Are you sure the part is through-hardened ? I do not know the geometry of the kicker arm on an old Indian. Is it the kind that incorporates a sector gear that is out in the open ?
My own guess is the part may be made from a fairly low carbon steel. I would guess that given the application, the part might have been a low-carbon alloy steel forging that was machined where needed, then "case hardened" or carburized and quenched. This would give wear resistance on the gear teeth and pivot points, as well as increasing the strength of the arm in bending. The surface hardening process would enable the arm to resist shock or impact loads, as would be experienced on an Indian Motocycle.
I would say there are two major approaches:
-Live with the kicker arm as it is. If it works and kicks over the engine, and the motorcycle is not to be a museum quality restoration, or a "rider", consider leaving the arm as-is.
Whichever approach you take, I recommend you consider the following:
Given the damage to the arm and the service it sees (kicking over a 4 cylinder Indian engine), my own recommendation is to do some sort of non-destructive examination. At the simplest, a good cleaning and visual inspection followed by dye penetrant testing should be done. Something like magnetic particle inspection ("Magna Flux") would be a good idea. Since you note the arm as hardened and having taken a bend, and since it sees impact loads, aside from years of service after being bent.... I'd want to check for any cracking in the arm. This will tell you if the arm is repairable or safe for continued use.
-If the arm is not cracked, if you want to repair it, do a hardness test on various parts of the arm. If you have not already done so, I would take a small round file and test an area of the arm for hardness. I would pick an area at an end, out of any bending stress. A small round file will be less likely to leave a stress riser. A similar test at the tip of one of the sector gear teeth should be done as well. The idea here is to determine whether the arm is hardened (or casehardened) over it's entirety.
-Have you spark tested the arm in some area that is not seeing any load and non-critical ? The spark test will tell you if the arm is steel, possibly which alloy, or whether it is a hugh-strength cast iron alloy. Harley had a habit of using some iron alloys for parts like footbrake pedal levers on some of their motorcycles. I found this out years ago when I was aksed to repair a foot brake lever on an old rat Sporty. The splines in the hub that engaged the shaft for the rear brake belcrank had wallowed out. The ear for the pinch bolt had also been distorted and wallowed out. The biker who owned the bike was convinced the thing only needed a welded repair. I looked at the surface finish and detail of the part and became convinced it was not forged steel. I spark tested, and saw sparks characteristic of cast iron. Seeing the deformation this part had sustained without cracking, I was fairly sure this part was some kind of ductile or malleable iron alloy. I was young and cocky, but not altogether crazy. I told the owner of the rat sporty I would not repair that brake pedal lever. He hunted up another rear pedal level. There was too much at stake with that part, and I was not going to be the one to take a chance on it.
I looked at a book I had with some photos of old Indian 4's. The only 4 pictured was a 1938 model. The kicker had a hub that was fixed to a shaft going into the tranny. It had a fairly husky rectangular cross section with rounded corners and an offset bent into it.
If that is the style of kicker, and you are set on straightening it, the "right way" would be:
1. Bead blast and do a non-destructive examination of the part before proceeding.
2. Take detailed measurements for what the arm must be to fit on the bike and work correctly. You might fabricate some sort of bending jig/gauge out of scrap steel.
3. Confirm the part as being steel, and spark test. Possibly have a hardness test done
(rockwell or scleroscope to get an idea of surface hardness). To obtain real certainty
about the part, the ideal (and impractical) approach would be to "section" a similar
kicker that is damaged beyond all repair, and do a "hardness traverse" accross the end
that has been cut. This would give you depth of case as well as hardness.
It is highly improbable you or anyone else would go to this length. The practical
alternative is to fall back on a spark test. If you see sparks characteristic of a lower
carbon content, you know you are likely dealing with some sort of surface hardening.
If you see sparks with a higher carbon content, you may well be dealing with a part
that was through-hardened and tempered to allow it to resist the impact loadings.
This determination is critical if you move to do any heating and straightening.
4. If the part is sound, make up a machined steel "dummy shaft" to fit in the hub snugly.
5. With the dummy shaft stub in place, anneal the arm so it is dead soft.
6. Using localized heating (brazing tip on a torch), straighten and tweak the arm as needed to bring it back to original geometry. This is where a bedning jig/gauge is helpful. I've built these out of scraps of channel steel and machined pins or dummy shafts to restablish angular orientation or centering on jobs I've had to straighten or repair weld.
7. Once the bending is done, anneal the part again.
8. Restore the hardening. Regardless of whether the part was an alloy that was through-hardened and tempered, vs case hardened, a heating and quenching is required. The type of sparks seen in the spark test will give a good idea if the steel is oil or water quenching. Spark tests give a general idea of alloying elements as well as approximate carbon content.
If surface hardening, a heating and quenching may be sufficient. If through-hardened, then you will need to draw the temper to get the right combination of hardness and shock resistance.
If you can find a commercial heat treating shop, they may be the best source for getting a handle on what the part is made of and how it is heat treated as well as hardness tests.
The final stop is the plater's.
Obviously, any of these approaches are involved. To get a commercial heat treat shop and a plater into the loop is going to be hard to find the right ones, as well as costly.
It comes back to how bad do you want that kicker to be "as per original design" vs. an "original" off a running old Indian.
I cannot resist throwing this one in: Cuban Hog and Indian owners have been making their own parts with great success ever since Castro took over. These mechanics are quite resourceful, and use anything they can get their hands on to make parts. They are legendary. With no alternatives, they have to be. If you can link up with the Cuban mechanics, you might get your kicker repaired or a new one made outright. Of course, you would then not have the original Indian markings forged into the part....
Joe Michaels
