[bishop]

OK tuners.... I'm getting ready to build a new drag motor for next years ice racing and wanted some opinions. It will be a 800cc triple. Polaris' xcr 800 is 72 x 65. I was thinking of changing this to 69.5 x 71. Any opinions on that?? Most of the engines that I see are pretty much the same with the exhaust port about 70%, pretty square, opening at about 80 ATDC give or take. These engines have big transfer ports that open at about 112 ATDC or so. I usually deck the case to put them around 115. Because the ports are so large would I benefit by getting them even lower?? They are angled up at about 10-15 degrees and I usually cut these more flat. The secondaries have big hooks keeping the stream seperate from the boost stream. If I stoke it, I will sleeve the cylinders with a aluminum sleeve with no ports in it so I can put them wherever I want. I can pull the aux exhaust ports back to get them wider than 70% but I should probably make the radius' larger. Which is better narrower and square or wider and more oval shaped?? If I go stroker, the sleeve will have to protrude out of the cylinder about 200 thou or so but I guess that would be OK. RPM.... I had a sled that made 208hp at 9600 and then I changed the pipes and got it to 227 at 10300 but it was slower on the track. Maybe due to the CVT?? I was even thinking of trying a pipe with narrow band high peak down around 8800 and try to keep it clutched near the torq peak. I'd appreciate it if you guys would bounce some ideas around. I'm not opposed to trying something different. I can do all of the machine work, roll my own pipes, whatever....