Motorcycle Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
what happens if you install a piston backwards with the IN mark facing the exhaust? engine rotates smoothly by hand so i dont think the valves are going to touch.. im just second guessing myself as thats one thing i did not notice when i rebuilt it. :thumbsdown:
 

·
Gone.
Joined
·
17,857 Posts
Other then a valve hitting a pocket, two other reasons some pistons are directional is because oil passages in the piston or rod assembly will only line up correctly if it's facing the right direction, and also some pistons have a connecting rod that's slightly off center. That is to take into account various angles and directional forces when the piston is getting pushed up by the crankshaft or being pushed down by combustion, so it stays straight in the cylinder bore. In that case if you reverse the piston it will start to wear unevenly and try to rock and wiggle, resulting in piston slap and further damages.
 
1 - 5 of 5 Posts
Top