I need to get to the crank and conrods. On these engines, does one need to remove and take apart the top end, or is there a way to split the engine in half from the bottom end. I am looking at the manual, but it is such a bad copy that I cannot tell. I'd prefer to hear from someone who has actually done it .... <!-- s --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s --> Thanks
All the bigger FZRs (400-1000) have two bolts under the cylinder blocks; to get at them you need to tear the head and block off. I haven't done it myself, but nothing I've seen or read suggests the 250s are any different.
Correct. Verified by having a complete tear down completed. This must be one of the dumbest engineering solutions from Yamaha ever .... there's no reason why they couldn't have shift the bolts location and drive them from down up, so top end can stand untouched. BTW, do you know anything about the conrod bearings and how the colors, they refer to in the shop manual, correlate to the 4 different parts options in the parts manual? It has been really pain to figure this out. I need 3 green and 1 brown, but I cannot order them by color. It is either 00 to 30 at the end, and I am not convinced that the order of colors is the same as the order of the different shells. Again, not very smart from Yamaha .... Thanks
Yamaha seems to have a pattern that they stick with for con-rod and crank journal bearings: -00 Blue, -10 Black, -20 Brown, -30 Green, -40 Yellow etc. I've checked this on several years of Yamaha bikes, including a '90 FZR400A, a 2002 FZS1000P, and a 1987 FZX700. Many people have commented on the WTF-factor regarding those two special little bolts ... <!-- s:alcoholic: --><img src="{SMILIES_PATH}/icon_all_coholic.gif" alt=":alcoholic:" title="Alcoholic" /><!-- s:alcoholic: -->
You say seems ... how confident are you? LOL ..... I know racers here who out of desperation try to ignore the bolts to only find oil leaks ..... it's really a piss-off engineering work. You want to know another kicker? The conrod on my trouble cylinder is the only one where I cannot read the ink stamp number, so I am guessing there as well ..... no color coding left on the shell, no number left on the conrod = possibly bearing failure 5 mins into a rebuild engine running. Thanks Yamaha ... Love the bike, but wish you engineered/assembled/documented certain things much better .... I am pretty close to certain why the bearing failure. The jet restrictors on the crank oil passages were totally loose, almost all the way out ... there's no way this was ever lubricated the way it was supposed to be. Such a stupid assembly thing, yet so costly one ....
