Discussion in 'FXR Models' started by Scardhard, Jun 29, 2011.
Just how far can I bore out my stock jugs safely before I have to consider getting new ones??
Almost all major piston manufacturers make a .040" (3.538"bore) oversize for Evo's. That's as far as I would go.
Does anybody over bore then sleeve the jug back down or have I been working around diesels too long...lol...Carl
As far as I know, no one makes sleeves for an evo. Complete 3-5/8 cylinders are available from the aftermarket from S&S, Axtell, & maybe Rev Tech. But, you have to take the engine out and bore out the cases so they fit. If you look at some of the larger displacement EVO type engines over 96 cu. in. they are purpose built cases with stronger deck sections cast in to take the higher loading imposed by the larger jugs. Also, as in the case of Rev Tech their engines use thicker cyl. studs and have a different pattern. The pattern is one of the drawbacks to an EVO and is the reason the Twin Cam was introduced. There wasn't enough meat left in the deck between the stud thread holes and the bores for the cyl jugs. The 96 inch EVOs were stock bore and a longer stroke which means if you take the engine apart, you should bore and stroke it for the same price (approx) then if you did just one of the two. Look to spend around 4 grand for the machine work and an extra 1500 if some one assembles it for you. This assumes you do the heads at the same time to complement the other work. Get prices from different shops as the economy may work in your favor.
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