Yesterday, Christmas Eve, I opened the top end of my 91 FXR Evo for the first time and surprise, Ho ho hooo, found a very nice set of heads hidden within. Here are the specs, intake 1.925" - exhaust 1.625" - reshaped combustion chamber that resembles twin cam heads - nice big open ports, smooth, very well done and they came with flat top pistons and a .062 head gasket. Now I was going to install a Woods w6 cam along with a backyard ported heads milled .050", 10:1 pistons, and .030 cometic head gasket. What I was looking for is more horsepower by adding compression , about 10.7 to 1, and a little flow but, the old heads are going to flow much better and should be around 9.8 to 1 with the new gasket. I can't use the new piston to bring the compression up any more than I have because of the odd shape of the combustion chamber of the older heads. What would you do? And Merry Christmas!!

 

Sounds like you already have a nice top-end set up. How did it run? If not already done, maybe go with roller rockers, a healthier cam and a new carb?

 

It ran well but I want a little more torque. I was hoping to get as close to 90 HP as I could. I'm running a Mikuni 42mm , Thunderheader and installing a Woods w6 now.

 

there's a couple builders in here that belong to the "80 inch / 100 hp" club; they're probably busy with Christmas stuff today. Perhaps they'll chime in shortly.

 

Before taking anything apart, what was the cranking pressure?

 

145 dry. Thanks guys

 

145 dry, The motor looks to have about 10k on it, clean and tight. Thanks guys.

 

Could they be Branch-O-Keefe heads?

 

Not sure, Their is no tags but they do have big stamped numbers in them one is a 53 and the other is a 119 and they are well done. Not a back yard garage deal, no roughness or unevenness in the ports at all. I was quite surprised. But I would think heads like this would really give me some torque.? The bike is fast, and a Harley mechanic friend of mine commented on it's power after taking a ride one day but, I want a little more out of it.

 

Branch heads, Screamin Beagles have the combustion chambers redesigned but the insignia is plastered on the side.

Branch mirror polishes the combustion chambers as a trademark and a pioneer back in the day, only drawback was the larger spark plug holes would crack into the valve seat, Screamin Beagles added the twin cam spark plug size to get more meat in that area. Wouldn't start carving around on the ports Jerry Branch knew what he was doing and you have a some history on top of that engine but the larger ports and valves my leave a smaller cube engine weak in the low and mid area but storm up high.

Pistons are still available for those Branch heads but a .030 head gasket may get you where you want with the flat tops .062 is a thick head gasket. Compression and a W6 may get those Branch heads through the low side but modern porters are getting great results out of stock heads in todays street engines so in everyday riding stock heads in the right porters hands are better but in a range of $600, I would put some numbers together to make the Branch's work with a W6H because I like the history of Evo's and Jerry Branch's work was pioneering.

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