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"I personally own a 850 special, and I can tell you that "shaft jacking" is more a myth than a reality."

Bullshit. It's all physics. I've owned two XS750E and one XS1100E and I can tell you, it is real. It was so bad that a high-rpm first or second gear throttle chop would hop the rear wheel off the ground. You're either riding it like a pansy or have hard-tailed the bike.

"The seca 650 I had for a while had no lash"

True, to a point. It still did have a shaft-jacking effect, but was much subdued. I had one of those too.

The first-gen Yamaha shafties used a constant-velocity universal joint, and later ones used a more traditional u-joint. I'd never heard of, seen parts of, or witnessed any Yamaha shaft final drive that locked up. Doesn't mean it never happened, but I'd say they were pretty solid from a durability standpoint.
 

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my GS850L was a bucking bronco. you could literally feel it rise and fall. The R80Rt beemer isn't as bad but I do get why they call all airheads rubber cows - the jacking motion and the rotational effect make for an interesting ride quality.

A lot also depends on the condition of the bike. If you are on worn out springs and bad swingarm bushings - you are gonna feel that. If the bike is nice and tight all around it won't be as bad.

You can get used to this stuff you know. After a while in the saddle you don't even notice it. All old vespas lean 15 degrees to the right when not on the throttle and straight up when you are. After a couple of days you don't notice it anymore.
 

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I've heard on more than one occasion about the XS11 final drive locking up - not sure if it was the actual final drive unit or the universal at the motor but apparently it was whilst the bike was being ridden and it locked the wheel. Apparently. Never saw it, so I won't say it's gospel.

But I did have an XJ900 universal let go (not on me, but on the guy I'd just sold the bike to). Made quite a mess. We went halves in the repair bill because he wasn't a dickhead and swore he didn't abuse the bike.
 

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I've heard on more than one occasion about the XS11 final drive locking up - not sure if it was the actual final drive unit or the universal at the motor but apparently it was whilst the bike was being ridden and it locked the wheel. Apparently. Never saw it, so I won't say it's gospel.

But I did have an XJ900 universal let go (not on me, but on the guy I'd just sold the bike to). Made quite a mess. We went halves in the repair bill because he wasn't a dickhead and swore he didn't abuse the bike.
Naw this lockup is common at the middle drive. Gear oil leaks into the crank and it burns up.
 

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sorry...the gear oil from the bolt on middle drive leaks into the crank and the middle drive runs dry and eventually locks. I believe it leaks through the bearings between the final gear housing and the crank. Should have been more clear.
 

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Discussion Starter #27
Hey guys, I have been messing with the bike some, but have been short on free time because I bought a house that needs some work as well.
The motor runs on the bike, but poorly because of dirty or damaged carbs. I have a guy offering to sell me some known good mikuni's for it, so I'll probably go with those. My front brake is locked up, though, so I haven't been able to ride the bike at all yet. Does anybody know if I can just disassemble the calipers and clean them up with Emory cloth or something, replace the o-rings and call them good?
I joined the Yamaha triples forum, so I'll ask over there, too. It also seems like a good place to find parts as well. I think I'm going to get a standard rear wheel and tank if I can, and try to find some super bike or dirt bike bars that I like.
The seat is the last thing on the list, but it will be for sale once I figure out the direction I want to go with that.
The bike has some Dunlop tires on it that are in good shape, but they're a couple of years old. Does anyone reccomend avon tires? I have crashed with Chinese tires before, but I can't afford the pirelli's I normally put on crotch rockets. I plan to push the limits of this bike once in a while, and sticking to the road is a good thing....
 

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Hey guys, I have been messing with the bike some, but have been short on free time because I bought a house that needs some work as well.
The motor runs on the bike, but poorly because of dirty or damaged carbs. I have a guy offering to sell me some known good mikuni's for it, so I'll probably go with those. My front brake is locked up, though, so I haven't been able to ride the bike at all yet. Does anybody know if I can just disassemble the calipers and clean them up with Emory cloth or something, replace the o-rings and call them good?
I joined the Yamaha triples forum, so I'll ask over there, too. It also seems like a good place to find parts as well. I think I'm going to get a standard rear wheel and tank if I can, and try to find some super bike or dirt bike bars that I like.
The seat is the last thing on the list, but it will be for sale once I figure out the direction I want to go with that.
The bike has some Dunlop tires on it that are in good shape, but they're a couple of years old. Does anyone reccomend avon tires? I have crashed with Chinese tires before, but I can't afford the pirelli's I normally put on crotch rockets. I plan to push the limits of this bike once in a while, and sticking to the road is a good thing....
Those calipers are pretty easy to rebuild if you can get the piston out. Try installing a grease fitting where the bleeder was and force it out
with a grease gun. Worked for me a few times.
Avon AM26s are great tires. If you want cheap tires that stick, Fullbores worked great in my Sporty.
 

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So you crashed on Chinese tires before...are you blaming your crash solely on the tires?

I've crashed on just about every brand of tire, bias, radial, cheap and damn expensive. Wasn't the tire that caused the crash.
 

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Discussion Starter #31
I truly blame my own carelessness for my crash, although with better/stickier tires my delayed reaction to the guy driving on my side of the road In a curve might not have resulted in my bike sliding out from under me.
the carbs he has are the round slide smooth bore 29's I believe. I had a set on my old kz1000, and they were great. These arethe same thing just set up for a yammy triple.
Thanks for the grease gun tip! The pistons slide out pretty well with just the master cylinder, just won't slide back in to let go of my rotor. I opened the bleeder and they still wouldn't let to, so I blame the caliper rather than the hose, although I will replace all the hoses with stainless next month when I have some extra scratch...
 

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"I personally own a 850 special, and I can tell you that "shaft jacking" is more a myth than a reality."

Bullshit. It's all physics. I've owned two XS750E and one XS1100E and I can tell you, it is real. It was so bad that a high-rpm first or second gear throttle chop would hop the rear wheel off the ground. You're either riding it like a pansy or have hard-tailed the bike.

"The seca 650 I had for a while had no lash"

True, to a point. It still did have a shaft-jacking effect, but was much subdued. I had one of those too.

The first-gen Yamaha shafties used a constant-velocity universal joint, and later ones used a more traditional u-joint. I'd never heard of, seen parts of, or witnessed any Yamaha shaft final drive that locked up. Doesn't mean it never happened, but I'd say they were pretty solid from a durability standpoint.
I drove my 850 to work the other day, and as I was driving it I thought about the shaft jacking. I cracked the throttle a few times and now I agree if you think about it then you will notice it. I can't conceive of it actually hopping the wheel off the ground, but I will agree I don't drive it like I'm on a suicide ride.
 

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i just finished my 850 special, i kinda like the way it looks... & its my bike, i call it whatever i want... cafe, bobber...rat bike...
 
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