Greetings! If someone has a crankshaft from FZR250 3LN laying around please take a nice photo of it from both sides. I'm interested in size and direction of the factory oil hole chamfers on the rod journals.
No chamfers on main journal oil holes from what I see. Would you be willing to unbolt the rods and take pics of the rod journals?
sure will but will be in a cple of days as having flooring fitted and everythings all over the shop atm
You might need to have a look at the issue of oil feed with the 250. The 400s are reported to have this problem. "If you measure csa(cross sectional area) of oil loss at rod ie:area of pin minus area of rod inc shells, times 2 for both sides . Plus oil loss for outer main brg(since these are fed together). This is the total area for oil loss assuming the crank is not moving(no centrifugal pull). A rule of thumb is that the supply csa is at least a third larger than the loss csa. This also assumes no 90 degree bends etc. If you look at the oil feed in the btm case it has an arduous path to the outer main and consequently the big end. The oil rises in a 5mm drilling (where the restrictor jets are) and then horizontally in a 6mm hole and then up again at 6mm to the outer big end. The 5mm drilling has to be because they wanted to put a M6 thread in it for the jet. Anyway, take the 5mm hole out to 6mm and then use a thread repair, Time sert or Helicoil, to restore the thread for the oil jet. The reason the main is OK is because it always has sufficient oil and little centrifugal force, however the big end throws the oil away at a considerable rate .Remove more than you are putting in and bang! I have seen hundreds of FZR's with outer b.ends gone. All modified as above sorted them out without fail. " from http://www.bdkraceeng.co.uk/Bike1.html
