Well, if the HD dealer tech told you all that, it must be true. Not trying to start some chit but just a friendly suggestion that I have seen this dealer build/customer movie before and the ending always turns out the same. Customer spends a bucket of money but the build doesn't meet expectations. Or, the customers new 103" SE build get smoked by a 95"er and wonders why.

Not saying that is your situation; don't know you or your dealer but, like I said, have seen it all before. I tried to attach the 103 stage kits from the SE catalog but the file is too big. The Stage II, III and IV kits are the same from my '09, '10 and '11 catalogs. I still think you have a discnnect on the head/piston combination. You mentioned that the heads were cleaned up, mirror polished exhaust ports, polished the combustion chambers and swirl finished the intake ports. One would expect that the chamber volume would have been checked and balanced. Ask your head guy if that was done and what was the chamber volume.

You won't be able to do a compression check by hand; you need the starter to spin and the throttle held wide open. I have said my piece and that's all I can do. Good luck with your build and I hope it meets your expectations. At the end of the day, that's what matters.

 

Please don't get me wrong I really appreciate the info from you fellas, I just wouldn't think the motor co. would put out a kit that is that bad and if ya think the engine is gona be a dog with 255's it must really be weak with the 253's because I'm sure the 255's picked up the cylinder psi. alittle. There is another fella on here that did the same kit last winter and he ran the kit's 253's and said the bike runs strong. He did post pictures of his assembly and he too has flat top cast pistons, I'll try and look him up and see if he has numbers from his tuner.

 

It's not that I Want to run flat tops, They are what came in my SE103 kit and again my paper work states 9 to 1 compression with the 253 cam's. Just sayin that's all and with today's Gas that they have for us to run I'm worried about knockin and such. I don't want to be to high in compression and have to add octane additives to my tank.

 

Sounds like your working on a heck of a Science project. I'd shoot over to a CVO forum and see what those folks have been running in the old CVO 103's.

 

Good suggestion. Dyno data will tell the tale.

The 255 is a great torque cam but it does require some compression to make power. I just helped a buddy with a Stage III 103" build; dealer winter special, kit at half price was too hard for him to pass up. 109TQ/95HP with stock heads, .030" head gasket, SE255 cams, stock head pipe with Rush slipons. 100TQ from 2600rpm to 4900 rpms; not bad for a dealer package. The difference between his and yours is static CR, his is 10.1. Chamber volume on his stock heads was 85.5ccs; I believe your chambers will measure 98cc which lowers the CR with flat top pistons. Still think you have a mis match between pistons and heads but JMHO.

 

as i stated before in a previous post every thing is their... running compression will be below 9-1 103+ heads are ment to be run with domed pistons... if nothing else at least deck the heads to a specific compression 10-1 static maybe a runing compression of 9.8-1 with your cylinder presure around 180 or so

 

OK so what I'm getting from the guys { Thank you to all ! } is that my cranking psi should be around 180 or more inorder for this engine to make any power. What would be the upper limit compression wise before I start having trouble with knock and ping on premium pump gas ? putting in a set of forged high compression pistons is not that big of a deal with the engine on the stand. the hard part is spining it over fast enough to check the clyinder pressure first because if it's around 180 or a little more now I should be ok right ? I do want to check it first.

 

im at 195, and on 91 oct. and i rattle on a HOT day. most of rest of the time OK.

 

You will get varying opinions on this but on a touring bike I have no problem with 10:1 static as long as corrected is about 9.3-9.4 and cranking between 180-190psi, with compression releases. The problem you have with the mis match between heads and pistons is that as it stands now, with a .030" head gasket, static is about 9:1, corrected about 8.7 and cranking 178psi. So, while cranking is up because of the early intake close of the 255, your corrected CR is still low. You could shave the heads a bit but you will just push cranking OTT to achieve a better static/corrected CR.

Best bet is stock heads at 86-88cc or a set of dome pistons with a +/-8cc dome. That get's static up to about 9.8, corrected at 9.4 and cranking just south of 200.

Your build will run and run better than the 88" you had before but it won't run as good as ti could with the current configuration. I have to tell you that with the $$ you have invested in this build, I would consider putting the heads and cams on Ebay and going with a set of ported stockers and a TMan or Woods 555 cams or one of the higher lift Andrews grinds. Much easier to tune and better performance. JMHO.

 

i say runn a diff cam like the woods 400. cam choice will be left to you and your builder cause every one will want you to use a specific cam...

i run 10.94-1 with acorrected at 9.9-1 my cylinder pressure is at 207.7 psi. my heads are decked to 92cc's. a street motor set up to 10.5-1 with a corrected at around 9.8 or even a little lower you would be fine.. a 1550 with stock heads and flatops will run a point higher then stock stock compression is around 9.2-1 the extra bore goes to 9.35.1 with a .030 hg and a running compression of 8.68-1 and thats with a ss 510 with a stock cam its at 8.88-1.

but your running a set of heads were the intake valve is over 2 inches. were the exhaust is over 1.5 inches. your gonna need more then 9-1 compression to make power... if you wanna use that cam thats fine but no matter wich way you slice this equation your gonna need more compresion then them pistons will give you.. them heads decked to 92cc chambers for instance with flat tops will be at 9.53-1 with your 255 cam and a +4 advance gear your at 9.31-1 and 193.6psi running compression. wich in my opinion would be a great running motor and would haul nice...