Looking for a couple hs40 model numbers so I can try to locate a crank.

125ccCrazy

Active Member
#1
I have an hs40 engine I'm gathering parts for to rebuild for a member here and his crank is shot, The shroud on this engine may not be the correct one and the part number that comes up for this model is NLA, his is the extended shaft for a TC but he told me a shorter crank will work for his bike..I need model numbers for a HS40 points engine with a bearing crank.

Any help will be greatly appreciated.
 

markus

Well-Known Member
#3
hs40 BB standard length crankshafts:

32716 (three revisions so can try adding a, b, and c ), 32891 32716 is the earliest version and has a slightly different taper on the connecting rod journal and should be used with an early rod if you do actually find one that not a-c.
 
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125ccCrazy

Active Member
#4
hs40 BB standard length crankshafts:

32716 (three revisions so can try adding a, b, and c ), 32891 32716 is the earliest version and has a slightly different taper on the connecting rod journal and should be used with an early rod if you do actually find one that not a-c.
Mark,

are those part numbers for the extended cranks or standard length?
 

markus

Well-Known Member
#5
std length, the extended bb crank is 33080, I dont have any engine numbers for std length BB engines onhand but you can tell by the sidecover and dia of the crankshaft/seal area if your hunting engines. Need to be 1979 or older to have the same small taper.
 

markus

Well-Known Member
#7
yes, actually a fair amount of the 70's bikes were just using std shafts to power the bolt on TC bikes. My JCP Digger (made by Bird) the factory engine was a std shaft bushing mated to a cat 99 TC stock, that was slanted app 1973. Same went with a 1970 K-C dura bike I recently had, comet bolt on TC on std shaft lighted HS40.

An interesting thing I noticed in one of my books with an April 1980 revision is if you needed a replacement hs40 block that was ball bearing, the only thing available was the longshaft 33080 and the books states to change out that shaft for for the shorter shaft dependent on application. You would think that would mean there was some pretty good stock of those but that was 36 years ago.

Edit: I figured out the changeover point where Tecumseh simplified all the small frame engines to one larger taper and larger flywheel nut 10-1-1980. Engines built before that date even if they have square shroud and steel flywheel will still be usable with the pre 1974 aluminum flywheels and curved shrouds typical with the most popular years of vintage mini bikes. same applies to most H35 and smaller as well as the HS50, so if you are looking for donor parts engines to repair your earlier engines keep it in the 70's

That means these are the last engines before the change:

 
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