95 fxstc. Got a base gasket leak, and I think since I'll have it apart, I'll bump compression with some new pistons. I plan on taking the jugs to a shop to true up the bores, and freshen up the heads.

Question 1: what's the difference between keith black and wiesco pistons, other than price? what compression ratio works best with the ev27 cam?

Question 2: should I take the heads assembled to the machine shop, or disassembled? What should I have them do? I don't want them to sell me something I don't need.

 

Most kb pistons are hyperutectic, where as the wiseco pistons are forged, they're are pros and cons to each, I personally run wisecos, I set them up a little loose and they last, with that said, I wouldn't go over 9.5 to 1 with the 27, you'll hear guys say all day u can get away with 10 to 1, but that's pushing todays fuel, also I would take the heads to the shop assembled, so there's no chance of mixing up valves and or springs. Good luck on the build . Chad

 

I just sent my heads and cylinders in for a rebuild last week so I have some fresh info here.

1.Difference in pistons is builder preference, both are great companies. I went with KB because that is what Kirby Apathy who is working my heads/cylinders suggested. I also will be running the ev27 when the parts get back.
2. send the heads assembled. You will want to get a valve job done while there out -- consider a port job. If...you decide to go with Kirby Apathy at Vee Twin he or his team does a SERDI valve job with new valves and a port and polish for 349.00 he will also bore cylinders +.020 or +.030 for $95 and provide gaskets to ensure the proper compression. They will mail (you pay postage at around 50 bucks) everything ready to install.

I have heard nothing but GREAT things about Bigboyz and Hillside. But Kirby was the only one who called me and explained everything to me.

Call each of these shops and pick their brains about what you are trying to do. you also may want to check out this thread.

https://www.hdforums.com/forum/evo-c...cylinders.html

[url="http://www.bigboyzcycles.com/[/url][/URL]
[URL="http://www.veetwinperformance.com/servmenu.cfm"]
[url="http://www.hillsidecycle.com/index.php/machine-shop/"[/url]

Lt

 

+1 on sending the heads out whole. I don't know if you you will need new springs and valve seals, but I did that on mine. I think you need a tool or a press to install the valve seals anyway.

I have Wiseco, and they are 9.75 to 1 with the ev27 cam. So far so good.

also +1 on Hillside. I sent everything up there and had it done it about 10 days. I contacted them a couple times while putting things together and Scottie was real helpful. I know next to nothing about wrenching so this was a process for me.

Only thing that didn't work for me out of that box was the S&S chrome pushrods. they had to come out. Andrews quickee style went in, and all is well now.

 

For the machine work I have Larry mcbrides shop (cycle specialist) right around the corner. Two other machine shops, and 4 indys say take your stuff there. Must do something right. I'll wait and see if anyone has wanything bad to say. Ill also have to check his lead times, 10 days shipped is awesome.

 

install viton seals in the heads...for sure

 

Next time I go in mine, I'll be adding the "Haden oil fix" and possibly "slobber stoppers".. Cam, pistons and headwork are a must for an Evo that is being torn apart. As long as you dont go crazy, you'll never regret it. I run the SE11(similar to the 27) in mine with 9.5:1 Wiesco's and a "street port" of the heads.. I'm very proud of it, runs great and reliable, its very responsive and plenty of power.. Night and day difference from my other Evo's.. As a disclaimer, I'm not an Evo expert, so, some of the guys here may add a different perspective. But,while I believe the heads do need some massaging, I wouldnt go nuts on them for a street bike. You could easily run the price up if you get carried away, but it may not be bennificial at the lower RPM's you normally drive at. As a rule, going too large on the valves will kill low end power. With the simple "street port" the shop did on mine, their flow numbers are better than the new Edelbrock's he just flowed. They did install slightly larger valves, springs and seals as well as clearance them for .580" lift. While I only have a .508" lift, I wont need to worry about the heads if I decide to change my cam in the future.. Just a bit of forethought if youre going to spend the money, just do it once..

 

You are right, even with stock valves an Evo head needs very little work to put a smile on your dial....I always advocate for mild tuning to preserve the rideability and "Harleyness" of the power delivery....75-80HP is just right on a 1340.

 

What's the average hp increase with bumping compression to 9.5-1? Also, exactly what should I tell the machine shop to do to the heads on a 40k mile evo? I'm not trying to break the bank, only want reliability. Valve job only?

 

Multi angle valve job will do, port reshaping usually includes making the ports smaller rather than bigger. 9.5 - 1, an EV46 and 10:1 with a valve job will give 75HP.

An EV27 and 9.5-1 plus valve job should give 70HP, depending on other things like pipes and air cleaner.