Chain Tension

[oddfellow]

Bear with me if this is a stupid question but as I have mentioned before this is my first experience performing my own maintenance. I adjusted and lubed my chain a couple of days ago and after about 100 miles decided to check it and it was very tight. I rotated the wheel to find it loosened as it rotated. I read on one of the posts to adjust it at the tightest point (the manual doesn't make that point) so I did. My question now is how much difference should there be between the tightest a loosest points? I have about a 20mm difference which seems like a lot since the book calls for a deflection of 15mm to 20mm in the first place. Also when checking is the deflection the movement from the top of the chain when slack to the top of the chain when pressed? The manual seems to show the lines marked at the bottom and then the top which would only allow the chain to move about 10mm since it is about 10mm thick. Thanks again for all the help guys.

[psyguy]

that sounds like too much difference in tension (when rotating the wheel)
perhaps your sprocket(s) are misaligned / bent / out of shape (not perfectly round)?

[Nessism]

Your chain is worn out. There shouldn't be any difference in tension as the wheel turns. If you are tight on cash and must ride the bike, adjust the tension so you have slack at the chains tightest point.

[SqDancerLynn1]

Needs a new chain!! Don't forget You need to replace the sprockets too!!!!
Save your money DON'T skimp on a cheap chain

[oddfellow]

Thanks for the advice. I was afraid the chain was fried. Is it normal for a chain to go in 6300 miles on a 400cc bike? I had a 750 magna that had about 20k miles on the chain and it was still good when I sold the bike. It did sit for 20 or so years but that doesn't stress the chain.

[oddfellow]

where to buy?

any advice on where to get a new chain and sproket set online or should I just head to the local shop?

[Nessism]

http://www.z1enterprises.com/

[tkent02]

Is it normal for a chain to go in 6300 miles on a 400cc bike?

Chains were not very good in the old days, and some people never oil anything.

Modern high quality chains will last a long time if taken care of. Do both sprockets, too.

[oddfellow]

sprockets

Thanks for the advice. Do I really need to replace the sprockets as well even thought the mileage is low. Don't get me wrong, I want to do what's best and it's not the money end even though I am a cheapo. It's that I can't stand to waste excessively. I can understand the chain wearing if not properly maintained in 6k miles but do sprockets wear that quickly?

And if it's not too much trouble for one/some of you to explain, what exactly happens to the sprockets? I know (not really but have heard) that the chain stretches which is why it wears out and I can understand how a loose/tight chain could bend or break a tooth on a sprocket but it doesn't look like a sprocket should experience as much wear as a chain or even close to it.

Lastly, if I am going to have to replace the sprockets what size (teeth number) should I go with? (1977 GS400) I don't race and probably won't be doing much touring on it. Just commuting with some interstate running and the Sunday morning sporty run down the backroads.

[80GS750]

my chain has over an inch of slack in it..... its more than a little worn out.. i need to replace it and both sprockets but it will be next spring if at all.... she may be sold before i get a chance.....

i can tell she is pretty stretched out. i think its the original chain and i have 20k on the bike. it has lasted a long time.

[derwood]

Ch Ch Ch Chain

Your chain is stretched in one spot, possibly from adjusting it too tight.
On my old 400 the chain tightened as the suspension compressed so if I adjusted the chain to the right slack while on the centerstand (like suzuki tells you to)it was too tight when bike was on the ground. It only got tighter as the suspension compressed and stretched the chain between the sprockets. The distance between the sprockets changes as the wheel goes up and down so adjust your chain when the sprockets as close together practically possible.
dave

[tkent02]

If you put a new chain on worn sprockets, it won't last as long as it otherwise would. Chains don't really stretch like a rubber band, they wear inside so as the clearances between the pins and rollers get larger the distance between links gets longer, actually the chain has gotten longer.
If you can pull the chain away from the rear sprocket in the back it has worn longer. A good chain on new sprockets you can't pull the chain away from the back of the sprocket even if the chain adjustment is quite loose.
Now when the bike runs, all the power is going through one tooth at a time right as it leaves the rear sprocket instead of a nice smooth pull all the way around, like a little impact or shock as each tooth in turn takes the load. This wears the sprocket into a slightly different shape, the valleys get wider. Because of this wear the new replacement chain won't fit the sprocket quite right, it fits a little loosely even when it is brand new. Now it does the same thing and takes all the load one tooth at a time as it leaves the sprocket instead of the nice smooth pull around. Again it takes more little shocks each time around and makes more heat than it would on new sprockets, it just wears out sooner.
The same thing is happening on the front sprocket too, it is getting worn.

Your first post stated that the chain was getting looser and tighter as it goes around, a sure sign that both are somewhat worn and all three should be replaced.
If you replace only the chain, it will work but may last about half as long as it would on new sprockets, depending on how much wear you have.

Make sure there is enough slack that it never gets tight even at full suspension travel, it can hurt the chain and it is also hard on bearings, etc.
The slack measurement in the manual should be OK for this unless you have altered something.

The stock ratios are a fairly good compromise, probably work out OK for all around riding. It all depends on what you like.

[oddfellow]

Thanks guys. Looks like I'm ordering a new chain/sprocket set in the morning. Valve adjustments are next on my checklist so I am sure I will be back soon.

[Chuckster]

Bear with me if this is a stupid question but as I have mentioned before this is my first experience performing my own maintenance. I adjusted and lubed my chain a couple of days ago and after about 100 miles decided to check it and it was very tight. I rotated the wheel to find it loosened as it rotated. I read on one of the posts to adjust it at the tightest point (the manual doesn't make that point) so I did. My question now is how much difference should there be between the tightest a loosest points? I have about a 20mm difference which seems like a lot since the book calls for a deflection of 15mm to 20mm in the first place. Also when checking is the deflection the movement from the top of the chain when slack to the top of the chain when pressed? The manual seems to show the lines marked at the bottom and then the top which would only allow the chain to move about 10mm since it is about 10mm thick. Thanks again for all the help guys.

Does anyone have an answer for Oddfellow's original question? I have the same question and didn't want to start a whole new thread on the same topic. - Chuck

[Mark whiz]

Chuck,

Personally, when I adjust my chain, I pull it down (taking out all the slack) and then measure the difference from that point to the highest point I can lift up on that particular link. This has worked well for me over the last 130,000 miles on 2 different bikes.