I ordered a set of Tman 600sm cams to go with the 110 stage 5 kit I was going to order well I decided not to do the 110 kit since the new motors are right around the corner but now I have cams that like 10-10.5 compression closer to 10.1-10.2 but TR told me they would work good with 10.5 as well So I am just wanting now to throw some JE pistons in the bike and port the heads while leaving the valve sizes the same.

So as far as pistons go I have a quick question should I go with JE 10.5 or 10.0 compression pistons I was thinking the 10.5 with a .040 head gasket and that puts compression at 10.4 now with that I shouldn't have to worry about detonation should I? trying to order pistons tonight if I can get someone to answer it if no replies Ill just go with the 10.5s and go from there. haha

 

JE makes several 10.5 pistons; you really need to know dome volume so you can accurately calculate compression, more importantly corrected compression and CCP since static compression really doesn't tell you anything.

You should also be installing larger valves in the ported heads to take full advantage of the higher lift cam.

I run the 600SM cams with a set of JE flat top pistons in an all bore 107" motor at 10.4 static. Corrected compression is 9.4 and CCP is between 185-190psi. If I was doing it over, I would shoot for more compression, not much, maybe corrected at 9.6 and CCP about 195ish.

 

I was planning on going to 1.9 and 1.610 AV&V valves but I honestly can't justify it now that I'm only going to have the bike another year and a half and down the road if I do decide to keep it its not that big of a deal for me to rip the heads off and send them to the machince shop for bigger valves I know they say do it right the first time but if I were doing that Id go 110 with some Kirbys or Scotts head work and be done with it but I'm going cheap this time and staying 103 that way I can at least use my cams I have sitting here new in the box haha
I want to say the JE flattops are 10.0 compression if I remember correctly so I will go 10.5 and then I can go with a .040 HG and be static compression about 10.41 and corrected would be 9.63 CCP at 201.9 this is according to big boyz compression calculator

324729 is the JE part number of the piston I am thinking about getting

 

Decided to pull the trigger on a cometic kit with the .030 HG to make up for the piston sitting lower in the barrel and not at 0 deck height so that will make up for compression lose with it not sitting at the top of the deck if I decide to go to a .040 its only $35 and the .030 kit was $15 cheaper already so well start and go from there.

 

Can those heads accept that much lift (.600) with out machining?

 

TMan says the OEM springs will work but I would check for coil bind to be sure; factory tolerances are often found to be lacking.

 

I will check for coil bind, TR told me I wouldn't have a problem with the stock springs when I talked to him on the phone and ordered them. So we will see! I might have actually contacted the place to see about getting some 10.25:1 JE 107 pistons so we will see what they say back tomorrow! So I ended up holding off on the gasket kit too cause now Im waiting to see if they can get me the 107 pistons before I go with the high comp 103 10.5 pistons CCP would be about 204 on the 10.5s and would be 199 on the 10.25s

I dont know the CC of my heads but if I see everyone gets between 85 and 86 so if Im on the high side it drops my CCp so 201 on the 10.5 which makes me feel a little better about pinging but I always have good 93 around me so I guess I just worry to much since I had a buddy do a stage 3 and it was a ping monster which sucked

 

Ended up going with the 10.5 103 pistons hoping to get them in the bike this coming weekend and get the bike to the tuner next week sometime might get a tuner cable and try and tune it a little bit myself the tune couldn't be much different then the one that already in the bike with just a compression and cam swap yeah I will get it dyno tuned this winter if I get the cable so we'll see what I decide to do with that one.