As i've posted many times, i'm not a huge fan of HS40. Instead i like the HS50 on my 1970s minibikes, and just make the HS50 look like an HS40 ("the look conversion".) There's a variety of reasons i like the HS50 better. One, the HS50 is just more readily available. Two, it offers more horsepower (we're not 10 year kids any more!) Three, parts are easier to get. Really the only downside to the HS50 is "the look" (it always had the more squared top blower housing) and the flywheel (typically big and cast iron.)
To get around these two issues, I generally look for the HS50 in the "A", "B", or "C" models. That is the HS50 from 1972 to 1979. In 1980, starting with the "D" variation of the HS50, the flywheel taper was changed. So the crankshaft and the flywheel are a bit different. Luckily where i live (midwest) there's an abundance of 1970s snowblowers with the HS50 available for often pretty cheap. I tend to buy these up.
To get "the look" (that is the look of an 1970-1972 HS40), the blower housing needs to be the rounded top variety. These were used from 1968 to 1972 on the HS40, and actually other models too (H30 and H35, among others.) Again i buy these when i see them at minibike swap meets, they are generally fairly priced (and usually missing the serial number tag, which to me, is not important, and in fact beneficial, because the price is lower.)
blower housing comparison, square vs round: http://www.pinrepair.com/minibikes/p/snowblow62.jpg
Unfortunately you can't just bolt the slimmer rounded blower housing on an HS50. It won't fit, because the HS50 flywheel is thicker. A lot thicker. But with the HS50 models A/B/C you can use a 32517 alloy flywheel (the flywheel used on non-lighted HS40 engines prior to 1973.) It will fit right on the HS50 models A/B/C. And it gives a lot of benefits. Because the 32517 flywheel is lighter in weight than the cast iron monster (or even a 1972-1974 alloy HS50 flywheel), the engine will get to high RPM faster than a cast iron flywheel equipped engine. AND with the 32517 flywheel (and proper starter cup), the H30/H35/HS40 rounded blower housing will fit right on the HS50. This give the HS40 "look", with the added performance benefits! it's a huge win all around.
Cast iron HS50 flywheel vs the 32517 alloy flywheel: http://www.pinrepair.com/minibikes/p/snowblow63.jpg
But here's the dilemma... the 32517 flywheel is very elusive today. and generally pretty expensive. but there are other flywheels used on the H30/H35 that are abundant. for example #31332 (H35) and #1267 and #610781 and #610757 (H30.) These are alloy flywheels with magnet positions identical to the 32517 flywheel. Unfortunately, the taper used on the h30/h35 crankshaft is different than the HS40/HS50 crankshaft. So you can't just put one of these h30/h35 flywheel on an HS40 or HS50 engine.
With this in mind, i bought a 610757 alloy flywheel off ebay. Not an ideal flywheel, as it has teeth for an electric start, and it's for an h30 engine. But the core (the part that touches the crankshaft) is aluminum (the 32517 and 31332 have steel cores, which is ideal, more on that in a second.) I figured out the taper used on the HS40/HS50 pre-1980 flywheel, and cut this into the alloy 610757 flywheel. Also re-cut the keyway groove, and remove the outside starter ring teeth from the flywheel on the lathe.
So what did i end up with? a SUPER light weight alloy flywheel "on the cheap" that would fit an HS40/HS50 engine. This flywheel is featherweight, like nearly half the weight of the 32517 flywheel. Unfortunately it has an alloy core, which may not be ideal for longevity. But as an experiment, this flywheel was ideal. AND IT RAN. used an HS40 that i bought today at the minibike swap meet for $50 as the test engine (and set its original 32517 flywheel aside.) And the modified flywheel fired the hs40 engine without issue!
the 32517 vs the modified 610757 flywheel, mounted on an HS40: http://www.pinrepair.com/minibikes/p/tec_flywheelconvert1.jpg
with this in mind, i modified a 31332 flywheel in the same manner (these have a steel core, like the 32517.) And a 1267 flywheel too. so now i have a pile of allow flywheels i can used on the HS50 models A/B/C. Obviously i need to test more, but this looks like a good solution to the elusive 32517 flywheel problem.
The early 1970s HS40 engine with the modified alloy h30 flywheel: http://www.pinrepair.com/minibikes/p/tec_flywheelconvert2.jpg
Next up... modify the h30/h35 alloy flywheels to work on "D" and "E" model HS50 with the changed taper, This would be great to have more HS50 engines i can convert to an alloy flywheel and the rounded blower housing. Could also use that style of flywheel on the "F" and "G" HS50, but those are CDI, so would need a points/condenser magneto to do so. Probably can't go later than "G" model HS50's as there may not be mounts for a magneto on those blocks (not sure about that.) Note modifying the old h30/h35 alloy flywheel to fit on the newer taper 1980 and later HS50 crankshaft may not be possible, because of a lack of flywheel material. I will investigate this and give it a try though.
