Not on the 56mm cylinders, pretty much all I did with them 2 year's ago is clean up the ports and add a finger/bridge x-sectional area addition to the transfers towards the intake side and simple muffler mods. Trying to get their R's up a little. I guess that intake horn I got last year is a mod. To be honest those 56mm's are hard enough to pull over as it is. Even though I thoroughly understand the importance of compression & squish relative to efficiency....a man has to know his limitations. My 56mm "bling saw" is at .034 squish so it wouldn't be hard to take another .010 and wouldn't add enough to the free port to matter. "Bling" saw has turned out to be both useful and fun, even though its not "optimal" so I'm going to just run it for a while as is. On the 54's thats another story, as a few have come with .050+ squish and I have put them on the lathe to get them in the mid .020's . BIG difference BTW definitely worth doing along with a clean up & adjusting of the ports. An obvious difference. The good news is unlike the Husqvarna's, you can take a LOT off the base w/o making it too thin. I really try to get the blow down numbers in the 18-19 degree range as now the floor of the transfers drop well below the piston crown at TDC. A low blow down (higher transfer) seems to help offset that along with a steeper angle on the top of those transfers. And also I've kept the exhaust in the 99-100 degrees ATDC even after dropping the cylinder & have the blow down in the 18-19 range. Seems to work pretty well. BUT there are folks here who can give far better advice & better numbers I'm sure, all I can do is report what I've done to this point in time. Also while Brad or Randy do that stuff on a regular basis, its a bit of a PITA for me to go that far & I always question my work, especially when the 56mm's slightly tweaked run as strong as they do. Another "opinion" is I don't like cutting the Huztl squish bands with the plating "spots" with my boring bar. So worked around that either by just shooting for a good squish number to the existing squish band and one I tried a popup. Haven't finished putting that last cylinder on anything yet, have a "Cross" top end that "bumped" it. But plan to have a "timed" comparison of the Cross as delivered vs. a cleaned up 54mm Farmertec vs. a cleaned up 56mm Hyway Top End when I get the time. Have two of the three "comparison" saws built, the Cross MMWS 54mm and HTSS tweaked Hyway 56mm.
