arcticflipper Posted July 13, 2006 Share Posted July 13, 2006 Not an XX, but I don't know where else to go for answers on this problem. 4th gear has been undercut twice. and it's still not right. What is happening is that when you are in 4th gear, and you close the throttle the bike starts shaking on the gearbox. Does that make any sense? Any Ideas as to how to get this resolved? Have also tried a brand new 4th gear, but still under deceleration it's studders, shakes, don't really know how to explain this.. Quote Link to comment Share on other sites More sharing options...
bartonmd Posted July 13, 2006 Share Posted July 13, 2006 I'm not sure, but it may help to know which other bike it's happening on... Mike Quote Link to comment Share on other sites More sharing options...
arcticflipper Posted July 13, 2006 Author Share Posted July 13, 2006 ZX9R '96 Model I'm not sure what is meant with undercutting the gearbox. As far as I know that normally means that the selector dogs are worked on because they can not select or slot correctly with the gears? This is normally done when you are slipping gears or missing gears.... Now that's not the problem that we have experienced with the 4th gear. When you decelerate while in 4th gear, it feels asif the bike is jumping? Asif the gear catches and then doesn't, and then catches again.... Can select the gear everytime without any slipping or problems. It does not jump out of the gear either. Quote Link to comment Share on other sites More sharing options...
bartonmd Posted July 13, 2006 Share Posted July 13, 2006 undercutting the dogs is basically when you use a mill to shape the dogs in such a way that the "ends" of the dogs are farther out than the rest of the dog as it gets closer to the gear itself... It basically makes the dogs more like "hooks" Shaped something like the hideous line art below with the part sticking up being the dog. It basically makes it so that the gears "want" to come together once the dogs catch one another as the shifter fork slides the one gear next to the other one, so that they now rotate as one right next to each other, with the dogs keeping them rotating the same. 1 ''''''''' ____ ______\ ''''''|_____ I suppose what could have happened is, they could have "overcut" (like the opposite of undercutting, I guess) the back sides of the gears for some reason and the opposite side of the dogs are pushing each other apart, like the second hideous line art below... 2'''''''' ____ _____\ ''''''\_____ I suppose they could have maybe undercut the wrong side of 4th last time, and it broke the tips off of the dogs against the flat surfaces of the back side of the teeth on the other gear, so it ended up looking like the second line art above... There's really no way to tell other than taking it apart again, as far as I know... I honestly don't know, but just said what sounds plausable to a guy who isn't a gearbox machinist... Although, if they had to do it twice, I'd immagine the person who did it isn't a "real" gearbox machinst either... Mike Edit: the line art got worse... I had to put the damn apostrophies there because when I posted it, it just took out the spaces I put in... disregard all apostrophies ('''''') Quote Link to comment Share on other sites More sharing options...
arcticflipper Posted July 14, 2006 Author Share Posted July 14, 2006 Thanks man, is making some sense now. I will strip it this weekend and have a look to see what they did and what the condition of the 4th gear is like.... Will let you know. Quote Link to comment Share on other sites More sharing options...
JohnS Posted July 14, 2006 Share Posted July 14, 2006 I think you will find one or more worn and perhaps burnt selector forks. This can happen from a constant loading on the fork. Can be a rider who preloads the shift lever all the time or a badly setup gearbox. JohnS Quote Link to comment Share on other sites More sharing options...
OZDave Posted July 14, 2006 Share Posted July 14, 2006 Just talking to a guy tonight. He has a 2005 cbr1100 with the problems you described and it was a fucked gearbox. Apparently the selector forks were worn very badly and did other damage as well. He has had other Blackbirds before with no problems so it seems it was a badly setup box from the factory. All covered under warantee. I've never heard anything like this before about Blackbirds. His description was "It felt like the chain was jumping over the teeth on the sprocket". I know yours is not a cbr1100. but it sound like a similar problem. Quote Link to comment Share on other sites More sharing options...
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