Need some Magneto information

Well guys, the time has come and I'm tired of my electronic ignition mod. It's too much work to keep the battery charged, and the power is all over the place day-in and day-out. (The timing seems to wander around somehow).

I am considering going back to a battery-less setup, with a magneto, as best I can. I need to ask a question about magnetos though:

My husky came with the SEM ignition and had the lighting coil for the headlight and red tail light. HOW is timing changed on that setup, assuming I still had it on there? Am I correct for assuming you would just loosen the 3 screws that hold the stator to the engine housing and turn it one way or the other for advance or retard?

Also, Does the placement of the flywheel/magnet have to be anything special, that is, can you just stick it on or does it have markings on it that must be matched to TDC? (or actually, a 3-way match: Stator vs. flywheel vs. tdc). The other reason I ask this, is because while looking at SEM flywheels, there is no crankshaft alignment key like there is on others like the Motoplat systems.

well,
basicly..
you set the piston at TDC, i like to set them at the start of the peak.
and you will find on a Motoplat. a small hole in the flywheel, that mates with another hole in the stator, all of those should line up,
yes, you can move the stator base and the stator itself with 3 screws on the stator, and 3 on the plate, to fine tune so to speak.
the SEM,s that i delt with were set up the same way.
this is for a 2 cycle..4 cycle is a different story.

Awesome, that sounds pretty easy! This is a 2-stroke so this is the info I was looking for Im psyched about the idea of merely lining the holes up, and all is well.

Whats the best way to find TDC? Would you use an endplay dial or what? Also, would you happen to know, or be able to hazard a guess on what gap clearance between stator edge and inner edge of the flywheel is? Thanks again!

on the forum. youll find a post with some downloads for shop manuals for the vintage Huskys, you may want to download one.

Thanks, I found the general owners manual thing as well as the service bulletins that tell you ign timing and oil capacity and what not...Those are worth their weight in gold (when they're printed on paper, not on the internet haha).

I was wondering why the ignition timing between Motoplat and SEM is different. It says 17 degrees advance on Motoplat and 20 degrees advance for the SEM setup. I thought that was odd. It didnt tell me about rotor-flywheel clearance though. I guess as long as they dont hit they're fine.

I'm still not clear on what method I should use to find piston TDC -and- how accurate my TDC reference needs to be. As in, I could use a drinking straw down the plug hole that will raise up when the piston comes up. However, with that being such a rough method, would that still be enough error that I could cover up by pivoting the rotor one way or the other??

you can use a dial gage like shown in the manual if it make you feel better.
what works for me, is a long screw driver.
down the hole. and by hand turn the flywheel, with one hand, and hold the screwdriver handle with the other, you will feel the point were TDC is reached, then a flat spot, then the piston starts back down.
what i do..is just as the piston reaches TDC, before the arc of the downside return, thats were i set my timing marks.
that might be a redneck way of doing it, but for 30 some odd years of working on Huskys, its always worked well.
as for your flywheel to stator clearance??why worry about that? nothing you can do to adjust or move that. once the stator plate, and stator are screwed onto the case, the flywheel slips over the crank shaft and it sets that no matter what you want.
short of milling or grinding, you cant adjust that gap anyway.
make sure your key is in good shape.
you may want to lap the flywheel on to the crankshaft, before you set this up.
those neet little manuals you have will show you how to do this.
if your buying a used SEM or Motoplat, make sure you get the stator and flywheel as a set, dont buy a stator then a flywheel.. no matter how good a deal they look like..
they are a matched set.. anytime iv sold stator, its been with the flywheel, and upper coil, all off one bike...
and have yet to have one come back, or problems with them down the road.
one thing you may want to do...is when your letting the big sit for a few months, remove the flywheel cover so it can stay dry, being closed in that cover tends to let things crust up, and get nasty..a little air is a good thing.
after i wash a bike, i remove the cover, blow out the flywheel with air, and spray some WD40 lightly. so water doesnt build up.

Great info! As for worrying about clearance between the two, I kinda do need to know. Reason being I dont have a threaded end OR a tapered part on my crank- It busted and the end that was left was smoothed out. It is drilled and tapped in the end for a bolt which is why this is a hardcore project. I'm not to the point of buying the ignition rotor & flywheel yet, since first I have to figure out what I need to do to have that crank ready to accept a flywheel. (short of buying an engine, or splitting this one to put a crank in). Im not sure if a machine shop can help me or anything like that.

Anyways, Thanks for the idea of a screwdriver down the plug hole. If it worked for you, thats what I'm going with. I dont even have a dial gauge but if I absolutely needed one, I could borrow one Im sure.

Here's a picture, not a great angle or quality, of pretty much what I currently have. I have since cut the crank trigger metal piece into a point to make me feel better. You'll see I dont have much crank to work with.

http://img34.imageshack.us/img34/4994/triggere.jpg

wow,
belive it or not, i busted a crank snout like that one time.
tried and tried to make it work...
a new crank would be your best bet... heck you can get a used crank or even a used bottom end pretty cheap.
whats the year and size?

I believe it's an 82 or 83 model 250cc. Being in my 20's I dont have much cash to drop on this stuff. I could PROBABLY snag a used engine; Ive seen them on ebay for around 300, but they have no ignition so I would have to drop some additional $ for that, and I'm not looking to put that much into the thing if I can really help it.

some big changes from 82 to 83..silver or white frame.? air or water cooled?
single or twin shock??
vin number and Engine number would help..
i may have a good Engine that would work...complete with electrics.

Its definitely got the white frame. It's a hodge podge it seems. The decals said 250 XC, it had the lighting coil, head and tail light, but different fenders from what ive seen. Also has the yellow seat where most that ive seen are blue or black. It's air cooled, dual ohlins in the back. I dont have the serial # handy, but could get them to you.

sounds like an 83 or 84..

not sure were you located at, but right now, theres a 84 250 WR on Fleabay as a parts bike in MI..looks like a good start for a builder engine.

Im in Alabama, so I'm sure shipping would kill me on that LOL. Im gonna see if I can mess with this some more. I'm not dumping any $ in to it, so it cant hurt to screw around with it I guess.