I disassembled the entire power valve system on my 1999 kx250 for cleaning and now I'm not sure how to get the exhaust valve timing back to where it was.
ok i figured out the basic concept of the thing. I am just trying to figure out what is considered open and what is closed. kinda hard to explain, but im not sure what position the "drum" valves should be in.
I have it to where it seems right, but there isn't as much movement in the valves as i expected. When "open", the passage from the cylinder looks about 75% open. when closed, there is still a slight gap where air can flow out (about 25% open).
I am pretty sure this is right, but i'm trying to avoid the hassle of taking it back apart and buying new gaskets to fix my mistakes.
Hmmm. I'm not sure on that. Seems to me open should be unrestricted. On my rm it didn't restrict the flow as much as that when closed. I'm thinkin maybe 50%.
in the open position it should be 100% open or high rpm will run flat and in closed position the valve should be, more or less, 1.5mm away from the piston or the bike will not get low end power...
if not get full travel then it must have carbon or burrs from the use... open and check...
for the timing, eric gorr´s book "mx and off-road performance handbook" have a very good explained procedure- great general info and inexpensive... check his site...
for the gaskets, mainly because usualy i´m only able to find kit´s, i buy gasket paper and cut them... it´s cheap, you only have to care about thickness and have patience...
I don't know what the problem was, but I unassembled it completely and started over. I'm thinking it could have been a peice of carbon or something making it stick because it works 100% fine now. I found the timing on eric gorr. thanks guys
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