Comments or ideas?
To get around these two issues, I generally look for the HS50 in the "A", "B", or "C" models. That is the HS50 from 1972 to 1979. In 1980, starting with the "D" variation of the HS50, the flywheel taper was changed. So the crankshaft and the flywheel are a bit different. Luckily where i live (midwest) there's an abundance of 1970s snowblowers with the HS50 available for often pretty cheap. I tend to buy these up.
To get "the look" (that is the look of an 1970-1972 HS40), the blower housing needs to be the rounded top variety. These were used from 1968 to 1972 on the HS40, and actually other models too (H30 and H35, among others.) Again i buy these when i see them at minibike swap meets, they are generally fairly priced (and usually missing the serial number tag, which to me, is not important, and in fact beneficial, because the price is lower.)
blower housing comparison, square vs round: http://www.pinrepair.com/minibikes/p/snowblow62.jpg
Unfortunately you can't just bolt the slimmer rounded blower housing on an HS50. It won't fit, because the HS50 flywheel is thicker. A lot thicker. But with the HS50 models A/B/C you can use a 32517 alloy flywheel (the flywheel used on non-lighted HS40 engines prior to 1973.) It will fit right on the HS50 models A/B/C. And it gives a lot of benefits. Because the 32517 flywheel is lighter in weight than the cast iron monster (or even a 1972-1974 alloy HS50 flywheel), the engine will get to high RPM faster than a cast iron flywheel equipped engine. AND with the 32517 flywheel (and proper starter cup), the H30/H35/HS40 rounded blower housing will fit right on the HS50. This give the HS40 "look", with the added performance benefits! it's a huge win all around.
Cast iron HS50 flywheel vs the 32517 alloy flywheel: http://www.pinrepair.com/minibikes/p/snowblow63.jpg
But here's the dilemma... the 32517 flywheel is very elusive today. and generally pretty expensive. but there are other flywheels used on the H30/H35 that are abundant. for example #31332 (H35) and #1267 and #610781 and #610757 (H30.) These are alloy flywheels with magnet positions identical to the 32517 flywheel. Unfortunately, the taper used on the h30/h35 crankshaft is different than the HS40/HS50 crankshaft. So you can't just put one of these h30/h35 flywheel on an HS40 or HS50 engine.
With this in mind, i bought a 610757 alloy flywheel off ebay. Not an ideal flywheel, as it has teeth for an electric start, and it's for an h30 engine. But the core (the part that touches the crankshaft) is aluminum (the 32517 and 31332 have steel cores, which is ideal, more on that in a second.) I figured out the taper used on the HS40/HS50 pre-1980 flywheel, and cut this into the alloy 610757 flywheel. Also re-cut the keyway groove, and remove the outside starter ring teeth from the flywheel on the lathe.
So what did i end up with? a SUPER light weight alloy flywheel "on the cheap" that would fit an HS40/HS50 engine. This flywheel is featherweight, like nearly half the weight of the 32517 flywheel. Unfortunately it has an alloy core, which may not be ideal for longevity. But as an experiment, this flywheel was ideal. AND IT RAN. used an HS40 that i bought today at the minibike swap meet for $50 as the test engine (and set its original 32517 flywheel aside.) And the modified flywheel fired the hs40 engine without issue!
the 32517 vs the modified 610757 flywheel, mounted on an HS40: http://www.pinrepair.com/minibikes/p/tec_flywheelconvert1.jpg
with this in mind, i modified a 31332 flywheel in the same manner (these have a steel core, like the 32517.) And a 1267 flywheel too. so now i have a pile of allow flywheels i can used on the HS50 models A/B/C. Obviously i need to test more, but this looks like a good solution to the elusive 32517 flywheel problem.
The early 1970s HS40 engine with the modified alloy h30 flywheel: http://www.pinrepair.com/minibikes/p/tec_flywheelconvert2.jpg
Next up... modify the h30/h35 alloy flywheels to work on "D" and "E" model HS50 with the changed taper, This would be great to have more HS50 engines i can convert to an alloy flywheel and the rounded blower housing. Could also use that style of flywheel on the "F" and "G" HS50, but those are CDI, so would need a points/condenser magneto to do so. Probably can't go later than "G" model HS50's as there may not be mounts for a magneto on those blocks (not sure about that.) Note modifying the old h30/h35 alloy flywheel to fit on the newer taper 1980 and later HS50 crankshaft may not be possible, because of a lack of flywheel material. I will investigate this and give it a try though.
Comments or ideas?
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