XJ550 vs XJ750 seat vibration

Hey guys --
I have been riding my xj750 for a thousand miles or so and never feel vibration through the seat. Buzzes like hell around 4.5K rpm, but I guess they all do On my new xj550 around 4K I get a serious vibration through the seat. It sounds smooth and pulls hard, so I was wondering what is normal. I am thinking I am going to have to replace the foam 'cause my a$$ will be asleep in an hour!
-- thanks

 

In every gear or cruising in 6th?

 

that vibration is normal .. mine is pretty radical at that range too...lots of guys who know on here say its they way the all are, just be glad you dont have to maintain that rpm for any length of time....

 

mine doesn't vibrate.... i do have a different bike.... and what do you mean you dont have to sustain around 4K rpm's for a long time? my bike does 60 at 4500 rpm's..... you're there ALOT, i'd probably sell the thing if it vibrated bad at cruising speed.

 

yes and no. I have the luxury of being able to ride two different 550s back-to-back, one an '81 and one an '83. The '81 has 20K+ miles on it, the '83 only 7200. Both are in a reasonable state of tune, the '81 is about as good as a 550 gets, the '83 has a way to go yet. The '81 is quite a bit "buzzier" than the '83. I do know this: I changed handlebars on both bikes. The original bar from the '81 was just hollow, like normal. The bar from the '83 had WEIGHTED ENDS. I suspect that Yamaha may have been taking vibration-fighting steps between the 1981 and 1983 model years; the difference may have even extended to things like the motor mount bushings, although they carry the same part number. I would really like to replace the rubber motor mount bushings on the '81 but they are discontinued by Yamaha and I don't know of an alternate source. (Pretty sure Chacal doesn't carry 'em.) I had seen a post a while back from another 550 owner in regard to the possibility of the rubber mount "dampers" being worn and causing excessive vibration to be transmitted. By the way, both are SILKY SMOOTH cruising at 6K rpms...

 

Thanks guys. I won't have it up to highway speeds until I rebuild the master cylinder (parts on the way -- thanks chacal!). I do tend to ride below 5k RPM on the 750, but reading the posts here I understand I am at the bottom of the curve! I am amazed at the difference between the two bikes, but I think bigfitz hit it on the head -- it is a helluva lot 'buzzier', but still fun as $hit to ride. It's for my gf anyway . . .

 

Hey, I LOVE the 550, I'm a chain drive guy and this thing will whump my Norton in 3rd gear. I ride it to work at 80+mph on the freeway, and the buzziness is gone at that speed. Plus it's ROCK STABLE at any speed which quite frankly surprised me, as did the two-stage powerband.