I know the Bonneville pretty well, but I'm a totally amateur when it comes to these performance kits. Can someone give me a primer as to what's involved with upgrading to the
904cc vs. the 944cc vs. the
988cc kits? Keep in mind that I have no garage so this is all going to be handed to a shop to do.
You mean 994cc, not 944cc.
Both the 904cc and the 994cc kits are just big bore kits. The 904cc kit is just a bored out stock cylinder and the 994cc kit is a completely new billet cylinder. The stock cylinder can't be bored out to 994cc because it isn't thick enough. The 994cc also requires splitting the cases and boring them out.
The 989cc stroker motors are bored out to 904cc then stroked (I believe 4 or 6mm) to attain the 989cc displacement. The 1087cc motors are bored out to 994cc then stroked to achieve the 1087cc. These are the biggest, baddest, and most expensive mofos.
The easiest and cheapest to do is the 904cc, obviously.
If you really feel like making a strong Bonnie, I think the way to do it is to build it to 994cc and do the cams/carbs/headwork/etc. I would like to do that one day, when funds allow. A healthy 994cc engine with cams/carbs/headwork engine will set you back about the price of a nice used Bonnie, so for the price of 2 used Bonnies you can have a faster used Bonnie. Not practical, but fun.