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What type of steel for a motorcycle kickstart lever?

What type of steel for a motorcycle kickstart lever?

What type of steel for a motorcycle kickstart lever?

I am in the process of manufacturing a kickstart level for a 750cc motorcycle.

The question is what kind of steel and process to use to make it strong and tough enough?

It is quite a complicated shape so it would be useful to cast it rather than forge it but I have assumed a casting would not be strong enough. Is this true or would a casting work with the right steel and heat treatment?

If it was forged (probably by hand) it could be made in one piece or the level section forged and the foot peice and clamp welded on afterwards. Welding would be another factor in the choice of steel and heat treatment.

The kickstart lever must be strong enough to stand the full weight of the rider about 12 inches away from the kickstart shaft without bending or breaking. The kickstart lever must be chrome plated without affecting its strength.

Looking at some of the application information the following two steel types looked interesting but I would be making an educated guess.

Nickel-chromium Steel Specification No. 3330. -- is intended for very important structural parts. The high nickel and chromium contents make it exceedingly tough and strong when treated heat treatment appropriately

Chromium-vanadium Steels Specification No. 6140. -- This is a very good quality of steel for use where a high degree of strength is desired in conjunction with considerable toughness. Its fatigue-resisting qualities are very high, and it is a first-class material for high-duty shafts.

RE: What type of steel for a motorcycle kickstart lever?

First, a good steel casting can easily take this nkind of load.  It's not usually practical to cast a single item, so I'd either hand-forge it or weld it up.

I'd also make it from 17-4 or 17-7 PH stainless. You could polish it when it's made and eliminate the Cr plating.

Just have it solution annealed after you forge or weld it, and then harden it for 2 hr. at 950 deg F min.  It will be strong yet will bend before it breaks-highly unlikely if you make it as thick as the orig., etc.

RE: What type of steel for a motorcycle kickstart lever?

Yeah, I got put in my place a while back for assuming that castings are weak.  I refer you to a thread that, quite coincidentally, is also about motorcycles:


RE: What type of steel for a motorcycle kickstart lever?

Yeah we jumped on you rhodie!

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