Crankshaft hardening

[max parsons]

Our local classic racer had his alternator side crank web machined to take a self energizing ignition system but it broke on the first outing.Was this because they didn't reharden the crank?If so can anyone tell us what steel the crank is made of and the best method of hardening it?

 

[Nessism]

What is a "self energizing ignition system" and why use such a thing? Lots of Suzuki GS engine race bikes over the years using more conventional ignitions that don't require machining the crank.

 

[jknappsax]

I think he might be referring to a magneto?

 

[GregT]

Our local classic racer had his alternator side crank web machined to take a self energizing ignition system but it broke on the first outing.Was this because they didn't reharden the crank?If so can anyone tell us what steel the crank is made of and the best method of hardening it?

Crank web - or the shaft machined ?
And what motor too please as this makes a big difference. The plain bearing cranks are forgings but the roller cranks are made up of individually hardened pieces....

If it's the shaft end machined to a different taper for example, I'd doubt if it's a hardening problem, more likely a poor job of blending into the existing shaft size.
What's the ignition ? What does the rotor weigh ?

 

[Rob S.]

I think he might be referring to a magneto?

Look anything like this?

 

[max parsons]

I don't know why he is using that ignition,maybe because he can afford it or maybe someone recommended it.It's a German brand.The bike is a 1980 GSX1100{see Stators Travel story}.

 

[GregT]

I don't know why he is using that ignition,maybe because he can afford it or maybe someone recommended it.It's a German brand.The bike is a 1980 GSX1100{see Stators Travel story}.

Probably a PVL. Good ignitions but expensive...small rotors too.

Hardening the shaft after machining would only make it more brittle. My best guess is that whoever machined it didn't appreciate the loadings and has taken too much off. If it's the type of crank with a bolt in the end retaining the rotor, the bolt should be as long as possible as it actually adds strength to the hollow shaft.

They're used a lot in the UK i believe - and in the IOM too - so someone there should know how to do it properly. Maybe Trident Engineering ?

As to why you'd use it which seems to be puzzling our US bretheren....it's a roadracing application. Long races on the IOM and no desire to either carry a battery or run a charging system.....QED