6.5 gear ratio question

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Ats3196

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Just installed 6.5 predator .. Can barley hit 20mph with governor removed .. Questioning gear ratio. I'm a total newb at this. It has 4 sprockets currently . And 10" slicks ... Any help appreciated !
 

Ats3196

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Not best picture but all I have at moment .
 

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Ats3196

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Will have to get sprocket sizes when I get home. My question is it seems like everyone else has two sprockets and one chain, while I have 2 chains and 4 sprockets ...
 

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ezcome-ezgo

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You have what is called a jackshaft. Sometimes it is necessary to achieve the preferred gearing. Once you have all the sprocket sizes, we can walk you through determining your existing overall gear ratio. If it is not ideal for your use/weight/etc., swapping out a sprocket on a jackshaft is usually fairly straightforward.
 

Poboy kartman

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You have a jackshaft...that's a good thing. Just count those sprocket teeth: engine to other side of that chain....other side of that shaft and then the axle. And measure the height of those rear tires.

EDIT: We posted at the same time...and DOH! 10" Slicks....
 

Ats3196

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From engine to rear shaft is 12 to 26
Then from rear shaft to wheel is 12 to 60
 

Poboy kartman

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From engine to rear shaft is 12 to 26
Then from rear shaft to wheel is 12 to 60

Yeah...there's your problem for sure...someone correct me if I'm wrong....but that's in the neighborhood of 9:1. The P.O. probably geared it that low because he wanted to slow it down for a young kid to drive.

Now, you have two choices: change the 26 to 12 or eliminate the jackshaft. (The jackshaft could make gearing changes in the future easier.)

Do one of those and you'll be going MUCH faster!
 

ezcome-ezgo

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If you buy a 10 tooth clutch, you can bypass the jackshaft. If you can't find a 10 tooth clutch, change the 26 tooth sprocket for a 14 or 15 tooth. I think? Someone double check me.
 

ezcome-ezgo

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A 14 T gives you 1:5.835, a 16 T gives you 1:6.665. So yeah, 13 or 14 is probably the best bet. I was splitting the difference to try to hit 1:6.

I am humbled by the PoBoy's vast knowledge and expertise.
 

Poboy kartman

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15 tooth would get you closest to 6:1 So there, nyah nyah.

No....do the math again....13 will... 15 would be 6.25 : 1...and with that light of a kart...he could almost..(and might be able to go 5:1)....so...nah nah yoself.:lolgoku:

EDIT: I gave up...and went to a calculator...I was correct on the 6.25:1, but missed on the 13... the 14 would be about 5.88:1....perfect...IMHO....But I stand corrected.
 

Ats3196

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Thanks for all the replies guys! I had only just bypassed the governor at first. But I just removed the whole thing internally. Going to bring a swivel from work tomorrow to get oil sensor out without having to remove clutch out of way.. Gonna order parts I need tonight. So from what I've read, 12 to 14. Then 12 to 60? So only swapping out the 26 tooth sprocket ? Also is rejetting carb worth it or difficult ? Thanks !
 

Ats3196

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Cool on the sensor. Thought it'd be another part that'll come loose eventually. I'm gonna post pics of my gear and ones I'm finding and see if you guys can point me in the right direction !
 
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