Husqvarna 50 flywheel two keyways

[macadoodle]

So I’m refurbishing a husky 50. I dismantled and installed a new piston and cylinder. I removed the flywheel and didn’t notice that two keyways are cut into the flywheel and only one key on the crankshaft and now don’t know which one is correct.

Anyone know which one is correct?

Thanks!

 

[frank_]

is there a number stamped near the keyways ?

 

[cscltd]

With the distance between the two. It shouldn’t be hard. loose install on one and see were piston is at tdc in relation magnets over coil lamination
one will be so far out on timing It should be noticeable

 

[NSEric]

If you look really closely at the flywheel, one of the keyways holes should be dirty or a little rusty from not having anything in it, while the other will be shiny and clean from removing the keyway.

 

[macadoodle]

is there a number stamped near the keyways ?

Couldn’t find any numbers, and both look remarkably similar so using the dirty/worn or not method didn’t help me much. cscltd, makes sense, one position will line up close to TDC and the other will be way off. I’ll give that a shot.

Thanks for the input folks!

 

[ballisticdoughnut]

Look at the outward facing side of the flywheel. If there’s two keyways there should be some kind of identifying mark for both.

 

[82F100SWB]

Just looked at the one from the 50 I have in pieces, the position marked 5 was in use on mine

 

[Huskvarna hotellgäst]

Should be a "4" next to one of the keyways. This is for Husqvarna 40,45 & Partner 400,450 with Electrolux ignition, due to the module being mounted above the flywheel on the cylinder rather than on the crankcase. (40/400s with Phelon ignition use a different flywheel.)
So.. the other one is the one to use on 50,51,etc.

 

[82F100SWB]

Related, but not really, any idea why the closed port saws(5000/490, 590 and 325/5500) have a different part number crank than the open port saws? I'm guessing maybe the keyway is located differently? I havent had reason to dig too deep into my 590 and check yet.

 

[Huskvarna hotellgäst]

Related, but not really, any idea why the closed port saws(5000/490, 590 and 325/5500) have a different part number crank than the open port saws? I'm guessing maybe the keyway is located differently? I havent had reason to dig too deep into my 590 and check yet.

The numbers may change and the specification improve but the cranks were fully interchangeable back in the late 1980s when these IPLs were printed.
In this case 5031121-01.

 

[82F100SWB]

Looks like the 400 used the same crank as the closed port saws. I know when I was looking at the same year IPL's the open port and closed port saws ran a different number, check the same year 500, or 50 and you should see what I mean.

 

[Huskvarna hotellgäst]

I don't have any IPLs later than 1988 because that's the last year I oversaw production in Australia. We built thousands of Husqvarna 50, 40 & 45 as well as thousands of Partner 5000Plus, 500 & 400. In each case, when we pressed a crankshaft into the case halves of a 50, 5000Plus or 500, or onto the crankshaft of a 40, 45 or 400, we picked it up out of the same container.
When a spare crankshaft was ordered as a spare part for any of the aforementioned models, regardless of the part number specified by the dealer, the crankshaft they were shipped had the latest part number on it.
Also, I personally built 2 Husqvarna 50s with a 5000Plus cylinder and piston. Each functioned perfectly. We had no reason to suspect that they wouldn't.

What happened after 1988 I can't speak about but as the stroke for the 55 and 5500 is the same as on the 40 & 50 and 400 & 500 (32mm), the little-end bearing has the same part number as all the previously mentioned models (501 45 16-01) and the main bearings also have the same part number (738 22 02-25) and they all used the same flywheel and ignition module, I'm more than reasonably confident that the crankshaft commonality continued.