I am currently in the process of tearing my 88" twin cam powered 2004 Fatboy apart and looking to spend some bucks upgrading her power plant over this Michigan winter ahead. Looking for some advice. I currently have added supertrapp mean mother's II staggered drag pipes on her and the screaming eagle pro tuner and it has been mapped and runs great. Although i am nearing 40k on the bike I'm really nearing the time for cam tensioner replacement and I've decided to go wiwits gear drive setup. Just not sure which one? I'm aware with the stock valves and springs I can only achieve .511" of lift and this displeased me. So I found a local guy that will port the heads and jazz them up. Now the question comes down to will I be able to get away with just a head job and bigger cams with gear drives or will I have to add compression also? I'm switching to a power commander and I will have access to a dyno to 're tune the efi. What else would I have to do to make this thing wake up? If I'm doing all that to the top end should I big bore it also? I really don't want to do a big bore if I don't have to. Any suggestions appreciated. Thanks. -nathan

 

The guy porting your heads should also be matching that to a set of cams. Plenty of builders here should chime in.

 

Yeah i was thinking the .583 ss gear drive kit. My biggest question is will I be able to flow enough air with my stock lower end or would it be wise to change the cylinders and pistons to up my compression. Or maybe just put in high compression pistons ? That's where I get hung up. I already have heavy duty clutch and primary.

 

Nathan, I agree with Soft, that your heads man should be able to recommend a 'package' of cams with pistons plus ported heads which will all work together. There are very experienced engine builders in here who could have done all that for you and they may chip in with advice. IMHO it is worth considering using S&S easy start cams, especially if you raise CR in any way. The only one who can say if your heads will flow enough for those 583 cams is your heads man! I have a 585 in my 107" Evo and a 583 sounds a bit ambitious.

 

An ago-old combo that works VERY well in many bikes, for many folks is this simple;
Bore to 98"
Andrews 37's (or now the 57's) 9.8-10.0 cr.
A set of our Stage I or Stage II Heads.
Big broad torque, cool running, and good fuel economy.
Just an example.....
Scott

 

What am I looking at as far cost on a set of stage ii heads?

 

I am feeling very ambitious haha. Michigan winters are longgggg and boringggg. Have to look forward to something.

 

Looks like I'll start with having the heads done and see what he recommends, what do y'all pay for a head job? Just curious. This guy says he can port them bench flow them and put my bike on a dyno for 650$

 

If he is going to port/flow check and install those, plus tune it for that type of money............that is a deal God didn't give Noah.....
Scott