H35 "upgrade"

capguncowboy

capguncowboy

Well-Known Member
#2
#2
I have a late 70s HS50 taking up space in the shop. I haven't cracked it open yet to see how it looks inside, but I suspect it wasn't used much
 
delray

delray

Well-Known Member
#4
#4
davidcmay said:
Hello All,

I am having a bit of a hard time finding a good engine for a build. I have a couple of early and late 35's in need of machine work and was wondering if they can be bored out to make a HS40 or 50?


https://www.oldminibikes.com/forum/tecumseh/128117-h35-vs-hs40-whats.html

I have zero dollars invested in them and having machine work done is about $65.00

Thank you in advance for your suggestions.

Dave
Click to expand...

when you say want a good motor for a build? what kind of build are you talking about? something without the governor on and more then 4hp or with the governor on with a bigger piston . for example a hs-40 piston in a h35?
 
delray

delray

Well-Known Member
#7
#7
davidcmay said:
Yes, an 40 piston in a 35


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Click to expand...
ok david, I am going to assume you want to make it a built engine. there is going to be a lot of if's here. so the first thing your going to have to do is some measurements and research make it happen. you did mention you had some early motor and a late model 3.5hp motor(late model you want). if you have the correct motor it will use the same connecting rod as the hs-40/50 use. so now you can use a billet rod. big plus!
next you would have to look at the bore. now if I am correct your motor will have a 2.500 ? and the piston you want to go with will have a 2.625 bore. that would be a .125 over. first thing you will need to look at is your bore and see if the casting is large enough to take on that larger piston and if the head gasket will work with a big bore or have to be modified it or use the a hs-40 gasket...etc.. and if the head it self will work on top of the big piston and if it's anything like a hs-50 to a hs-40 they both use different head gaskets. good thing if it did work your compression would go up little. if you got this far? you could still run the stock cam with a better spring, hot coil,good carb...etc... and make that little motor spin 4500 rpm's all day.
 
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delray

delray

Well-Known Member
#9
#9
ok cool, I do plan on looking into this also this winter if time permits. I got other projects that need done first. see how it go's.

I would recommend a newer style hs-40 piston that uses the thinner style rings. first see if you can get pass the if's …….:thumbsup:
 
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