I Unearthed a Bonanza While Craving a Taco

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Geno Ferrari

New Member
#1
#1
Although I have been looking for a buildable 22 frame, I now am a contented member of the Bonanza Boys. I bought a Bonanza vintage frame ( serial #39734 stamped on the badge on number plate on the forks) that has no suspension on the forks, and it looks like someone clipped the ends of the swing arm and welded them to the rear up tubes. The frame seems to be in good shape other than its conversion to a hardtail. I'm not restoring this bike to pristine original condition, and I simply want to make it a good everyday rider. But I definitely am going to suspend it both front and rear. In addition to a swing arm, rear shocks and swing arm shaft, I am going to need a jack shaft, sprockets, and retaining hardware. Plus I need to figure out how to get some suspension on the forks. Any ideas would be deeply appreciated.
There must be a Ben Cartwright out there that oversees the Ponderosa of Bonanza parts. I would like to avoid using the aftermarket stuff sold by Hop Sing, but that's a Hoss of a different color. I'm looking forward to this build, and Happy Holidays gentlemen.

Geno
 

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6doggie3

6doggie3

Well-Known Member
#5
#5
Nice find on the Bonanza! Not sure what model you have but I never seen unsprung forks with bent bars?
Do you have any more pics? And are you keeping the "HOP SING"motor? LOL
 
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Geno Ferrari

New Member
#8
#8
I'm getting the feeling that the forks aren't from the Ponderosa, even though they have the Bonanza badge. As for the Predator, I will eventually add a billet flywheel and con rod. Even though I bought it new a few months back, I can't explain why the device that limits the RPMs seem to be missing. I will testify that I did inhale, but I don't recall anything about the "rev limiter". So, for now during speed runs, I open it up and count to five before I employ the "chicken lift". Since we are both from the Greater Sacramento area, we know what it is like to be without a governor after Arnold got caught doing his maid.
 
Stangrcr1

Stangrcr1

New Member
#9
#9
Geno, TH and Bonanza forks are almost identical. Drill 3 holes in the TH forkplate and rivet the badge, and you have Bonanza forks.

The reason they look TH to me is about 1" below the top of the fork plate, it looks like there are holes in the sides of the fork tubes. This was the point where TH fork springs are bolted in. Bonanza forks didn't have this hole, AFAIK.
 
markus

markus

Well-Known Member
#10
#10
Stangrcr1 said:
Geno, TH and Bonanza forks are almost identical. Drill 3 holes in the TH forkplate and rivet the badge, and you have Bonanza forks.

The reason they look TH to me is about 1" below the top of the fork plate, it looks like there are holes in the sides of the fork tubes. This was the point where TH fork springs are bolted in. Bonanza forks didn't have this hole, AFAIK.
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Sure they did, at least the suspended forks. thats how the springs were held in place. Some of the TH models even had 2 holes (I think mostly the chrome forks) as they offered them with externally mounted Sebac shocks instead of the internal springs. Those on the bike look bonanza to me they just had solid lowers grafted on, Look a the forkplate, it does not run in parallel with the forks, trail horse bikes did. While they probaby are bonanza they are not original to that frame as its a MX/MB style frame, one reason the overal rake is funky.
 
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Geno Ferrari

New Member
#12
#12
You guys are probably both on the money. The major reason that it sits a horse with his balls dragging is some previous owner cut the ends of the swingarm and made the bike into a hardtail. Why? It takes all kinds. I cut the ends off of the up tubes, and am currently designing and fabricating another swingarm. The forks though, any suggestions as to what I should do to suspend them? Can I find TH or Bonanza springs that can be inserted into the existing forks? Or, do I get forked by forking out cash for some spring forks?
 
markus

markus

Well-Known Member
#13
#13
first thing I would do is strip the paint off the lowers and see if you can figure out where they spliced it in. Then hope all they did was inert a tube and weld at the seam only. Bonanza forks are cut pretty high up so you you don't want to go too far up past that point so there is more upper for the lowers to sit in (don't want them folding over), you also want to look real good to see if there were a bunch of divots or bends form straightening or anything like that....stuff that would misshape the inside of the tubing.

If you can get whatever they installed to convert out of the inside of the forks and have clean tubing on the inside, you can just buy bonanza lower assy's and bolt them in
 
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Geno Ferrari

New Member
#14
#14
Thanks Markus. That makes good sense. Stupid question #1: I can't figure out what "TH" stands for? Stupid question # 2: Is there any chance that the forks are not Bonanza or TH, or that they didn't have springs originally? After I read your reply, I went out and sanded one side from number plate to the pressed end axle slot and I'll be damned if I could find any trace of a weld or joint.
 
