 8.3 lbs, for 14.3 lbs, even before strapping down a duffel bag.

So... I want to beef it up. I'm thinking of doing three things, shown in the attached pics...

1) Straight tube from bend in tube surrounding the battery, up to the sub-frame. Triangles are a good thing.
2) Add another bracket to the end of the exhaust to bolt to a bracket on the sub-frame. The exhaust is already bolted on three other points, so why not make use of it's stiffness....
3) Bend up another flat plate, and reinforce the rack mount.

Also have a 351 kit & carb on the way!

What do ya think?

 

Yes on 1, no on 2 - but maybe a piece of plate from your mark to in front on the rear muffler mount along the inside of the tubing and extending below it and on the other side, and 3 can't hurt.
My 2¢.

 

You have it on me. I just bolted on the end of the rack and took off on the Payson DS. Made it to lunch on the A loop, was ready to take the afternoon A loop on back to the trailer when I noticed the rack was a little loose. Lost both bolts out of the rear rack studs (and one of the front side bolts, only one bolt left and it was loose), sheared the flat part of that mount (in picture #2) off, etc. Limped home via the highway. I did take a couple of big hits when the rear stepped out and tried to go to the front, not quite sure what was going on there, but I did hear a big bang & here comes the rear.

I had the tank mounted way back on the rack, which means it was cantilevered off the supports from the frame. I am moving the mounting forward to be directly above where the new weld is. I am thinking that will reduce the bending loads and limit the torsonal vibration on the whole unit.

I just added a 2"wide x 1/8" plate (shaped as an inverted \__/ ), brazed to the remaining ears looking up (where the top plate sheared off) & hoping that will hold.

Your brace on the left side is a good idea, on the right no way to get one in there between the tire & muffler. I guess the muffler could provide some support, but if it bends there will be major problems.

I am thinking adding the pipe brace on the left, I don't think the muffler would be that much of a help. Let me know how yours stands up to the big hits.

 

For what it's worth, I have a 2 gal. rotopax mounted on a cycle rack and I don't have any concerns about my subframe. I rode with it full along with a big drybag strapped on top of it for a 3 day ride offroad ride and didn't have any problems. The cycle rack has extra support that attaches lower on the bike.

normal mode:



super load:

 

I like the piece of mind that bracing might bring you, but I have hauled 1gal fuel, 1gal water, and camping gear for significant distances through some reasonably gnarly terrain without any indication of weakness or stress on the subframe.

 

Loaded that thing up just a little over the rated limit several times now, and the going wasn't always easy. Never any whoops with this load though. I think the '06's are a little stouter than the '09+. Did a thorough check a year ago after these rides and NO signs of stress that I could find.



I did pick up an almost-used cycle racks for the next heavy-load adventures.

 

I can see some subframe bracing in my future, never realized that much of the rear section was unsupported. I'd rather not deal w/ a broken subframe on a trip somewhere.

My Outback rack does tie into the rear footpegs, transferring weight and controling the downward twist force on the rear of the subframe. I'm worried about the shear force right in front of the seat bolts.

The Cycle Rack is a good design, basically doubles the amount of metal carrying the weight and triangulating. Perfect for the Giant Loop.






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Actually, looking closer at it, it appears the left seat bolt is in front of the braced section and right seat bolt has a gusset over the top of it. Still, an ounce of prevention....


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A buddy of mine here experienced failure at the seat bolts, the welded nuts busted lose so he has to do major surgery from underneath/behind to take the seat on/off to get to the air filter. PITA...

 

I know we see pics of people in 3rd world countries riding 3-4 people on a little bike with a ton of items strapped to the bike. Of course we don't know how long the frame and components are lasting on some of those bikes. That said, the KLX probably isn't the proper platform for regular and consistent heavy load traveling. It's really designed more dirtbike than touring bike. I'm pretty sure if one keeps loading down this bike at the rear that sooner probably more than later you'll have subframe issues...unless all your travel is on relatively smooth pavement. But at that point, why use this bike for just pavement?

The big modification on the Kawasaki KLR600/650 series occurred with the 650 model in '87. It's also why the weight jumped so much on that model. Kawasaki saw the handwriting on the wall as to what people were doing with that bike. And even though the subframe was substantially beefed up on the 650 series, you still had to do a bolt modification for even that beast of a subframe to survive. Our subframe is somewhat wimpy, and it's just the nature of the kind of bike it is, no so much a failure in design. I don't travel off my KLX, but I do go way out in the boondocks and need to have items for overnight survival and bike repair to some degree. I've tried to spread the weight around from the front fender, headlight number plate, side covers, large backpack, and a medium bicycle rack bag on the factory rear '06 rack. This way the bike still handles pretty well too. I don't know...IMO this just isn't a good choice for a touring bike. But...like those folks in 3rd world countries, it's possible to try anything.