New Chain, Sprockets, Rear Tire Advice

[herostar]

I'm pretty sure my '81 still has the original chain and sprocket set, and I'd like to replace them.

I also need a new rear tire.

I want to replace the rear brake pads while I have it all apart, what else should I look at (ie bearings, etc)?

Any recommendations on what to buy???

[cowboyup3371]

Yea, I would look at doing both sets of bearings, chain, BOTH sprockets, tires if needed, look at your fork seals, springs and shocks if needed.

I've done all but my seals, springs, and shocks. Need more money first

[herostar]

Yea, I would look at doing both sets of bearings, chain, BOTH sprockets, tires if needed, look at your fork seals, springs and shocks if needed.

I've done all but my seals, springs, and shocks. Need more money first

I was planning on doing both sprockets.

Fork seals, springs, and shocks are done already

[Tom R]

How many miles?
If you mean wheel bearings, they may need replacing if they feel notchy or overly tight when you check them. I replaced all the wheel bearings on my bike when I bought it, but it had 25,000 miles on it and some of them were notchy.
Look at the brake pads first, they may be fine. Better money would be spent on master cylinder or caliper rebuild kits IMO.

[pete]

Check your swingarm bearings out as well and give it a good lube job.

When I first got mine, it felt like there was a hinge in the middle of the bike going around corners and I discovered it was completely dry in there and some of the rollers in the roller bearings were dust.

[herostar]

Thanks for the advice. The bike currently has ~13,500 miles. I have service records showing it was ridden ~10,300 miles by 1984, then pretty much sat until I bought it in 2009 with 11,600 miles.


The rear tire on the bike now is a 4.0-18. What is the equivalent of a metric tire? I was thinking a 120/90r18 might work... I found a dunlop 404 at a local shop in that size.

What kind of wheel bearings are good to use? I saw a $10 kit on ebay for front bearings...

[cowboyup3371]

Check out Z1 on their bearings...I didn't pay much for my wheels.

[Jagir]

On my 81 GS 400, I've bagged out 2 chains in about 15000 kms. This seems excessive.

The sprockets look fine (and looked fine when the chain only was replaced last), but there is definitely a tight spot in my chain when I spin the wheel.

I have spun the wheel and eyeballed the chain in relation to the other parts of the bike from a few different angles. If anywhere, I have sort of narrowed the medial migration (movement of the chain from its centre position towards the centre of the bike) to the front sprocket or thereabouts.

I was wondering what the cause could be and this post is making me consider the swing arm bearings and maybe the wheel bearings too...

Sorry to jump on someone else's thread, but I wonder (or is there any advice about) what else I should be looking for?

[tkent02]

The sprockets look fine (and looked fine when the chain only was replaced last), but there is definitely a tight spot in my chain when I spin the wheel.

The sprockets are worn, and will wear a new chain very rapidly. Again.

[Big Rich]

Chris, a 4.0*18 tire is close to 100/90. But you need your rim width that should be stamped on the wheel. Pretty sure the E models are 1.85" wide, so a 90/90-18 should be perfect.

[JEEPRUSTY]

Thanks for the advice. The bike currently has ~13,500 miles. I have service records showing it was ridden ~10,300 miles by 1984, then pretty much sat until I bought it in 2009 with 11,600 miles.


The rear tire on the bike now is a 4.0-18. What is the equivalent of a metric tire? I was thinking a 120/90r18 might work... I found a dunlop 404 at a local shop in that size.

What kind of wheel bearings are good to use? I saw a $10 kit on ebay for front bearings...

If possible get the specification for your bearings and look to a local industrial supplier. You can high quality bearings for far les than OEM.
I do not think I could trust a ten dollar part in such a critical application.

And is the chain worn out kinked and rusted? Or is it just old? If it is an O-ring that was stored properly it should be good after such low miles on a small cc bike. Chains dont die they are murdered.

[Jagir]

The sprockets are worn, and will wear a new chain very rapidly. Again.

I will be replacing both and the chain this time, but I obviously don't want it to happen again. I suppose my question is about diagnosing the reason why my chain looks to moving towards the middle of the bike (<1/4") when I spin the wheel and watch the chain in relation to the centrestand or swingarm. Could worn sprockets cause this or does it sound more like a bearing issue?

I suppose it doesn't matter. When I have it all apart I should just check or replace the bearings. Is there a way to check them or should I just get new ones? The bike is thirty-something.

[cowboyup3371]

You can check by spinning the tire on your hand or the axle. If it sounds like sandpaper than it's time to replace. Or you can just do it anyway so you know what you have without a doubt.

[pete]

I'd spin it, and not look at the chain or sprocket. Look at the rim and make sure it's running true.

Then, look at the countershaft sprocket and make sure it's running true.

Worse case I can think is a bent countershaft in the transmission, but I think you'd know about that from oil leaks and things in that area.

The other thing I guess is to take random measurements of the radius of both your sprockets all the way around the circumference, which should tell you if one bit is smaller than another and therefore causing what you're describing.

If it was me, I'd be identifying the cause before outlaying more $$$ just in case...

[herostar]

So I went to the dealership and had a good talk with the parts guy that always helps me. I ended up ordering an OEM front bearing kit (~$12), rear sprocket hardware, and a Dunlop 404 for the rear to match the front. The shop does 1/2 price on the tires if you have them do the install...

The guy gave me some ideas what to look for on the chain... When I pull on the part of the chain that's wrapped around the rear sprocket, it come's off the sprocket ~3/8". It appears to be original to the bike, and a bit rusted, so I'm going to need to replace the chain/sprockets.

Regarding the rear bearings... The service parts attendant said the same thing you guys did, to check with a local vendor to make them for cheaper than purchasing oem. I don't have the specs at hand right now, but I do remember that there were three bearings he recommended totalling $45 for oem.