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Discussion Starter · #1 ·
After 3 years of thrashing, my ninja 250 sidecar frame broke. It had been handling weird for a couple days, and on a spirited ride in the mountains with the lady, I ripped out every tube connecting my forks to the steering tube.

Somehow nobody got injured. And I’ve reinforced the new frame in hopes of it not happening again.
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Welded only to roll the bike around
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Discussion Starter · #2 · (Edited)
I added supports to the new frame, put in tapered steering bearings, remade an attachment for the sidecar, and put a stiffer shock on the sidecar. It’s been riding really great. 100,000 miles and the last 15k with a sidecar was just too much for the old frame the way I drive it.

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Discussion Starter · #4 ·
She was putting on a bit of a show for the camera. But I did treat her to some chicken and waffles afterwards to beg for forgiveness.

Almost nailed that tree though. Got lucky with sticks and gravel to stop the bike

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Discussion Starter · #6 ·
big tree's, redwoods in Rotorua NZ are like that
I’ve always wanted to visit New Zealand, heard a lot of good things from there. It would be my first choice for relocating if I wanted to leave the states.

This is on Mt Tamalpias, not far from San Francisco, CA. The last 15 minutes before this had a steep drop on one or both sides of the mountain. It could have ended very badly.
 

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Yikes never seen that happen before, glad you guys are all right!
 

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Dude! You're right around the corner from me! I'm in Oakland.

I never thought I'd say this, but that's a cool AF little Ninja 250.

I'm also somewhat of a sidecar guy - my wife & I had a Ural for a year when we lived in central Asia.

Clarification: it DIDN'T break all at once: if you look at one of the horizontal tubes, you can see the broken area is rusty. This was a small failure left un-repaired that cascaded into a major failure.

Big question is -- did the tubes themselves break where the gusset came off? That's usually a sign of 3 things:

1) weld embrittlement, which a common problem if the tube is a medium carbon steel such as 4140 cro-moly (unlikely that alloy, but possibly some mongrel alloy that resembles 1040 that has enough carbon to harden when welded)

2) feeding loads into a weld in shear across the weld instead of in line with the weld. Was there a sidecar mount on the steering head gusset? It doesn't look like it.

3) one or more of the parts is vibrating -- the gussetted area becomes a more-rigid point, and the vibration causes the area just outside the weld to act like a hinge, which eventually fatigues and breaks.

Regarding #3, the single most common source of rogue vibration is loose engine mounts.

I think the frame is basically scrap at this point... except the head tube with the VIN.

IMHO, you have wildly exceeded the design brief for the chassis. Kawasaki probably said, Naah, nobody in their right mind would put a hack on a 250 (congrats, wear that badge of honor proudly) and sized the tubing for anorexic teenagers. Even if you were to glue this thing back together with new, bigger, better braces, the tube would just fracture like it did before.

Again, IMHO, if you love the platform, and love the bike, your best way forward might be to fabricate a new, stouter chassis. It's also an opportunity to make improvements for your intended use such as integral hack mounts, different steering geometry, bigger or newer engine, widen things for a car tire, etc. Even a leading link front end could go along with the project.

I can help with advice, etc.
 

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Discussion Starter · #11 · (Edited)
Dude! You're right around the corner from me! I'm in Oakland.

I never thought I'd say this, but that's a cool AF little Ninja 250.

I'm also somewhat of a sidecar guy - my wife & I had a Ural for a year when we lived in central Asia.

Clarification: it DIDN'T break all at once: if you look at one of the horizontal tubes, you can see the broken area is rusty. This was a small failure left un-repaired that cascaded into a major failure.

Big question is -- did the tubes themselves break where the gusset came off? That's usually a sign of 3 things:

1) weld embrittlement, which a common problem if the tube is a medium carbon steel such as 4140 cro-moly (unlikely that alloy, but possibly some mongrel alloy that resembles 1040 that has enough carbon to harden when welded)

2) feeding loads into a weld in shear across the weld instead of in line with the weld. Was there a sidecar mount on the steering head gusset? It doesn't look like it.

3) one or more of the parts is vibrating -- the gussetted area becomes a more-rigid point, and the vibration causes the area just outside the weld to act like a hinge, which eventually fatigues and breaks.

Regarding #3, the single most common source of rogue vibration is loose engine mounts.

I think the frame is basically scrap at this point... except the head tube with the VIN.

IMHO, you have wildly exceeded the design brief for the chassis. Kawasaki probably said, Naah, nobody in their right mind would put a hack on a 250 (congrats, wear that badge of honor proudly) and sized the tubing for anorexic teenagers. Even if you were to glue this thing back together with new, bigger, better braces, the tube would just fracture like it did before.

Again, IMHO, if you love the platform, and love the bike, your best way forward might be to fabricate a new, stouter chassis. It's also an opportunity to make improvements for your intended use such as integral hack mounts, different steering geometry, bigger or newer engine, widen things for a car tire, etc. Even a leading link front end could go along with the project.

I can help with advice, etc.
Oh hey! I make it to Oakland pretty often, keep an eye out for the sidecar. I just looked back and didn’t specify that I got a new frame, and the second group of pictures are the new frame I reinforced.

Yeah, I thought back, and remember some handling issues the 2 months leading up to it. One tube for sure broke the day before, I noticed more handling issues, and the next day something was squeaking (it was a tube rubbing against its broken self). I also had forgotten that I crashed this once without the sidecar, and bent the forks and triple tree a few years ago. The frame probably got stressed from that.

