Situation: I bought a 450 used and it ran fine for a 2 days of riding. Then I take the bike to upstate NY and play around the roads for about two hours. Everything is fine. Then the next day I play around for another hour and then its time to go on some serious riding. Top the bike off with 94 (the previous owner used half U4 half 93). I take off down the road and the bikes running good and then starts to lose power suddenly, then the back wheel locks up. I kicked it for about an hour total that day with only backfirering. Upstate was about 25 degrees difference colder and within 500 feet of my home altitude. Solutions tried in order: Changed spark plug -no effect Checked spark -plenty Tried different gas -no effect Pulled flywheel - keyway intact Checked Timing - Correct Checked all electrical with multimeter -Everything fine but coil (100 ohms out) Replaced CDI with revbox (manuals last option) - We got it to run but only for 7 seconds and then not again Cleaned Carb thouroughly - No effect but 178 Main (seems large? led me to belive I should try straight U4.) Got raped on U4 -got the bike to run twice once bike idled low with choke on fuel screw 2 out then stalled on its own. Then got bike to run with gas off fuel screw seated no choke and holding the hotstart. Got a nice solid idle, then touched the gas and the bikes rpms shot up and stayed there so fearing leanness I prematurely ejaculated and hit the killswitch instead of working it out. Bike has not started since under any of the same conditions and just lets out some nice deafening backfires complete with fireball. The motor still has serious compression ( Between me and my friend who is well versed in motors we kicked the thing over 3000 times and it never got any easier). The coil measured 100ohms over the specified 100 ohms does anyone belive that could cause this kind of problem? I personaly do not. I forgot to note the other jets in the carb but 178 seems kind of rich even for oxygenated fuel. Im at around 1200 feet in my home town where the bike ran perfectly. All I can think is and Im exausted and have run out of curse words and ideas. My friend who helps me keeps telling me I should have gotten a Honda and I really dont want him to be right. Im about to light the thing on fire and ghost ride it off a cliff. Thanks for the help.