deciding to get head work done on mt 80in EVO motor with 85in big bore kit. I know many porters have different methods for doing heads. my question is this, is getting heads done by someone who uses a CNC machine the best ? as for quality , cost etc ??

 

I would like to know the consensus on this if there is one.

 

Torque plates. They don't use them, you don't use them (the shop).

 

Don't waste your money on the 85inch big bore, it's little more than max oversize stock bore...Evo's are 83 inch from the factory...now 2 inches may matter in bed but it don't matter on an Evo....


As far as how or what with head work.....use someone who actually knows how to port an Evo, it doesn't matter if they use a file and a chisel or a plasma cutter, if they don't know what to do it won't work no matter how professional the job looks.


A lot of people recommend Hillside Cycles but others may chime in with more advice.

 

I actually talked with Scott from Hillside yesterday. great conversation and info, was just curious what others thought if CNC gave better results or using a proven porter like Scott.

The Big bore kit was actually put in last year. I believe that was the biggest I could go without splitting the cases or going with a bigger bore ?? I may be incorrect someone correct me if im wrong

 

CNC will only give as good results as the design put into it. It is only a means of cutting metal, not designing and perfecting a port profile, so don't be concerned with how the metal is cut, only the reputation of the shop doing the work.

Hillside does a lot of work on a wide range of Harley engines. It would take a lot of effort to program a CNC machine to set it up for just one profile of ports, then multiply for every configuration. I suspect Hillside will discuss what you want of your build, recommend a suitable cam, then port your heads to match it. They probably have several port profiles for your heads, depending on cam, CR etc. Someone who uses a CNC machine won't have that flexibility, so is less likely to give you great results, compared with Hillside.

There - I worked that out as I typed it! Go with Scott.

 

As Spanners said, the 85" kits are simply max rebore size. Unlike the twincams there isn't the flexibility of bore sizes available for our Evos and stroking is historically the way to increase cubes. I had my original engine stroked to 89" - or 90" as I boasted, as it was rebored +.020 at the same time!

 

Don't waste you time with CNC'ed heads. Send your heads to Scott, I have a set of his Stage 2 on my 107 Twin Cam and a set of Stage 2 for my Evo. There's no CNC machine that can do the kind of work Scott does.