Forum

[Norm]

I need to replace the points cam on an SR2 mag and from what I see it looks like after removing the screw the cam should come off with a 2 jaw puller or is there a special puller for this? I would think it is only held on with a taper?

[Bullet Whisperer]

Hi Norm, yes it is just a taper with no key. It will come off in the manner you mention, sometimes you can get lucky and get them off using a pair of flat screwdrivers. Make sure you refit the cam correctly, so that you get maximum 'pull' from the armature just as the points start to open, or you will have no spark !
Regards, Paul.

[Norm]

Thanks Paul, problem is points on the left cylinder are opening earlier than the right side. I'm ordering a new cam and hopefully that will solve the problem

[Dennis C]

Hi Norm, A lot of them have this problem, changing the cam may not cure it, I did mine by carefully re-profiling the cam with a fine file on the one that opens earliest, finish off with fine wet and dry paper then solvol autosol for a final polish.

[Norm]

Thanks Dennis, I slept on that idea last night, the tedious part of that is fitting and testing,bit more with the file,fit and test,bit more with the file,fit.........

[Dennis C]

Hi norm. It's not difficult to do, just turn the mag to the point where the cam touches the heel on the one that opens soonest then turn 180 degrees and measure the gap, and that's how much you need to remove, hopefully a new cam will sort you out but it's not always the cam itself that causes the problem. As Paul says if you do remove the cam make sure you get the new one on in exactly the same position.

[John M]

I'm not sure, but as an aside I think the screw on the end of the shaft may be a left hand thread. In case you were not aware.

[Norm]

Hi Dennis, Paul, The only thing that I see about getting the cam back in exactly the same position is that the timing isn't messed with? It can go on the shaft in any position, only means you have to reset on the advancer? I can't see it causing any other problem. Thanks for the tips. Screw thread holding the cam on is right hand

[Bullet Whisperer]

Hi Norm, if it is an SR2, it will have a rotating magnet [armature] with the coil above it. If it is one of these it is vital that the cam opens the points at the maximum magnetic flux point of rotation, or you will be unlikely to get a decent [if any] spark. The SR magnetos can be set for reverse rotation just by moving the cam relative to the armature, but again, the points opening event has to coincide with the high point of the magnetic activity between the armature and the body. If you havent yet removed the cam, try and make a note of its' position relative to the armature, assuming the sparks were strong enough as it was.
Regards, Paul.

[Norm]

Thanks Paul, of course the coil is above, why didn't I think of that. Haven't removed the cam so I can mark it. Mag has just had $500 spent on it so spark is good. It would want to be, in the end it would have been better fitting a Pazon unit, fit and forget