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Discussion Starter #1
Hey everyone! I'm new to motorcycling and recently picked up a 1982 xs400 Seca. I had it out a few days ago and noticed that it seemed a bit wobbly. Got it home tossed it up on the center stand, with engine off, spun rear wheel and noticed a slight wobble. Started the bike up, put it in gear and saw the same thing. The wheels are cast aluminum and I can't see any noticeable deformation. Not sure if it's bearings, swing arm related, etc... Also not sure if it's something that I can tackle or if I'd be better off having it done by a shop. Any and all help is greatly appreciated!

 

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Ace Tuner
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From what little I can see of the rim it looks like it might be running true but the tire sure ain't. If the rim is running true then the tire is most likely not mounted correctly.
There is a "bead line" on the tire right up close to the edge of the rim. Check to see if it is consistent all the way around. If it is not... You found the problem.
Please let us know what you find.

S F
 

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Or it might just be a bad tire, rare but does happen. Cheap tires might have more bad cases than name brand so what brand is it. But what SF stated is most likely the case. Look for a bead not seated properly.
 

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Discussion Starter #4
Thanks for the quick replies. Tire is a Metzeler. Its dated from midway through 2018 and still has tons of tread left. I'll take a look at the bead line here shortly. Should I just remove tire, drop PSI and try to reseat the bead? If that doesn't do it, remove tire, reinstall wheel on bike and check that it's true? Then if all else fails take it to the pros?
 

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If the bead line isn't true, you would have to not only drop the psi. But also completely break the bead. Chances are it would only be on one side of the tire, so you would only have to break the bead on that side. Of coarse if it is not true on both sides, then the bead would have to be broken on both sides. Use a lot of tire lube when reseating.

If it is the bead line being off, t he wobble would have showed up ever since the tire was mounted.
 

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Discussion Starter #6
Yep you guys were right here's the left side of the tire if you're sitting on the bike. Right side looks pretty uniform. I hadn't noticed it too much prior to a few days ago, but I also don't really have anything to use as a metric for what a "good" condition bike should be lol. So I'll remove the tire, pop the bead on that side, soap and water the tire and bead and seat it correctly. Any tips on getting it seated as it should be?
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I have an 83 Seca so pretty familiar with how they run. But first: Is yours a twin overhead cam motor, and how many gears do you have. One last check, are you doing 6000 revs at sixty mph. From there I can tell you all the things you might want to check.

UK
 

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Discussion Starter #8
Thanks Krusty!
I thought all Xs400rj/k s were DOHCs? But yes mine is. It's a six speed and I can't give a definitive answer on the 60mph rpms as my tach crapped out about 300 miles ago. It ran when I first picked the bike up for a brief period before it started screaming like a wild banshee. It sounded like the bike had a kazoo as the tach...definitely got a lot of funny looks 🤣 . I had to replace the speedo as well and noticed that the back of housing was cracked on both of them where the cables attach so I assume the gears slipped and it stripped out.

Going to try to reseat the tire hopefully in an hour or so, but have a few other priorities to square away first. Would love to have taken it out today (60 here in Ohio today!) But not sure if I'll get everything wrapped up in time.
 

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" Any tips on getting it seated as it should be? "

Remove the core from the wheel air valve, make sure the tire bead seating area of the rim are clean, lube the rim and tire bead then air the tire till it 'pops' up in place. If it doesn't seat all the way around you may have to apply more lube to any area that doesn't seat correctly and hit it with air again. Reinstall the valve core.

S F
 

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Sweet DR. The tach on mine quit too. The cable snapped and I have not found a new one. I checked my speedo with a GPS and it is quite accurate. When new at WOT the hit 10,000 in all gears. Mine can do that in the lower gears but only gets to 9,000 in top gear. I am running a five speed motor at the moment. The six speed is waiting for some work.
I asked about the engine as some folks get the model wrong. The Single overhead cam motor is a wimp that makes about 36 horsepower. The DOHC makes 45 when new. Get the tire fixed first, then I can tell you what else I did with mine. They are great bikes, worth keeping and riding.