The horizontal tube kinda looks rusty where I welded it back together, but that’s the residue I get from my welding, kinda always looks rusty.

The head tube just wasn’t design to be twisted, steering with a sidecar puts crazy side loads on it, and as you said, this frame wasn’t designed for anything near this. I’m hoping that tying the tubes together on my new frame will better help distribute the load, instead of breaking them off one at a time.

You’re right about my motor mounts being loose. I forget I have to tighten them periodically, they just vibrate loose.

In the past, the sidecar mounts were not as secure, causing speed wobbles, and loading the individual tubes weird when others werent mounted so ridgid. I’ve fixed all those this time around.


I think the main cause it broke is that I thrash the living fuck out of the bike. I have no idea how it made it 3 years. I’ve slid the front end so much trying to catch cars on back roads with a passenger hanging off the side. So many deep pot holes on 101. I carry heavy loads sometimes. Its really abused, and I feel it needed to die to become stronger with a new frame.

If you’d ever like to check out the bike and offer up some advice let me know. You’d probably like my project car too.
 

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I think the gussets will help, but just make it live longer before meeting the same fate. As you suggest, sidecars need to be hella stout in the steering head.

One thing you could do would be to skin the whole "backbone" in sheet metal which turns the whole thing into a triangle. That would take work to figure out coil mounts, tank interference, etc.

Safety wire the motor mounts! Or at least get some elastic lock nuts.

I'd dig a get together. Two of my buds do varied levels of customizing, so maybe we could do a little garage party, if that works for you. I know they'd love your bike. @Dirtbaggabe
 

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Discussion Starter · #13 ·
I think the gussets will help, but just make it live longer before meeting the same fate. As you suggest, sidecars need to be hella stout in the steering head.

One thing you could do would be to skin the whole "backbone" in sheet metal which turns the whole thing into a triangle. That would take work to figure out coil mounts, tank interference, etc.

Safety wire the motor mounts! Or at least get some elastic lock nuts.

I'd dig a get together. Two of my buds do varied levels of customizing, so maybe we could do a little garage party, if that works for you. I know they'd love your bike. @Dirtbaggabe
Meant to reply sooner but got busy with work and projects. Feel free to shoot me a text, and we can find a day to meet up

Maurice
408-648-6919
 

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Discussion Starter · #15 ·
I can tell you what I’ve learned about sidecars.

My frame isn’t ideal, most sidecar attachments should have one attachment low on the frame in front or close to the engine, along with 3 other attachments. You can find universal attachments online and look at other setups for ideas. most other attachments are adjustable too. Mine are mildly, but I’ve made them even more rigid lately

I made the frame for it, and used the same swing arm as the ninja 250z the load on the sidecar can be a lot in cornering, especially with a passenger. I went with a stiffer shock at first and had another adjustment hole to raise it for passengers. Recently I put in a much stiffer shock from a gsxr 1000. Kinda stiff when empty, but it was the right call. Some people don’t run suspension on a sidecar.

Steering wobble. Somehow mine went away after the more rigid mounts. But almost all sidecars suffer from a low speed steering wobble. Changing steering angle, and lean all affect at what speed and how violent it happens, but plan on running a steering damper.

Drag is your enemy with the sidecar. My windshield on my sidecar costs me about 5mph. It also makes me fight it on the freeway, and my arm gets sore after a couple hours. You can compensate with the alignment setup

there’s a page on the internet with how to do a proper setup. I think I need to readjust mine in fact. The moto should lean slightly away from the sidecar - assuming the sidecar is on the right, and you drive on the right side of the road. It makes it better for the crown in the road. Straight up and down can work too. I think the toe in of the sidecar wheel helps with pulling on the freeway, at the expense of eating the tires more. Another thing I would have never known, but placement of the sidecar wheel fore and aft, has different benefits. I can’t remember which way, but one helps it at high speed stability, the other helps it scrub more and not lift up into the air when cornering.


Okay here’s all the bad stuff about owning one:

It’s hard to lane split - I’ve done it… I don’t recommend it. But it may stick you in traffic

There’s a learning curve to riding it. That sidecar wheel can come up in the air easily, changing your line, and throwing you into the other lane in a corner. Turning away from it is amazing though, you can rail it super hard.

If you ride hard in the mountains it’ll eat the back tire. My last one has lasted me a little longer because I got a touring tire. But it EATS the tire. Could also be my poor setup.

The Pro’s
You can haul a lotta stuff. A person with groceries and a massage table strapped to the back of the bike, with my tools is the most I’ve hauled. My bike was slow and my steering heavy, but it’ll do it.

You’ll feel massively cool

You practically cant fall over, I don’t even ride with tons of gear anymore

If you tour, you don’t have to get panniers, strap anything down, tuck things away etc. throw your stuff in and go.

You can lock tools in it and keep it with you all the time

Anyway. Sorry for rambling. Any specific questions

Damn, if you can run a sidecar on a 250, my 900 should certainly have no problems at all!

Do you have any more details on the sidecar setup?
 

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Is a 4 point mount necessary? I've seen/read about leaning setups.

I dont know 100% that I'm going to do this with my CB900, I might keep the CB as a metric version of a RoadGlide, and then look at a 'Wing or Voyager to run a sidecar off of instead.

The CB has been great for in town and sub-80mph riding. The few times I've had it on the interstate, it sees like it doesn't have enough OOMPH to pick up much more on the highway. Seems like the WindJammer is just too much of a sail against the wind for the 900. At least if I want much more than 80-85.

Then again, the CB900 is on the heavier side.
 
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