Stangrcr1

Stangrcr1

New Member
#15
#15
TH = Trail Horse. Very similar bike to a Bonanza.

The BC 1000 had forks similar to that, but shorter length.

Did someone try to make a Scout out of parts?
 
markus

markus

Well-Known Member
#16
#16
splices can be tough to spot. I cut 4" out of this frame so a kart engine would not look so tiny in it, sleeved, then welded the 3 pieces together at the seam lines, and ground it all back. Its pretty hard to tell even still in bare metal shown in the last photo:





gotta look for maybe an area with some deeper scratches that are filled with primer or an area that that may have a couple of lower spots or pin holes,. I would bet your really going to have to hunt for them. you could maybe run a fish tape down through the ends of the bars and see if you can get a rough measurement when you hit a snag or lop the ends off the bottom and try to spot it from there. Got nothing to loos unless you think you can make use of the forks the way they are :thumbsup:
 
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Geno Ferrari

New Member
#17
#17
Impressive welds hidden well-I can only guess at where they are. And no, Markus, I am too damn old to be riding without front suspension, so I can't or won't use the forks as is. I've rebuilt a set or two of forks on dirt bikes, which consisted of seals and fluid replacement, but I never seen nor had mini bike forks apart. I am not sure how the lowers attach inside to the uppers, or what retains the springs, which is going to spawn stupid question #3: If I lop off the ends of these forks, something has got to be available to get a set of springs attached, correct? Since the bike was already altered when I got it, I'm not going pure Bonanza anyway. So, somebody has got to make or have made a set that I can paste to the bottom of these forks? Thanks again by the way-you have been a big help. Also, I noticed that you thankfully, didn't throw that old cliché out about that there is no such thing as a stupid question. I've been a Senior English teacher at a high school for 38 years, and I have heard some very stupid questions. Of course, I maintain a poker face and don't laugh out loud at the kid who said it, nor do I roll my eyes when I hear one. A month ago, I had a young lady who has been accepted to University of Texas, ask me, after reading an article of possible causes of the tragedy, if anyone died when the Titanic sunk.
 
markus

markus

Well-Known Member
#18
#18
They actually make repop bonanza fork lowers, I'll give you a link to the entire suspension parts page, look at the picture of the shocks also available to get an idea of actually how the lowers will look when put together as they are shown disassembled.

Bonanza Mini Bike Parts - Forks, Springs, Shocks

again though you definitely need a clean run up the forks for the lowers so they will articulate and not get hung up so before investing in the lowers you do want to verify your not going to run into major problems.

I don't have any Bonanza frames here anymore, but maybe someone that does will be nice enough to give you a measurement front he bolt hole that holds the inner to the upper (the hole just south of the upper part of the forkplate) down to the bottom of the tube. Maybe just cut a hair about it and see whats there. your really do want to keep the upper section as long as you can one other issue is that with the increased rake its going to wear more and you want as much solid inner up into the upper as you can get.

I don't know of any parts breakdown/explosion pictures of bonanzas but they are all pretty much the same so this should at least give you an idea of how its set up:

View attachment 66512
 
6doggie3

6doggie3

Well-Known Member
#19
#19
Geno Ferrari said:
Although I have been looking for a buildable 22 frame, I now am a contented member of the Bonanza Boys. I bought a Bonanza vintage frame ( serial #39734 stamped on the badge on number plate on the forks) that has no suspension on the forks, and it looks like someone clipped the ends of the swing arm and welded them to the rear up tubes. The frame seems to be in good shape other than its conversion to a hardtail. I'm not restoring this bike to pristine original condition, and I simply want to make it a good everyday rider. But I definitely am going to suspend it both front and rear. In addition to a swing arm, rear shocks and swing arm shaft, I am going to need a jack shaft, sprockets, and retaining hardware. Plus I need to figure out how to get some suspension on the forks. Any ideas would be deeply appreciated.
There must be a Ben Cartwright out there that oversees the Ponderosa of Bonanza parts. I would like to avoid using the aftermarket stuff sold by Hop Sing, but that's a Hoss of a different color. I'm looking forward to this build, and Happy Holidays gentlemen.

Geno
Click to expand...
Where did you find the mini CL ,Ebay, friend? Slim pickens in Nor Cal for mini bikes this past year!
 
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Geno Ferrari

New Member
#20
#20
Sorry 6Doggie3, I am not sure you are asking me-Geno Ferrari-because I was told what I got was a MB or MX; Either way at this point, I don't know BM from Shinola, but I learn quick. I'll answer the question as if it was directed at me: I bought a kit home built last summer from guy who puts ads on Craigslist all; the time. I told him I was looking for a taco or bonanza. and a few months later, he came up with the frame I bought. he has more bonanza stuff including a frame without forks. If you want his number let me know.
 
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