fredd2510

wellll .. cautious way is to cut 1mm off (total of 2mm) Slightly better perf /effect from a 1.5 mm deep cut.. Deeper than that and yr on your own.. it's possible but it's a crapshoot. Lotsa flywheels have been cut thru at a 2mm deep cut.. some were ok at that...But it could be clever to keep the thing from grenading due to too much metal removal. Your choice tho :-)

A little porting?? Hey! just go and buy yourself a fair collection of small files.. NO power tools (yet) you can ruin a cyl in seconds with those things.. not for beginners..... AND ...find Gordon Jenning's "2stroke tuner's Handbook" then Read the thing untill you've almost memorised it. Then think about 'attacking' a cylinder. Porting is a V skilled excercise .. more than a few Pro tuners are errr.. not v good at it. Any fool can hog out a port.. which often does v little good at all. Calculating the transfer port angles as the exit into the cylinder is serious work.. and carving then accurately take years of actual experience... with likely dozens of wrecked cyls in the process. Realy wanna do it ?.. Read the literature, all you can get your hands on.. buy only hand tools and practice a lot..... have fun.

All interesting options. Consider a couple more : Use a pair of RZ350 cyl/ heads and their Powervalve setup. Not inexpensive, but not too pricey certainly less than a port job :-) Consider that these engines ..can.. be made to generate an honest 80hp.. (Be assured that damned few other motors manage this trick, at least those using similar displacement... and .not internet hp either :-) ..without.. altering the OEM ports. .. yeah NO port job. Why? basically cuz these come very well ported from the factory.. Mr Yama's engineers were not idiots :-) Also the Power valves manage the exhaust timings so that it has useable power over a useable range 7, 000 to 10,500 rpms.. otherwise it would be only crazy power at 9500 and above.. as would ANY cylinder using similar portings. To do this of course one needs well sorted Carburation, genuinely Good chambers, correct squish and carefull ignition setup.. not to mention a v well assembled engine. Note: one can also buy programmable CDI units and Powervalve controllers for fair pricings for these motors.. Fergit foolish 4 degree advance keys.. when one can step the curves exactly where ineeded at 10 distinct points in the rev range. Lots to learn before laying out yr hard borrowed $$ :-)