RGS KF2 Mag

[sprint]

Some advice please.

I have a RGS which I purchased last year. The Mag had been fully overhauled, have documentary evidence of the work that had been done.

I checked the ign timing when I got it and with the mag in the fully advanced position, sack cable, the the ign timing was spot on at 13/32" BTDC.

However, on a recent check I noticed that the cam seemed sticky in the housing when the cable was fully released the cam did not fully return to a natural stop and with cable slack you could still rotate the cam slightly by manual pressure?

I disconnected the cable and manually lifted and lowered the cam arm which showed that the cam was fairly stiff in the housing. I put a few drops of oil in the cam hole and after a few more lifts to and fro on the cam arm it freed and cam moved easily in the housing. However, I now found that because the cam was now able to rotate further when the cable was slack the ignition timing has now changed, looks like the cam was sticking and not fully returning and the ign timing looks to have been originally set in this position?

Which leads me to my question (eventually) what is the natural stopping position for the cam in the fully advanced position? There does not seem to be any physical stop so how do you know where the cam should rest/stop in the fully advanced position, cable slack?

Hope this makes sense to somebody?

A second question.

The quoted ign timing, 13/32", was originally for the std engine with 9:1 compression ratio. I currently have 8.25:1 so would I be better off with the std SRM recommended setting of 5/16" BTDC?

[trevinoz]

There is a stop. Have a look at the cam ring and you will see a notch in the perimeter which will hit the stop which is screwed into the bottom of the magneto end.
Make sure that the plunger which operates the cam is free and lubricated also.
You will probably find that 13/32" advance will cause pinging, even with your pistons, I know that mine pinged with the same compression ratio.

Trev.

[sprint]

There is a stop. Have a look at the cam ring and you will see a notch in the perimeter which will hit the stop which is screwed into the bottom of the magneto end.
Make sure that the plunger which operates the cam is free and lubricated also.
You will probably find that 13/32" advance will cause pinging, even with your pistons, I know that mine pinged with the same compression ratio.

Trev.

Thanks Trev

Have not worked on a mag before as my other bikes are unit Triumphs all now with electronic ignition.

Yes I see what you mean, at the back of the cam ring there is a cut out that limits the movement with a stop. At least now the cam rotates freely but a pain to have to remove the timing cover to set the ign timing.

Does the cam ring just pull out from the front and is there any problem getting it aligned/connected to the plunger again?

Andy

[trevinoz]

Hi Andy,
                     The cam ring just pulls out. Usually no problems getting it back in.
When I time an engine I have to go through the exercise several times as I usually have to "modify" the ring to get exact firing on both sides.

Trev.