Suzuki GN125 Bent Frame Solutions

Idle Ender

Member
So, about a month ago I bounced off the front of a van on the ol Suzuki. Snapping my leg in half and bending just about everything that can be bent on the bike. Mostly small, cosmetic issues. But a few things are a BIG problem. The frame is bent near the forks and the swing arm is goobered beyond repair. Normally Id total it out and pop the engine on a go kart or something, but this bike has sentimental value and Im determined to keep it on the road. Sure, I can get a new swing arm fairly cheap, but the frame needs finessed back into shape or replaced. On a small/slow bike like that Im not particularly concerned with it being dead on perfect and I can fudge the VIN over to an untitled frame no problem. FINDING ONE seems to be the issue. Anyone happen to have a bare frame and/or swing arm lying around? Lol. Or even any insight or ideas? Much appreciated.
 

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Rider52

Active Member
East Coast - G.M.D. COMPUTRACK Atlanta
West Coast - Dr. Johns Motorcycle Frame Straightening (Jap frames are $400 minimum)
I've used Dr. Johns and a friend had her BMW frame done at GMD both excellent.
 

Luugo86

'73 CB350, '78 XS650 Cafe Killer
Sorry to hear about your accident. Hope everything works out, that's a very cool little bike.
 

Idle Ender

Member
Rider52 said:
East Coast - G.M.D. COMPUTRACK Atlanta
West Coast - Dr. Johns Motorcycle Frame Straightening (Jap frames are $400 minimum)
I've used Dr. Johns and a friend had her BMW frame done at GMD both excellent.
Thats a bit pricey for me, but its good to know theres professional options out there. I was thinking Id either eyeball it back into shape myself with a little wrestling or buy a cheap parts bike for $1-200 if I can find one. Theres a large motorcycle junkyard of sorts near where Im at that Ive been meaning to check out. This seems like a pretty good excuse.
 

Idle Ender

Member
Luugo86 said:
Sorry to hear about your accident. Hope everything works out, that's a very cool little bike.
Thanks, I appreciate it. Im just now starting to walk again. Lol. So I might as well get right back on a bike. Its a shame these are so difficult to find in the US.
 

ridesolo

You only bear responsibility for your own actions
Idle Ender said:
Thats a bit pricey for me, but its good to know theres professional options out there. I was thinking Id either eyeball it back into shape myself with a little wrestling or buy a cheap parts bike for $1-200 if I can find one. Theres a large motorcycle junkyard of sorts near where Im at that Ive been meaning to check out. This seems like a pretty good excuse.
I'm sorry to hear about your accident. I certainly understand the sentimental aspect, but I'm not sure I'd be comfortable riding a straightened frame. Perhaps pulling curb kinks out of the down tubes of an irreplaceable/collectable classic, but a bike that could be a daily rider/commuter? Not so sure about that, especially because it's that large backbone. Others on here are far more experienced than I when it comes to metal working, their opinions could be different than mine, but if my bike had a frame bent like that I'd be looking for a replacement frame.
 

teazer

Well-Known Member
DTT BOTM WINNER
Sorry to hear that you were nailed by a van.

The simple solution is a frame swap of course and take care of whatever legal issues arise from that.

As to straightening frames, it can be done and quite simply if there is no structural damage. That means no cracks and no crushed tubes. I have seen many frames straightened on jigs to closer that factory tolerances and at a Superbike school I watched a couple of strong men with long steel tubes, push/pull a steel Kawasaki 600 back to more or less straight. On that one the from end was twisted. Steel frames are not hard to straighten if you take your time.

The last frame I had straightened professionally cost $750 and needed to be done on a jig. Aluminum frames tend to crack at the weld joints, so they are a bit more tricky, but steel is easy.

That one looks banana type bent but I suspect that if you put the top tube in a press, you could push it straight. Steel has a certain elasiticiy and will spring back, so you have to go past straight to let it spring back, but take your time and check everything carefully.

My concern would be that if the top tube and swingarm are bent, what else has also been bent. The front downtube is most likely tweaked and the back end is probably bent too. Start by checking wheel alignment and see how far out it is. With wheels in line, both wheels should also be vertical. I suspect that the front wheel on that bike is off to the right and skewed at an angle.

But you have nothing to lose by checking it and trying to push it straight (with the engine still in place) and if it's too bad, all it cost was some time.
 

Idle Ender

Member
teazer said:
Sorry to hear that you were nailed by a van.

The simple solution is a frame swap of course and take care of whatever legal issues arise from that.

As to straightening frames, it can be done and quite simply if there is no structural damage. That means no cracks and no crushed tubes. I have seen many frames straightened on jigs to closer that factory tolerances and at a Superbike school I watched a couple of strong men with long steel tubes, push/pull a steel Kawasaki 600 back to more or less straight. On that one the from end was twisted. Steel frames are not hard to straighten if you take your time.

The last frame I had straightened professionally cost $750 and needed to be done on a jig. Aluminum frames tend to crack at the weld joints, so they are a bit more tricky, but steel is easy.

That one looks banana type bent but I suspect that if you put the top tube in a press, you could push it straight. Steel has a certain elasiticiy and will spring back, so you have to go past straight to let it spring back, but take your time and check everything carefully.

