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Discussion Starter · #1 ·
Running an 98” big bore kit on 2005 Fatboy. Headwork done By Big Boyz Heads. Ive been running an Andrews 37N with 10:1 pistons. Heads measured at 86cc. So I believe I’m running just under 10-1 with .030 head gasket. Stock bee hive springs and valve size. I also changed the front compensator sprocket to 23 tooth from stock 25. Bike has lots of torque but seems like I may have left some performance on the table with original cam choice.
I now looking at Woods TW555-R, Andrews 54N, or even Andrews 67N. The 67 has the biggest lift .570. Not sure if stock bee hive spring can handle the 67N. I’m running with adjustable push rods, and Fueling HP+ lifters. I wish I had done the 10.5-1 pistons Originally. Looks like the Woods 555 and Andrews 54 like the higher compression. 67 show 10 to 10.8 compression. What to do?
 

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Just curious what your head work involved? I don't recall the details but the 05 model heads were a one year only head. And they didn't perform well. We're down a few hp to the 04 and 06 heads. Most people don't realize that. Did you have larger valves installed? I "think" those heads had smaller valves. But my memory isn't what it used to be.
 

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An Andrews 37n and 67n have the exact same timing and duration, only difference is lift. Even with the Bigboyz porting, to get more flow in the upper rpms to get any benefit from the 67's higher lift (or any higher lift cam) you would need bigger valves and manifold. What exhaust do you run, that too will make a difference. How is it tuned? How is performance off? What did you expect? With the gear ratio change, your running in higher rpms the engine will need to breath, and then remember the B motors don't like high rpm's.
 

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Discussion Starter · #4 ·
Just curious what your head work involved? I don't recall the details but the 05 model heads were a one year only head. And they didn't perform well. We're down a few hp to the 04 and 06 heads. Most people don't realize that. Did you have larger valves installed? I "think" those heads had smaller valves. But my memory isn't what it used to be.
Big Boys Head work dod the heads. Bean there felt i didnt need bigger valves. He said the 05 heads with porting created more velocity and would get plenty of air/fuel into the cylinders.
 

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Discussion Starter · #5 ·
I just arrived back home from an Iron Butt ride. 1500 miles in under 36 hours. Bike ran great except at high rmp (highway speed 3600 rmp) my external crankcase beather was puking oil gunk out all over. Seems that may be a bigger issue at this time.
 

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I just arrived back home from an Iron Butt ride. 1500 miles in under 36 hours. Bike ran great except at high rmp (highway speed 3600 rmp) my external crankcase beather was puking oil gunk out all over. Seems that may be a bigger issue at this time.
Usually a sign of bad head breathers,,,excessive ring blow-by,,,, or bad oil pump scavenging.
 

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Discussion Starter · #8 ·
Fuel injection. Replaced umbrellas and borke in new rings correctly from what i know. I did install a 2012 new style oil pump and cam plate used off ebay. Im wondering if pump isn't scavagimg correctly. I plan on doing a leak down test at an indy shop when i get a chance. That should show if i have bad ring blow by. Im thinking of replacing the 37 Andrews cam with a woods 555 this winter so i can easily change oil pump at that time.
 

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First,, sorry I confused 57 and 67,, 57 is the same as a 37,,, 67 will come on at a higher RPM and require more compression and really need to breath. A leak-down would be a good call, bore-scope if available. Biggest culprit with oil pump is scoring do to not aligning properly when installing or excessive crank run-out, or trash in oil. The breathers, you should be able to pull air out but not blow back into the motor.
 
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