250r top end piston/rings big problem
#1
My buddy just finished rebuilding his top end on his 250r. He had the cylinder bored and honed and put in a new wiesco piston. The reason he had it bored was because the top piston ring must have hit the port and broke causing scoring. So he put it together and rode it only a couple times. He immediately noticed that it wasn't idling properly (kept stalling). Then he was riding it and it made a horrible noise so he shut it off. I towed him back and he pulled the top end off. The same thing happened again. The piston ring must have hit the port again. The ring was all broken off in the exact same spot. What could be the problem? Why would the ring be catching on the port? How can he correct this? I have some pictures of it if it helps. He's pretty frustrated right now. thanks for any input.
#2
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#7
I've seen total absolute hack jobs from Billy-Bob Bobby-Bob types, and I've seen actual good well planned and executed work too...Just sometimes ppl think that more is better..."Well I dun wy-dend my exhost til it touched them thar transfir ports, shoot, I dont know why them pisstun rings stik out in the exhost port" Then I've seen "My analysis and action plan was that I raised my exh 1.5 mm, and widened it to a maximum of 70% of bore size, I reshaped and aimed the main transfers more to the center, with a flat roove to be more biased to top end power, I however, did have the boost port open 2 degrees prior to main and aux transfer to help with the loop scavenging at lower RPM's"
You see all types...
Any pix yet???
You see all types...
Any pix yet???
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#8