Thinking about doing heads on my 2012 103 with 254e cams ,fatcat screaming Eagle race tuner. Question is how much compression do I use ? My builder is recommending 10.4 to 1 is that too much? He is recommending keeping stock flat tops and getting the compression ratio by milling and a 30 thousandths head gasket

 

someone asked a very similar question last week.

milling is irreversible. I've been there.

did he also tell you that you can only use adjustable pushrods and that there may be slight differences in fit as the entire motor is now shorter ?

my 88 FXRP has factory milled .060" heads. this has caused a number of silly little problems over the years which a stock bike would not have...like intake leaks, carb mounting brackets which are all off by .060" which means hogging them out with a drill resulting in slop at the bolts and weaker braces, top motor mounts.... etc etc etc.

if you go this route you must tell every tech that the heads are milled, other wise they could spent your money chasing their tail.

changing pistons is alot easier...there are a million pistons out there offering all kinds of comp ratios and squish patterns to work with various headwork

HD milled the CHP FXRP heads as the costs of developing custom pistons was too high for the small number of cop bikes with the pursuit motor*- and the aftermarket was not yet servicing the market

mike

* cop bikes were often available with stock, low comp or high comp motor and cam options depending on duty- pursuit, parade/traffic or regular duty

 

All of that sounds like too much. Have you thought about just change the final drive pulleys?

 

Thats to much man, just do the cams, tuner and exhaust

I wouldnt mess with the heads and such, keep it simple and not only will your warranty still be good but you'll have a ton of miles of good riding

 

Telling every tech that the heads are milled won't be a problem these are the only people that work on my bike I already have adjustable pushrods what I want to know is 10.4 to 1 too much compression To be a reliable bike

 

No, that is just the static compression ratio. Should be fine if matched to the correct cam set.

As far as miling heads? If one keeps the milling LESS than say, oh.... .045, you should be good. I'm sending out a set of my own MVA heads for a .030 just like you.

Dude above, with that 060 mill job... I bet he DOES have fitment problems. AT 60, one would also wish to have the Throttle Body planed at a new angle.

Pistons have a cost to them. A flat top is a flat top. A WHOLE lotta pop ups can NOT be milled flat AND... they will be forged pistons at that. Nothing wrong with running cast flat tops, as they sure are quiet. A 030 'haircut' is OK, in my book. ANY decent head porter HAS to cut heads a little to even out the CCs in the chamber anyways.

If dude is decent at his craft, have him tell you how many CCs the heads are when done. In THAT way, you will always have a reference when moving forward.

Static compression doesn't mean much. RUNNING compression means EVERYTHING. This running/ Dynamic compression includes the cams and their timing and is HIGHLY important.

Those 254s have an intake close of I think... 43*. That is WAY later than the 34* the stock cams have. If you do NOT mill the heads and install a thinner gasket, the thing will be a DOG down low, and is the 'why' of dude wanting to mill your heads. He has this figured out.

Dynamic, just quickly playing around, on a stock bike is like 9.18 compression. That 254 wihout milling and thinner gasket will be like 8.8 compression.

I do NOT think 30 is correct, more like 20-25, but 30 would end up with 9.5 compression, which to ME, and only me, is too much. On a bagger, I like that 9.2 dynamic compression... so talk to dude and have him use the calculators, as I can NOT remember how many thousandths it takes per CC reduction. ANyways, you are on the correct path, IMHO.

 

My dealer has a screaming eagle kit comes with ported heads, thinner gasket, throttle body, and 204 cams (I guess all I need for the stage four because I already have intake, exhaust and tuner) parts and labor $2700 supposed to add about 25 horse and 10-12 torque from what they say. I'm still flip flopping on it because it's a freaking bagger, for cris'sake, it's never gonna be the fastest out there, and it runs damn good now.

 

Thanks for the replies

 

Quote:

se-254e cam Kit

this cam provides great low-end torque along with
good midrange. A good “all-around” cam, the Se-254e
is a good match for a Dyna, Softail or light touring bike - road King

®, Street Glide® or road Glide® Custom -

when the aggressive rider desires a little more top-end

horsepower. In a 0-60 sprint or 1/4 mile drag race, the
Se-254e-equipped model would pull ahead of an identical model with a Se-255 cam.

Everything I have read says the 254e cam is for stock compression.
The 259e cams do work well with added compression.

 

10-15 tq, is a WAY better riding bike IMHO. It will be a whole new ride. Everyone who comes on line and states there bike runs good, has NOT rode a bike with a decent tune, and has not road a slightly hotter bike. Good tune and more power transforms these bikes completely.

Not picking on you at all, dude, it's just my observation that all the members here tend to think their bike runs great. As compared to what? Is MY question. I HAVE compared things...