to rebuild or not?

[yamahaluke]

Last October I blew up the engine in my 1981 xs11. I tore it apart to find I had melted a hole through the #2 piston. I rebuilt the top end using pistons, jugs, and head I bought off ebay from a guy that claimed they were very lightly used and off a 79. I got it all back together and rode it pretty hard, admittedly probably to early after rebuilding it. So, the murphy conspired against me last Saturday and while flying (not riding, what I was doing was to fast to be riding), to work I blew past a harley bagger, around about 100 mph and just after clearing him started losing speed, engine rpms remained the same only speed dropped off dramatically, until BANG!!!! blue lightening shot under my right knee. The bike slows to a stop and the harley riding. . . mama said if you have nothing nice to say don't say anything at all. . . rides by flipping me the bird. Took her all apart and I collapsed the dome on pistons 1 and 2 and burnt through three and fired through the head gasket on four taking a crater out of the aluminum surrounding the cylinder. I have a cylinder and two extra pistons, I can get a gasket set on ebay pretty cheap. I need another piston. Problem is I need to know why I keep melting pistons. I am a very very very big guy 502 lbs at last check up. I ride hard. I am thinking about hanging it up with the xs11. What should I do? Why is this happening. I should mention I am running the aftermarket black coils from mikes xs eleven, and filter pods. I cleaned the carbs when I rebuilt the engine, but I am wondering if either A. I am just to big and pushing it to hard, B. need to rejet carbs to account for filter pods (running stock 4 into two exhaust) C. Slight hiccup in ignition causing a funky idle and noticeably irregular ignition on cylinders 1 + 2 until higher rpms (after recent reading I believe this to be a screwed up wire coming from the pick up coil). Any help would be appreciated.

[Ken Talbot]

My first guess would be running way too lean. Was there anything left of the plugs when it died so you could see what colour they might have been?

[yamahaluke]

thats the scary part, light brown to a light greyish color no major noticeably wierd deposits like silver specks or anything

[WMarshy]

What kind of RPM were you turning? Sounds like its too lean at WFO, no other reason to melt a piston like that. Although Im half your weight, I ride my bike hard all day long and dont have any problems. Im sure Im not the only one too... Not sure if this applies but, make sure you let it get fully warmed up before romping on it.