got my 75 sporty on a stand when i roll the rear tire the chain loosens and as i keep rolling the tire it will tighten. the rear sprocket and drum and brakes are new and the allignment seems to be good and the swing arm is not loose. has anybody seen this before?

 

Is it dry? it sounds like its dry and the links binding. If it is dry lube it. Also, how old is it? it may be shot.

 

how old is it? how many miles on the chain? a chain does not stretch evenly, to adjust set the chain at the tightest point , you say the rear sprocket is new , what about the front? they need to be replaced in sets ill bet the chain is stretched and it isnt matching the new sprocket if this is the case you need to replace all 3 pcs at the same time, you will wear out that new sprocket in no time

 

i suspected it could be the chain, it is old. it is an o-ring chain, i ran these on my dirtbikes and they seem to last forever. i do keep it lubed but i'll take it off and check it out along with a new front sprocket. thanks

 

It is typical of a worn chain to have tight spots and loose spots. This is the way they wear. Follow the instructions in the factory service manual - adjust the chain at its tightest point.

Then rotate the loosest part to the back of the rear sprocket and try to pull it off with two fingers. If more than 1/2 tooth is exposed the chain is no good.

With the chain adjusted at its tightest point, if the loose part bangs around in the sprocket cover area, chain guard, whatever, then it is no good.

 

it all and how hard you ride and how much you ride,i ride a good bit, i have ran expensive chains and get maybe 2 years, now i just run a nickel plated basic chain, change it every season sprockets whenever they start wearing

 

As others have said this is due to a worn chain.
The chain may be already worn out.
You can remove the chain and stretch it out on the driveway.
Push each link together toward one end.
Then mark the concrete at each end of the chain.

Holding one end of the chain (you may want a helper) grab the opposite end and pull out to extend the chain.
Where is this end relative to the pencil mark?
If it shows more that a half link of difference, you need to buy a new chain.
A worn chain will eat the sprocket teeth alive once it wears enough.
And if you have just installed new sprockets YOU DO NEED TO INSTALL A NEW CHAIN............ Now.
pg

 

i was installing the new rear sprocket when i noticed the problem. i put a new o-ring chain on today it made a huge difference but the bike isnt going to move until the new front sprocket is on.before i started riding last year i put new rings in it and took the heads to a local shop they ported and polished them and installed stainless 2" intake and 1 3/4" exhaust valves bronze guides new springs and seals on the intake valves add that to the s&s stroker kit and super E carb makes it hard not to run it hard every now and then. i put a little over 3000 miles on it last year so i guess that was the demise of the sprockets and chain. thanks for the feedback. i thought o-ring chains were indestructable i guess i dont know it all ,just ask my wife!!

 

Absolutely! Do not run the bike until the new front sprocket is installed.
The O ring chain is a good choice for a chain but all chains wear.
When running, the chain is as straight as a steel rod on top but when it comes around the front sprocket it becomes loose and whips up and down.
Both positions wear the chain. Each separate link is stretched a tiny amount. You cannot measure this until enough wear has occurred where you lay it out as I described and see the total wear. By then of course the chain needs replacing.
pg

 

Back when I had the chain drive bikes and if I changed the sprocket or chain I changed both sprockets and chain as a set. I went to a industrial shop that sold chains for the big conveyor belts and like and bought 50 chain.