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Hr +3 Crank With Athena 12.5:1 Piston

911 Views 6 Replies 5 Participants Last post by  yfz450_0569
I read somewhere on here that a +3 crank would increase my compression .5... Is this true? This would make it a 13:1 then? What octane do I need to run then or what mixture of race fuel and pump gas? Also, what cubic inches will this be then? I sill haven't put it together but working on it.
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You'll atleast need to run mix fuel.
Its kind of tricky. I think you have to find out if the compression of your piston is based on the 04-05 crank or 06+ crank.
When I put mine together Diesel told me that the CP wicked was based on 04-05 so the 13.5 on an 06 crank was actually 13, but the extra of the +3 adds .5 compression so it was a 13.5:1
Its kind of confusing and probably doesn't make that big of a deal, but its something to check. Maybe terse can help you out a little more. He's good.
471cc, you could probably run a pump premium 94 and be fine. it would run ok. you should run it with a additive in it or mixed with 100 octane
Forgot to mention it's an Athena 98mm big bore with the +3 HR Crank
That's what I was thinking, just making sure.
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