UK
 

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Any tips on getting it seated as it should be?
As SemiFast states but the key is really soapy water. More soap than you would normally use to check for air leaks. Something like instead of 1 cap full use 2 caps. It depends on your container of course. Just don't go overboard with the soap though. Dare I say use common sense? :rolleyes: :rolleyes: :rolleyes:
 

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Discussion Starter #12
Okay quick update. Removed tire, broke bead, lubed tire and tried to re-seat the bead. I didn't hear an audible pop, but no air seemed to be leaking from around the tire. Should I remove again and try to re-seat until I hear the pop? The bead lines looked a lot better than before but still not quite perfect. I reinstalled the wheel onto the bike, and still noticed some wobble. Debating whether or not to take it to a shop so that they can check that the rim is true and properly seat and balance tire. I'll be out of town this weekend and won't have time to tinker until the first of next week. I guess that'll give me the weekend to decide whether or not I want to wuss out :rolleyes:.

HOG & SF- I brushed on a bunch of tire lube, maybe I should have used more? Or it just didn't seat? Do you pull the tire to clean the rim? There was some buildup that may have inhibited from seating correctly, I may try to pull tire clean the rim a little better and re-seat.

UK- I've found a few places that have the cables here's one on amazon https://www.amazon.com/Yamaha-341-83560-01-00-TACHOMETER-CABLE-341835600100/dp/B00AJQJNYY assuming the '82 and '83 used the same cable. Ebay also has used ones but not sure how much life they'd have in them. I found a NOS tach on ebay for $140 and haven't been that desperate to pull the trigger yet lol. I've had a blast on the bike so far. I've replaced fork seals, rebuilt front caliper, new brake lines (old lines were the originals from '82 :oops: and my were they spongy), replaced master cylinder, switched out to LED lights, and maybe a few other small things that escape me. Did you replace your rear mono shock at all?

Thanks again for all of the information!
 

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Do you pull the tire to clean the rim?
Making sure the rim was clean is a must. There is a chance something like rust or a chunk of rubber will keep it from seating. So yes, try again and this time make sure the rim is clean and smooth, then lube it up and add air. Don’t be afraid to add 10 or 12 pounds more than normal too. It might take it but cleaning it up should do the trick.
 

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Good work on the brakes and seals. I will check the part number for the tach cable. I do need a new rear shock. I have other bikes with better suspension and it shows. But it does the job. I had to change the swing arm shaft and bearings, and we can talk about that. The Feroda pads on mine are working better than the EBC. A new brake hose is on my list, but needs to wait until summer. I should check if I can get one made in the city near me. Original head light was a bit dull. Good plan with the bulb. Not sure what I used, but it is much better and works.
Wot the others said about the tyre.

UK
 

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I had a problem getting a tire to seat properly a couple years ago. I cleaned and lubed and aired it up til I got sick of it. Then I laid it out in the sun, it was summer time then. Seems like it was only 10 or 15 minutes and then "pop" it seated!
So adding a little heat with a hair dryer could be a good idea.
 

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You can lose a tire like that too if left out too long. Now don't you dare ask me how I know. All I'll add is don't forget you have it out in the sun. :rolleyes: :rolleyes: :rolleyes:
 

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Discussion Starter #20
Quick update, and happy New year! Took the tire to the shop and had them balance and take a look at it. When they seated the bead it never popped. He rebalanced on machine. One of my chain adjuster bolts was bent so I picked up a new one as well. Put the tire back on the bike, tried to adjust to least amount of wobble. Torqued everything to spec, started bike and the wobble was still there. I took off the chain guard and noticed that one section of the chain looked like it had an inward bend so I pulled the chain, brushed the worst of the grime off and left to soak. Without the chain on I spun the tire and noticed what may have been some lateral movement between the sprocket and frame.
May just be because the axle isn't currently torqued to spec? I'm going to head back out to the garage shortly, clean the rear hub assembly/sprocket, brush and lube chain again and try to get it all back together before next year! Will update after that.
 
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