Old bikes, trust, and wobbles

I've had my brain eaten by the FJ1200 to the degree that I traded the 750 Seca in on it. I got what I thought was a ready to ride bike. What I forgot was that it was still almost 30 years old (it's an 86).

The FJ is kind of the ultimate development of the 550 Seca. Sporty, chain driven, with Mikuni carbs. No YICS, though. It also inherited the anti-dive system of the 750 Seca. The engine is the familiar transverse four, except bigger.

Once the initial excitement of the new bike waned, I started noticing things.

On a hot day the idle would climb to 2500. That was resolved by a carb sync, which also made the bike vibrate less, suck less gas, and in generally be a much more pleasant beast.

Restoring the original bar weights cut the vibration so much, it's not even funny. I guess the Yamaha engineers knew what they were doing a bit better than my bike's previous owner.

The front tire was a little bald. I knew that when I was buying the bike, so I didn't wait too long to get a new one. However, when I took off the wheel I found the brake pads to be on their last legs. New pads went in pronto, and vastly improved the braking. Also, I was hoping the tire would take care of the occasional wobble I had.

Then, my oil light went on. On the FJ the oil warning is for level, not pressure, so that just meant it was a little low. Oil change was a revelation. What came out of the crankcase looked like something you might see squirting out of an oil well. The filter o-ring was hardened and compressed.

Then, with the engine quietened down, I started hearing this rubbing noise. I couldn't quite pin it down, so I decided that the chain might be loose or worn. Ordered a new chain and sprockets. When I went to pull the rear wheel, I got quite a surprise. The axle cotter pin was missing, and the wheel had some movement side to side. That was why the wobble was there.

The bearings looked like this:




With new sprockets and bearings the bike is very nice.

The moral of the story is, even if the old bike looks to be in running condition, it's still an old bike, and whatever the seller says cannot be taken on faith. Sometimes they will swindle you, but much more often they have no idea themselves. Assume it needs work, and proceed accordingly.

 

Goiod write up there JP.
I've had 3 FJ's and know them inside out. Got a bit bored with my last one and decided to build an XJR with whatever would fit from the old FJ.
Anyway, a word to the wise mate, don't forget the sprocket carrier bearing, that will cause an un-nerving chain rattle/vibration when it goes West. :wink:

 

Sprocket carrier? If you mean the thing the rear sprocket bolts to, it's where the larger of the two bearings in the picture came out of.

 

Yeah, that's the one.
What about the other bearing from the wheel then?

 

I replaced them all. There is a nifty kit from All Balls Racing that has the three bearings and the two seals. I just didn't put the third one in the picture because it wasn't as horrible as these two. BTW, just so you know - I did not remove the side covers from these bearings. They just weren't there. I'm guessing they disintegrated.

The smaller bearing was the right outer one. It was the worst of the lot. You can actually move the inner race a visible distance.

 

Good stuff then mate.
Some bearings you can buy without the plastic covers so that you can re-grease if desired.
Some people prefer them. I just use whatever i get when i go to replace them.

 

The bearings with the "side covers" are sealed bearings.

Not all replacement bearings are sealed; the OEM bearings either weren't sealed or may have been only "sealed" on one side.

You should have replaced all three. On the chain-driven bikes there are two in the wheel proper (separated by a spacer) plus one in the "sprocket carrier" flange.

Here's the 550 rear wheel bearing piece; it pretty much applies: http://xjbikes.com/Forums/viewtopic/t=35134.html

If the third bearing is the one that goes in the sprocket flange, I'd replace it too.

 

I did. The smaller bearing in the picture is one of the two in the wheel proper. The larger bearing is the one from the carrier.

The reason I think the seals disintegrated is that the other bearing actually had a seal, while this one didn't have any. The big bearing had a seal on one side and was marked ZZ, which, if I remember right, indicates a bearing with metal seals on both sides. Possibly someone tried to regrease it and destroyed the seal in the process.