Getting the right gear ratio for chainsaw bike?

Mrgoodcat

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Jul 29, 2021
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im having trouble getting the ratio right for my 42cc chainsaw bike im putin a jackshaft on and need to no my reduction ratio to achieve at least 45mph at 5-6000 rpm with max rpm @9000 how can i get it to work
 

Chainlube

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im having trouble getting the ratio right for my 42cc chainsaw bike im putin a jackshaft on and need to no my reduction ratio to achieve at least 45mph at 5-6000 rpm with max rpm @9000 how can i get it to work
Plug some numbers in here and see what you find.
 

Mrgoodcat

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Sidewinder Jerry

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im having trouble getting the ratio right for my 42cc chainsaw bike im putin a jackshaft on and need to no my reduction ratio to achieve at least 45mph at 5-6000 rpm with max rpm @9000 how can i get it to work
If the max rpm is at 9000 then max hp rpm is going to be around 7800 to 8200. So you should figure your max speed at 8000 rpm where max hp is. Realistically you probably aren't going be able to go beyond 35 mph with a 2 stroke 42cc engine.

At 8000 rpm on 27.5" tires you should use around an 18:1 reduction. 10:40 and 11:50.
 
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Mrgoodcat

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Jul 29, 2021
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If the max rpm is at 9000 then max hp rpm is going to be around 7800 to 8200. So you should figure your max speed at 8000 rpm where max hp is. Realistically you probably aren't going be able to go beyond 35 mph with a 2 stroke 42cc engine.

At 8000 rpm on 27.5" tires you should use around an 18:1 reduction. 10:40 and 11:50.
Ya I don't think I'm guna hit my mark i think I'm guna go with the Zeda 80 2stroke kit save me the headache and Damm near the same price all said and done by the time I put everything on this and it won't even do half of this other motor so... I got a little go-cart project on the go for my kids ill c if that lill 42cc will do them sum good thanx for ur advice I learned alot 🤟✌️
 
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