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Big Bore Kit


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Oh, I see. You can get a +4 crank long rod for $500, then you'll need either a spacer plate or your head modded. If you have an aftermarket head, you'll need the right domes.

 

If you run standard pistons, I believe you need a 7mm plate. If you run wiseco 795 long rod series you will need a 2mm plate. Don't quote me.... my numbers may not be exact.

 

You'll need the correct porting to be done. According to Vito, you need to have the bottom of the tranfers lowered 2mm for the extra stroke to keep the stock timing. I'm not sure how well that would work. I can see the logic, but I'm leaving it to a pro.

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Why do you say the +4 stroker is a beter way to go??

I have a 420 b.b. and it goes prety good but I did a bunch of upgrdes all at once so I'm not sure what made the big difference. As always though it is not enough, so I was thinking of stoking but my porting guy says stroking doesn't make much difference and therefore is not worth it.

So why do you guys think it is??

What kind of power gains can you expect from a +4 stroker??

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The +4 stroker adds big punch down low and if you port it specifically for the +4 long rod crank it makes pretty much solid power from about 1800 rpm all the way through around 11K with a set of CPI's with no lag anywhere. Even without the big bore pistons you cant hit 80hp...big bore stroker?...gee..how much power do you need?...Jim

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The strokers may make better power down low, can't confirm or deny that. If you are looking for a good MX motor, try one of the powervalve top-ends. I went with the RZ as the "cheap" way out. If anyone wants to know the most expensive way to make 60ish HP, I'm your man. I have no complaints with the motor at all, makes great power down and let's you lug higher gears for less tire spin and shifting. Does anyone know how RZ's do with a little more stroke? And can previously ported(MX) cylinders be built to work with a +4? Always looking for "better" power. Thanks

 

 

 

broke

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