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440 big bore

1182 Views 1 Reply 2 Participants Last post by  SlammedRanger
I know its been a discussion many have had but i recently bought a 99 400ex with the 440 big bore. Ive heard there are many problems with the big bore and i purchased already built so not sure what all went into it. Its already having head gasket problems is it worth it to stay big bore or tear it down buy a new jug and start over.
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My personal opinion is ditch the 440. Go with a 416 or 426. What i would do in your case is buy a sleeve from LA sleeves and have it put in your jug with a 426 bore. Send the jug off to snure interlocking and have gt thunder hd studs installed. Buy an 88mm piston kit with cometic gaskets. Wiseco,JE,or CP. I would also suggest you jet it correctly. And add a few extra cooling mods. Shrouds,fan on oil cooler, bigger oil tank. Something in that area. And you will have a good running quad for a long time.
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