Why do points ignitions need adjusting?

[Nath]

Simple question, what actually is the reason that the contact breaker gaps and timing need adjusting on a bike with points ignition?

Okay, so something is getting worn, but what? The cam? The "cam follower" half of the point(s)? The actual contacts themselves?


The timing is at its furthest adjustment on my bike for one pair of cylinders, can I just lengthen the adjustment groove/slot with a file to create more adjustment?
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Hard livin', hard luck.

[stinkwheel]

The electrodes wear away, the spring loses its spring and the backing plate moves. The first is probably the most significant in your situation, the electrodes are just worn away from clattering into one another 5,000 times a minute.

Points are a disposable service item. If you run out of adjustment, it is time to replace them. They cost a tenner per set from David Silvers.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[tonyyzf]

The cam does wear, thats the reason you used to get a little packet of grease with every new set of points

[finpos]

get a new set!

what's actually worn away is the wee bit of whatever it is that contacts against the spinning shaft. And if that's worn down to a nub, then the electrode contacts and the spring will be in a right state.

finpos.

[tatters]

You can buy a electronic conversion kit for a lot of bikes, my dad got one for his 1967 BSA A65 (CDI and pick up plate thing) for £60, was well worth the money and makes the bike a lot easyer to start.
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Past:NRG50,AF1125(x2),NSR125RR,ZZR250,CX500,VFR400,KR1S,ZZR600(x2),CB400N,YZF1000(x2),KH125,Z200,FX400R,CBR954RR(x2)GPZ500S,GT550,VFR750F(x2),RD350N,XR650R,CBR600F,CB250,KDX250,YZF750R,CRM250,400EXC,KLR650,TTR600RE,DR350S,R100GSPD,RGV250,VMAX1200,DL650,KZ750 Present:G650XC,C12,CRF450X,1190ADV

[Nath]

I think I'll go for a new set of points then. I've avoided spending money on this bike so far, but I guess there's some things that you shouldn't scrimp on, and I am planning to do some serious mileage on the bike.

I'm not really fussed about getting an electronic ignition. They are well over £100 for this bike (CB550), and I like the idea of mechanical components where you can actually tell if something is wrong and do something about it. Apart from some slightly dodgy fueling, the engine runs very well and nearly always starts first kick.
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Hard livin', hard luck.

[ZRX61]