rbm300ex
03-16-2007, 02:12 PM
I just had what described above happen to my built '00 300ex. The stock cyl. sleeve got pulled down into the lower case and partialy dissintegrated - sleeve works way down low enough that rings catch on top of sleeve and WHAMO on the down-stroke - alot of little iron chuncks & pieces in the bottom of the lower end & it locks up. I was trail riding normal and the thing just stopped. I thought I threw the drive chain at first, but nope, that was ok, got it home and thought maybe the cam chain was the culprit cause that I thought may have been the weak link as it was not replaced when I rebuilt. Well upon breakdown, it was clear what had happened - just as described. Searched the forums & have seen others had experienced this w/300ex motors but nothing mentioned re: fixing it.
Well, after all the above, I'm going to rebuild it again, I realize it will need a new piston, sleeve and the basics but what do I need to do to get the lower end cleaned up. Will it mean splitting the cases and cleaning everything or what - can it be done another way? Crank bearings? I realize some is determined by extent of actual damage but doesn't appear to be anymore than described. I'm wondering what the procedure is to begin the cleanup/rebuild. What would you experienced engine builders do? I have the Clymer manual to guide me into it too but never gotten into the lower end.
Thanks much-
Randy
:confused:
Well, after all the above, I'm going to rebuild it again, I realize it will need a new piston, sleeve and the basics but what do I need to do to get the lower end cleaned up. Will it mean splitting the cases and cleaning everything or what - can it be done another way? Crank bearings? I realize some is determined by extent of actual damage but doesn't appear to be anymore than described. I'm wondering what the procedure is to begin the cleanup/rebuild. What would you experienced engine builders do? I have the Clymer manual to guide me into it too but never gotten into the lower end.
Thanks much-
Randy
:confused: