STUMPED ON THIS ONE

321 stihl chainsaw, i can not get any spark. have tried 5 new coils and two new flywheels an still cannot GET SPARK!!!!!!! any body have any ideas. all wires going to the switch are already unhook.

Check crank bearings for excessive wear/slop,bearings may be worn & crank shifting on compression stroke changeing flywheel/coil air gap.This is a common problem on low end consumer weed wackers & leaf blowers

What model saw do you have? Stihl have never made a 321 that I am aware of. Are you checking for spark with an inline spark tester or just laying spark plug on the block and hoping for the best?
Are you getting the correct flywheel and coil on it? And as Joe eluded to, do you have crank bearings out that are letting the crank move up and down and mess up the coil gap?

Check both ends of the crank and make sure the coils grounds are good.

How about the kill wire that shorts out the ignition coil when the run lever is in the OFF position. If it's damaged it may be in the shorted position all the time and be the source of your problem.

The wire will be a small diameter black insulated wire coming from the coil. The output is obvious in that it goes to the plug. The ground for the coil when functioning, is through the laminations to the engine chassis. The other wire is the one I'm talking about.

Mark

my mistake 361 sorry all other wires are not hooked up as far wires for switch. inline tester and the tester spark plug clip style also. crank feels real tight far as sideplay. as of this morning another coil still nothing!!!!!!!!!anyone got idea. merry christmas everyone

Check your grounds. If 5 different coil packs don't work, it's something other than the coils. If the crank has little to no play that should cross that off the list. Is the jug tight to the crankcase? Has someone done some hot rodding to it? Is there a ground wire off the coil pack that's not attached?

i agree with you it should be something else but
what,cranks tight,no other wire involved other
than the kill wires to switch. all i can tell is
the flywheel was in to far on crank as it had worn
off some of the fins on the head. That is why i
replaced the flywheel part just to be sure. but
still no spark,going walk away from it till after
holiday then maybe it might come to me what the
h!!! going on. merry christmas everybody

Okaye what about this. Set all the flywheels one on top of the other and while doing so line up the Woodruff key slots so that they are all exactly in line with the flywheels sitting exactly one on the other.

Now look at the position of the magnets embedded in the flywheel. Are they all in EXACTLY the same position? If not you have your smoking gun.

I have had an engine that wouldn't start because the Woodruff key was half sheared and that small change in timing was enough to change the timing on firing the plug where the engine wouldn't start. A new, non deformed Woodruff fixed it.

So with that in mind if the magnets aren't exactly in the same position I'd say that is your problem.

Why don't you put your original flywheel back on and see if it gets spark? That would solve that in a heartbeat.

Mark

What is your air gap?

If the fins on block are worn from flywheel rubbing on same the eng is telling you something that you choose to ignore or don't understand,you have excessive end play in crankshaft.

There's probably nothing wrong with ign system,the most probable cause of no spark is magnets on flywheel not in line with coil leg(s) on compression stroke,without looking up eng assembly drawings online if crank is tapered on flywheel end the only thing that will allow flywheel to go onto crank too far is an extremely worn crank taper or taper in flywheel as taper only allows flywheel to slide onto crank so far till tapers match,if crank is straight with no taper then you'll have a shoulder on crank that flywheel butts against when properly tight,any movement of flywheel after that is caused by worn/bad parts in eng possibly caused by worn/bad bearings or spun bearing(s)and block damaged/worn & needs replacement,SOMETHING has to hold crank in position besides rod & chain and thats not happening if flywheel rubbing on fins.

If you haven't done so already loosen/remove chain from saw to remove tension on crank then check for sloppy bearing(s) & excessive end play on crank allowing crank to move in/out of block & take it from there.

If you are using Champion plug. Throw it away. I had two bad right out of the box.

(quoted from post at 10:56:17 12/18/14) i agree with you it should be something else but
what,cranks tight,no other wire involved other
than the kill wires to switch. a[b:4919615ec1]ll i can tell is
the flywheel was in to far on crank as it had worn
off some of the fins on the head.[/b:4919615ec1] That is why i
replaced the flywheel part just to be sure. but
still no spark,going walk away from it till after
holiday then maybe it might come to me what the
h!!! going on. merry christmas everybody

Click to expand...

OH! Now you tell us the flywheel was grinding on the head. That's should have been among the first things to pass on to us! See Joes answer. You have crank bearing problems of some sort.

yea thats what i thought at first,already checked
the crank, bar and chain been off from start. i
built a tool to hold just the heads of chain saws
when i test run them. merry christmas

thats what i did when first pulled flywheel after seeing rub was check crank. bar and chain been off from start of work on unit.merry christmas ps yea i have seen the magnets out of line issues also so yea i know what you talk about.

If the flywheels are hitting the jug then the only things I can think of are either the crank bearings are bad, the bearings themselves have shifted on their seats (never been in a 361 so don't know how likely this is) or the flywheel end of the crank is screwed up. If more than one flywheel hit the jug it's got to be one of those. I could see one flywheel being mismachined or something, but not 2 or 3.

If someone else was inside the saw before you and did the old "take the flywheel off by smacking the crank nut with a hammer" deal they could have cracked the housing or shifted the bearings.