HS50 crank question

copyman

Well-Known Member
#1
I ended up buying the HS50 I posted about in another thread. Model # 67207D, Serial # 3187B (Looks to be 1973 engine) Problem is it has a 1" dia shaft that is 3" long. Is it possible to to change the crank & sump cover to 3/4" dia 2-1/4" long like most minibike engines use? Also if it is possible to change crank will I be able to use same cam, flywheel, etc that is on engine now?

If not possible or too much has to be changed can a 3" shaft be used on a minibike? I did see 1" centrifugal clutches available and a member here said it was possible to use 1" shaft but the 3" length has me concerned with clutch cover fitting etc?

Any suggestions greatly appreciated.

Thanks
 
#2
Any good machine shop could modify that crank PTO end to your exact specifications. In addition, there are members on this forum who have the talent and equipment to do the same. Respectively, I'll preserve their privacy and let them come forth if they choose to.
Michael
 
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markus

Well-Known Member
#3
Journal size is the same on all hs50 bushing supported type crankshafts, so it’s just a matter of using the crankshaft with the pto size you want. Seals etc.. are the same as well. If it’s too long for your application just cut it shorter.
 

copyman

Well-Known Member
#4
Any good machine shop could modify that crank PTO end to your exact specifications. In addition, there are members on this forum who have the talent and equipment to do the same. Respectively, I'll preserve their privacy and let them come forth if they choose to.
Michael
Hi,

Thanks for the reply. It makes sense and easy enough to cut the shaft length but having machine shop making PTO dia 3/4" has be puzzled. I'm assuming a lathe would be used to narrow to 3/4" but how could they do that with the Key slot already cut into shaft? Wouldn't the cutting tool break when it hits the key slot while crank rotating on lathe?
 

Triley41395

Well-Known Member
#5
Hi,

Thanks for the reply. It makes sense and easy enough to cut the shaft length but having machine shop making PTO dia 3/4" has be puzzled. I'm assuming a lathe would be used to narrow to 3/4" but how could they do that with the Key slot already cut into shaft? Wouldn't the cutting tool break when it hits the key slot while crank rotating on lathe?
Not if they know what they are doing. I do interrupted cuts all the time. You will/might have to have the keyway recut.
 

copyman

Well-Known Member
#7
Thanks for all the replies. I found an HS50 crank with 3/4" PTO on ebay. So to be clear I can change just the crank and don't need to change anything else? Of course I will be putting new rings, oil seals, gaskets, etc while apart but just wanted to make sure.

Thanks again
 
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