My concern would be that if the top tube and swingarm are bent, what else has also been bent. The front downtube is most likely tweaked and the back end is probably bent too. Start by checking wheel alignment and see how far out it is. With wheels in line, both wheels should also be vertical. I suspect that the front wheel on that bike is off to the right and skewed at an angle.

But you have nothing to lose by checking it and trying to push it straight (with the engine still in place) and if it's too bad, all it cost was some time.
Right. Thats obviously the easy route if and when I find a parts bike/frame. Im currently on the hunt. But like you say, its worth at least trying to iron out the frame. Getting a good look at it, it all seems doable with enough leverage and patience. The tail end of the frame doesnt seem damaged, and what is bent up front is smooth. No cracks or crunches. Did they use heat when you watched them straighten that frame? I consider it, but worry about the integrity of the steel. I plan on taking a ton of measurements and getting a real good look at it before making the call. Also, both wheels are all out of whack, which tipped me off to the damage to begin with. For a few weeks after the accident, I had only seen it through my window and everything looked cosmetic. It wasnt a super serious accident. I was going like 20mph and the van was stationary (long story). Point is, I was disappointed but not surprised when I noticed the wheels were tweaked. Lol. Could have rode a little more this season!
 

teazer

Well-Known Member
DTT BOTM WINNER
No heat needed if you use a press. If you try to use long steel tubes and a couple of strong mates, heat might help. Heat isn't usually required and it makes it a lot more complicated to hold/bend because invariably someone will end up touching the heated part.

Cold pres it in a 10Ton hydraulic press. It will have to be supported by a couple of mates as you "drive" the press ram.
 

Rider52

Active Member
This EBay seller is parting out a GN125. The parts listed are everything but the frame, but he may have that too! Won't hurt to ask him https://www.ebay.com/usr/yz12910rv
 

Idle Ender

Member
teazer said:
No heat needed if you use a press. If you try to use long steel tubes and a couple of strong mates, heat might help. Heat isn't usually required and it makes it a lot more complicated to hold/bend because invariably someone will end up touching the heated part.

Cold pres it in a 10Ton hydraulic press. It will have to be supported by a couple of mates as you "drive" the press ram.
Im just trying to figure out the logistics of that. Lol. Never tried this before. Would it be easier to tear it down to bare frame?

Rider52 said:
This EBay seller is parting out a GN125. The parts listed are everything but the frame, but he may have that too! Won't hurt to ask him https://www.ebay.com/usr/yz12910rv
I shot them a message, so well see. They have a suspicious amount of GN125 parts, so chances are they were all from a parts bike at one point. Parts bikes usually have frames!

I also had a mad scientist idea late last night. I found a crusty old Rickman frame with the tank on facebook dirt cheap. Itd take some doing, but imagine a sick "Rickman Suzuki" enduro.
 

ridesolo

You only bear responsibility for your own actions
Idle Ender said:
I also had a mad scientist idea late last night. I found a crusty old Rickman frame with the tank on facebook dirt cheap. Itd take some doing, but imagine a sick "Rickman Suzuki" enduro.
Do it!!!!
 

teazer

Well-Known Member
DTT BOTM WINNER
Yes, strip it down but leave the engine bolted it or else the frame will distort even more.

RIckman enduro frame would be a huge upgrade and a fair amount of work, but go for it.
 

Idle Ender

Member
teazer said:
Yes, strip it down but leave the engine bolted it or else the frame will distort even more.

RIckman enduro frame would be a huge upgrade and a fair amount of work, but go for it.
Gotcha. Ill see what I can manage.

The Rickman Zundapp I have eye on is literally just the frame, tank, rear wheel, swingarm, and forks. All of it is super crusty and rough. Itll be tough and EXPENSIVE sourcing parts in this part of the US. As much as I would like to. Lol
 

Idle Ender

Member
To anyone interested, I FOUND ONE! And not just any old replacement frame. A complete bike with just a hair over 800 miles! It even came with a ton of paperwork from the single owner. In the process of swapping all my parts over now. Spent the cold days tearing the old bike down to the frame in my living room. Going to put a 150 kit and some go-fast junk on the higher mile engine before swapping it to the new frame and tucking the low mile engine away. The new engine runs great with my rebuilt carb slapped on it. Smooth as silk. Only issues with the new bike are the front brakes are locked up/missing front caliper, the carb needs rebuilt, and the tank is trashed (rust and dents everywhere.)
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Definitely recommend this to you single folks out there. Was a very relaxing experience. lol.
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Just a little bent. No big deal.
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Jimbonaut

Well-Known Member
DTT SUPPORTER
I like to think my wife would be ok with me wheeling a bike into the living room and getting deep down and dirty with the thing. I like to think that. But the reality would be different. Very different. Like ecstatic is to losing-her-shit different.


Sent from my iPhone using DO THE TON
 

Idle Ender

Member
It lives!! Spent the afternoon swapping everything over from the old bike, including the unobtanium GS125 forks which are thankfully not bent. The new AGM battery for it even came 3 days early so I didnt have to bump start it for my test ride! Rides like a dream. Just waiting on my repop tank and side covers from China. Theyll get here when they get here. Lol

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