I have an 09 flhx 96" with true duals, 551ez start cams and SEPRT. I'm looking at doing se 103 cylinders and SE cnc ported heads. Will I run into any issues with the 10:1 flat top Pistons or is that to much compression? I know that's at the high end according to the S&S website. Any advise from you guys with experience with the 551's would be appreciated!!

 

9.8-1 and have your heads done in a toring version

 

Have you thought about the new drop in 110" cylinders and pistons?

 

I second that Q

 

Not interested in the 110 and spending the extra $. Was just looking for a simple dependable budget build. Just worried about how the increased compression and 551's will work together.

 

Well then, it appears Kirby has answered your questions and at 10:1, you have a compression problem. Suggest you familiarize yourself with the BigBoyz or a similar compression calculator. BTW, noting complicated or not dependable about the 110" drop in cylinder/piston kit, so perish the thought. If it's budget, that's another matter but if you want to play, you gots to pay. Good luck!

 

Kirby,
Looking at the bigboyz compression calculator. It looks like static compression is 9.87:1 and corrected compression is 9.69:1 without knowing deck height. Is this acceptable with a good tune?

 

Kirby is probably busy working; just because he is a forum sponsor doesn't mean he sits in front of a computer screen 24/7 waiting to answer questions. If you really want a reply from Kirby, you might want to give him a call. Since he is a forum sponsor and does this stuff for a living, when you address a question to Kirby, or Scott for that matter, you are pretty much telling other forum members that you don't want to hear from them. Most forum members don't want to jump in when a question has been directed to a forum sponsor.

So, you can wait for Kirby or perhaps put your question to the forum. Just a friendly suggestion.

 

Kirby always gives a nice straightforward answer without a big sales pitch, just like he did here. You might just ask him to furnish you a cam, bore your seasoned cylinders to pistons and then port your heads to match. That way you get something that you know will work right together.

AMS in dallas does a nice and economical 105" package with heads setup for touring bikes.

 

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It would be nice if you gave us the cam specs on your cams so we dont have to look that up.

But 10.0 comp or higher may or may not be an issue with detonation (esp on hot days) and proper cam selection is key because too little duration & overlap with result it too high cyl pressure leading to detonation but choosing a cam to run with 10-10.5 comp thats got the right amount of duration/overlap LSA etc it key esp on today lower octane 93 fuel with 10% ethenol.

This isnt 1970 with Sunoco 100-102 octane leaded fuel avail at the pump!/LOL!!!

Some states do allow Sunoco unleaded 100 octane fuel to be sold at the pump ,but unfortunately for me not in NY where i live.

Tip,when you get this build done if it does happen to detonate on hot days on 93 pump fuel
(excessive engine heat can increase it's octane requirement) try this that reduced oil temp 50+ deg
(also reduced engine temp @ same time too) which can stop detonation on hot days due to significantly
reducing oil/engine temp .

I reduced oil temp 50+ on hot days (made huge improvement in the engines/bikes perf on hot days) when i installed Wards twin cooling fans along with an ultracool oil cooler also having twin cooling fans at the same time that working collectively together reduced oil temp 50+ deg f resulting in many positive results 1 of which was stopping detonation thats a reall issue with stock HD's that have very mild cam timing with low duration along with little to no over lap too resulting in higher cyl pressure even on stock motors like 96" with 9.2 compression.

Could run " real lead octane booster " (same lead used ti increase octane in fuel 40yrs ago) that can get pricey and can cause issues with 02's & EFI.

Heres a link to the real lead booster if you would like to check it out.

I have been using it for many yrs with great results classic muscle car motors i work on & or maintain for other people inc my own 1969 chevelle SS396 with big block chevy 4spd i bought from the original owner in 1978.

http://www.wildbillscorvette.com/OctaneSupreme01.htm

scott