"Loose" feeling when turning/ leaning and drag at highway speeds 81 kz650

I have began to notice a softer feeling in the rear end when i lean into a turn and in the middle of turning sometimes it feels like the bike almost "shifted" slightly. i checked my swing arm by moving it horizontally and there is a tiny bit of play hardly any but under full weight of the bike and me riding it i could see there being an issue. it seemed like it would pivot left and right not the whole swing arm shift. also when i get to highway speeds i notice a drag like i hit a gust of wind but there is no wind. i know the list of possible issues could go on and on but wondering if these two could be related or not. any ideas on what to check can help! thank you!

Usual suspects are-
Low tyre pressures.
Wheel bearing play.
Swingarm bearing play.
There should be no play in the swingarm so that needs sorting out first.
Any movement at the pivot will be amplified at the wheel.

Does the drag sensation feel like a lack of power? I'm thinking maybe the engine is having problems at speed from fuel starvation or ignition system issues.

The loose feeling could be the old old old suspension. My 650-CSR isn't that great in some long sweeping high speed curves. If there are any bumps, the bike kind of pogo sticks. The rear end play could be the problem. I just grabbed my rear wheel & tried tugging on it side to side and it is rock solid with no free-play whatsoever.

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Check the steering neck bearing for play or any kind of stucking movement

Also make sure that your rear axle is tight, if it isn't when you hit your back brake the tire will shift a little and feel squirrely

sorry its taken so long for a reply. i looked into the rear tire set up a little bit. found that the spacers on the left and right were swapped. got it fixed and cleaned and lubed my chain and it seemed to help a lot. for the lag, i have been having the similar issue but now instead it seems like its about to die when it hits that point. even happened at a low speed when i tried to get on it and it just didnt do anything just almost stalled. so it seems im having issues at full open throttle. what should i inspect for that. as for the squirrly feeling, i looked at my rear shocks and noticed the previous owner had cut the springs on either side to lower it but when they cut it, they didnt cut it flush, just cut a coil in half, which over time with me riding it has kicked the springs sideways and now they are rubbing on the tube inside it. im thinking this has to be most of the feeling. i do have another set but i dont have a vise to put a new bushing in the top because one of them is missing. i also noticed while fixing the swapped spacers that my chain has been eating at the outside of the sprocket a little bit had to have just started because it doesnt seem too deep. unless the sprocket is supposed to have an indentation of the shape of the chain links. i will post pictures of the shocks and my sprocket soon. could the chain tension cause the eating of the sprocket? (p.s) my chain doesnt show any signs of damage from the rubbing but it is hard to get the chain to stay in the middle of the sprocket.

The first is the indents on the sprocket the others are the shocks being cut and kicking out. I did notice today that when I downshift and hit the brake it felt like it "drifted" I didn't look at the axle marks to see if either side moved but i don't think it did. If it didn't move what would be subject to look at? Wheel bearings?

The sides of the sprocket teeth should be beveled, but I can't tell if yours are worn.
You could compare yours to new or NOS sprockets on eebbaayy.

Shocks. To swap shock bushings I used a c-clamp & socket.


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As martin_csr determine, the rear sprocket tooth side wear looks like the rear wheel (sprocket carrier) is not proper centered in the swing arm.
I have seen a lot of bikes where the collars and spacer are switch from left to right side and vice versa, internaly missing bearing spacer or replaced with unknwon bike parts, the list to long for a write up...

I call them Suicide bikes...

True!
Having the spacers and even the chain adjusters oriented correctly is a must for proper chain and sprocket wear. The picture below shows the condition of the original engine sprocket on my 1977 KZ650-C1. The rear sprocket had similar wear. That photo was taken when I replaced the sprockets and chain at 36,000 miles. I found that the chain adjusters were installed incorrectly, and that error had happened when the bike was new. Unlike some other KZ models, on the KZ650-C1 the two chain adjusters are intentionally different in that one that goes on the right hand side has a spacer attached to it and the one that goes on the left side does not. Since the chain adjusters had been mounted on the opposite sides instead of the correct sides the rear wheel was offset a bit, and that’s what cause the abnormal wear to the sprockets. After finding and correcting the problem I installed new sprockets and chain, and now after 25,000+ miles there is zero abnormal wear to the new sprockets. Ed

I did discover the spacers on the left and right were swapped it seemed to help but I couldn't tell if it's beveled or worn. It seems to be beveled and it seems I have the chain half a link off bc there is a "triangle" that should go between the links and it is currently going in the middle of the links. I don't know if that would cause any type of issue. I can definetly tell a difference now with the spacers in correctly. From the manual diagram it looked like all parts were there the feeling isn't as bad but still get it occasionally. The rear axle marks don't seem to move when I get the feeling but it feels like it did. I'm not exactly sure what kind of wear to look for in the bearings but they seemed fine. The spun freely, the casings didn't move or anything. I put some grease we use on aircraft wheelbearings in it. Just not sure exactly how to get the wheel set %100 correct and the manual is kind of confusing on how to determine chain tension. It just says 20-30mm vertical movement but i dont know exactly what spot to set the measure point on the links. (Top, bottom, or the rivets) and if it's saying the measurement should be the entire movement (pushed down to pushed up) or just one way. (20-30mm pushing up on the chain or pushing down) sorry half a hard to explain my exact thoughts without pictures haha

Drive chain. find the tightest spot in the chain and measure the total up & down movement midway between the sprockets.
There's a drawing in the 1981 KZ650 manual. pg 2-12 (a pdf is available). I set the slack to 1" which is about 25 mm.

Slack. I use a wood folding carpenter's ruler taped to a wood block. Put the ruler behind the drive chain, then push up on the chain. look at the measurement above the chain. this is easiest & common sense. remember that number or put a piece of masking tape on the ruler. Then pull down on the chain & look at the measurement, again looking above the chain, since this is easiest. If you look at the measurement above the chain when pushing up & below the chain pushing down, then the slack number you get will be the total slack plus the height of the chain. you don't want that.

Note: you have to find the tightest spot in the chain first. The carpenter's ruler frees up one hand to rotate the wheel & the other to push on the chain. I put a couple of paint marks on the chain, so that I know that I've spun the wheel all the way around when checking. The paint marks also speed up lubing the chain. testors model kit paint in the little jars.
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