Stihl FS45 trimmer flywheel woodruf key

[billyboy]

Usually started fairly easily, then it wouldn't, seemed like the closest thing to starting was a backfire. well the the woodruf key in the fly wheel is sheared. Is there a fix other than getting another flywheel. These are the molded in place type key. Very nice design!!

 

[Chevboy0167]

I'm sure it could be repaired with some machining work and finding a woodruff key. That would probably take more time and money than just buying a used OEM.

https://www.ebay.com/itm/274953708411?hash=item400484a37b:g:LFQAAOSwbRNhR8Mu&LH_ItemCondition=4
https://www.ebay.com/itm/165156961337?hash=item26741f3c39:g:rN0AAOSwUl5hfLMP&LH_ItemCondition=4

 

[billyboy]

I did order a used one off ebay but i thought i saw a post about some guy filing a grove in the flywheel and jaming a wooden dowl in it. I agree trying to machine it would be spendy. Don't really want to take it all apart too many times either. Maybe the dam thing wasn't tight enough and it gave way. "Cheesey" best describes this key.

 

[frank_]

I did order a used one off ebay but i thought i saw a post about some guy filing a grove in the flywheel and jaming a wooden dowl in it. I agree trying to machine it would be spendy. Don't really want to take it all apart too many times either. Maybe the dam thing wasn't tight enough and it gave way. "Cheesey" best describes this key.

i needle filed a few, lightly fitted them, and drove a nail down the hole and cut the leftover nail off
mainly the mower ones that have an alloy shear key that avoids the crank bending if the blade hits a tree root or brick ,but also did a stihl sheared one

 

[billyboy]

@frank_ pics or video the next time you do that, would be interesting, thanks

 

[pioneerguy600]

There is an actuall broaching tool to make a keyway in a flywheel but a hacksaw blade wrapped on one end with a ball of taspe works very well and quite quickly.

 

[billyboy]

my dealer needed $90 for a flywheel but I got a used one coming for $14. Don't see how I can even stop to think about it for that kind of money. The hacksaw blade sounds good but I couldn't get my head around matching the divot in the shaft. Doesn't look big enough to hold more than a couple tears. Suppose a guy could make some sort of shaped form with wax. Last time I ran it was with plastic cutter blades and I try to avoid hard objects. Maybe I need to stick to line with it.

On another note, I have a FS90 and I would like to know if the valve cover is supposed to be air tight. Was going to adjust the valves and don't know if I should put new cork gasket in it or maybe some gasket sealer. Any help would be appreciated. Thanks

 

[pioneerguy600]

Since the keyway is only there to align the flywheel to the crankshaft for ignition purposes no key is actually required to hold the flywheel in place. The flywheel will stay where it is seated on the tapered crankshaft if tightened down properly. When I advance timing I often leave the key out of the equation, when swapping coils, modules and wiring in chips the timing for spark is often in need of adjustments. Once the proper timing is found then that is where I often cut a new keyway in a flywheel. In your case all you need to align the flywheel to the crank is a center punch, mark the flywheel, mark on the crank stub.

 

[billyboy]

Can someone tell me what the resistance should be on this coil? I get 294 on the primary and 2182 on the secondary. Is there a substitute for the 4140 1303A coil?
I have replaced flywheel and carb and still no joy.

 

[Chevboy0167]

billyboy, look here....

https://www.ebay.com/itm/3138344531...1fdb8b9:g:NrgAAOSwtKhh4jYD&LH_ItemCondition=3

 

[billyboy]

Thank you

 

[Chevboy0167]

Yeppers. To add, using a multimeter ohm test alone on an electronic coil will not work. There is a transistor and capacitor inside that coil that need energized and triggered to operate.

Now on an older saw with points and condenser, an ohm test works on the coil and the condenser.

 

[billyboy]

I have a good blueish spark with the ground opened pretty wide on the plug and all I get is a what seems like a backfire. The legs of the ignition module are over the magnets at TDC. Don't know what else to do but try a coil.

 

[frank_]

I have a good blueish spark with the ground opened pretty wide on the plug and all I get is a what seems like a backfire. The legs of the ignition module are over the magnets at TDC. Don't know what else to do but try a coil.

i usually check the timing with a strobe, to avoid it being a moneypit
also i had one last year that would cough but not run, but ran ok with the muffler removed (was blocked)

 

[billyboy]

I had the muffler off and flames shooting out 2 inches or more. Very low use on this machine. Pristine P&C. Got it out last spring and wouldn’t run. Took it to a Stihl dealer. He thought it was flywheel. Don’t have a timing light. Sparks very good with plug grounded on cylinder and with inline spark tester. Floods easy if choked too much.

 

[billyboy]

@chevyboy0167, Are you sure the 1305 will substitute for the1303A. One of the listings I found on eBay said it wouldn’t. Thanks

 

[Chevboy0167]

Sorry Billy, I can not confirm it will. Was just what I found on the bay with a quick search. Somebody with Stihl IPL access could maybe confirm?

 

[billyboy]

Oky dockie, found a used 1303A with a bit more searching, Thanks

 

[billyboy]

Update here, I got a used coil off ebay and it started with a couple cranks. Put the old carb back on and it ran on it too. All that mucking around and all it needed was a coil. Dang. It would have been so easy just replacing the coil first. Oh well, $40 in new and used parts and it lives. And I have a new spare carb sitting here for it.

 

[Rein]

Update here, I got a used coil off ebay and it started with a couple cranks. Put the old carb back on and it ran on it too. All that mucking around and all it needed was a coil. Dang. It would have been so easy just replacing the coil first. Oh well, $40 in new and used parts and it lives. And I have a new spare carb sitting here for it.

So how is it running with what you described as a sheared key? Did you just align the flywheel with the crank slot and tighten it down?