Misc: Ignition Magneto Points

[Pushrod Twin]

How does one ascertain whether the magneto points are tungsten or platinum?
My KVFTT makes a great spark, engine starts easily, then after some 500-700 miles, progressively starts to misfire under load. Inspection reveals a growth on one contact & matching divot on the other as material transfers. A quick rasp with a points file to remove the growth, and all is sweetness & light again for another 5-700 miles.
I suspect tungsten points, but I am open to all suggestions????

 

[bmetcalf]

I think that the platinum are approximately half the diameter of the tungsten.

 

[greg brillus]

The platinum points are definitely smaller in diameter......... From your description it sounds like the condenser is gone causing excessive arcing across the points. The platinum points are better but hard to find now.

 

[Martyn Goodwin]

decent replacement points in either material are becoming unobtanium.

 

[Pushrod Twin]

The platinum points are definitely smaller in diameter......... From your description it sounds like the condenser is gone causing excessive arcing across the points. The platinum points are better but hard to find now.

Thanks Greg, I considered that the condenser may be tired, but it does not exhibit the other symptoms that I would expect, hard starting or stopping when hot.

 

[Pushrod Twin]

Inspection of all my other mag's, KVF off my 48B & K2F off my G9, then comparison with the KVFTT indicates that the TT at least has the correct, small diameter, Platinum points. It also indicates that they are ready for another rasp and getting towards the end of their life.
So that brings us back to Greg's suggestion, capacitor requires replacement.

 

[Pushrod Twin]

decent replacement points in either material are becoming unobtanium.

Thank you Martyn, are there any solutions? They appear to be "brazed" or silver soldered onto the base one side,screw adjuster the other. Someone must have the technology to replace them?
What is the alloy detail of the platinum, should I ask a jeweler?
Does anyone have the detail for the tungsten alloy? As a machinist I am aware that tungsten comes in many grades, I have cut soft tungsten with a hacksaw blade & turned it with a high speed steel tool,which appears to be a contradiction when we use tungsten tools to cut hard steel. It was weights for propeller blade balancing. At the other end of the scale, tungsten carbide tools are hard enough to cut 60 Rc gudgeon pins. What is used for contact breaker points?
Neither points material appear to be "hard," a points file cuts them adequately.

 

[greg brillus]

Is it possible they soften with too much heat........arcing across them. The primary runs pretty much at around 200 volts at normal running speeds.....

 

[Trickymicky]

Dave Lindsley has replacement Platinum contact sets, although they are quite costly.

BTH 4BA PLATINUM CONTACT SET
LUCAS K2F/KVF PLATINUM CONTACT SET
BOSCH 3.5mm PLATINUM CONTACT SET

Prices are in his online catalogue.

I was led to believe that using abrasive means to clean platinum points is not a good idea.

 

[Bill Thomas]

After all these years, It is understood that a Lucas mag is not the best ?, It was NOT built for a V Twin.
For me the "D" Distributor is the way to go, Even The Vincent Factory thought that in the end.