OK, I have a 91 fxr with a 80in evo. Here is my question. I think the previous owner had the top end modified and I need to find the stock values in order to move forward in my build. I believe the heads may have been decked. Is their a stock head measurement that I can refer to? Also, What is the stock cylinder bore diameter? Thanks

 

Stoke bore is 3.498

Maybe some of the other guys have a better figure and don't quote me on this as I can't remember where I saw this figure and may have even dreamed it, but seems the combustion chamber is about 82cc.

I don't have spare set laying around but seems that when I measured at the spark plug side, from the bottom of the head bolt washer counterbore to the gasket surface, it's 1.25"

 

Jerry,

Sounds like you could usefully find yourself a workshop manual! If you are going to dig around in there you will find it a great help. Get a parts list as well.

 

Very good advice there....factory service manual is the best one to get & parts catalog.