Topic: What's the trick to disassembling the advancer?

[Jore]

I'm in the middle of installing a tytronic ignition on my bike, a 75 400, but I need to remove the cam from the advancer and replace it with a part supplied in the kit, thing is, I already removed the circlips that hold the weights down and also the springs, but beyond that I can't take out the arms or the cam, how are you supposed to do that, the only thing that comes to my mind is bendig the tabs on the side of the unit so I get clearance from the arms, but that doesn't seem right.

Help please!

[madmtnmotors]

the only thing that comes to my mind is bendig the tabs on the side of the unit so I get clearance from the arms

Nooooo! Don't bend anything. It's a little bit tricky, but all you have to do is rotate (advance) the points cam and as the weights swing out there is a spot where the arms on the weights will slip through the notches on the cam allowing the cam to be lifted off. The weights do not need to be removed, but you might remove them to clean and lubricate the pivots while your in there. Keep track of all the little washers too. 

[madmtnmotors]

Clarification:
    I see you are working on a 400. The method I described is for a CB750 since I do not have any hands on experience with a 400 I do not know if they are the same.

[BomberMann650]

Should be like madmtn says.  The 550 is the same way.  Gently twist and pull.

[Jore]

Is that all there is to it?

I've been twisting this thing for a while and only get some binding, but the guy in the video just pulls it out like nothing.

[BomberMann650]

Might be dirty inside.  Heat and Lubricate.

[Jore]

It spins freely, but i'll give it a go

[strynboen]

mine just fall apart....both the 400 and the 550..

[Jore]

I'm soaking mine in acetone for the moment, i'll try it again in a while.

[Jore]

I found a second advancer I have, but that one's jammed up, it's also soaking in acetone for the moment.

[Jore]

Not sure if it's visible or not, but I think I found the culprit on why the advancer can't be taken apart


I few years ago, when I first got the bike I tried turning the motor with the big nut on the points side, i promptly snapped the 2 nubs on top of it, so I got the part rebuilt in a machine shop, iirc they welded new nobs to it and then machined them down to the approximate size, the advancer opens and closes freely, but once I try to remove the center cam it just binds, turns out there's this tiny lip right where the stamped mark is, so I'm guessing that's what's preventing from coming out, for now I can only think of taking it to the machine shop and turning down that edge so I can install the new part on it.

[BomberMann650]

Just use a file

[754]

 A file is your friend.. if its weld it might be very hard, if a file just skates across it, try emery cloth on a ruler or other flat surface.

[Jore]

Coouldn't take the darn thing apart, not even my machinist buddy could, so we ended up cutting the cam away with the lathe.