i have a 2001 honda spirit 750.  I have replaced the chain without problems but about every 150 to 200 miles i have to retighten the chain.  Its not difficult but i can't understand why the chain would be stretching this much in such a small amount of time. Any suggestions?
D.I.D brand chain.  
( just bought RK chain  to replace along with new sprockets)  

Did you buy the standard race, or the O-ring version?

Several years ago, I had a non O-ring chain put on, it stretched all the time from the original installation. Then the master link started seizing, and it stretched like taffy.

I put on a good o-ring chain, and after 2000 miles, it only needed about 2 nut faces of tightening. Then the master link started seizing, and  it stretched out the chain and destroyed it in short order.

Either way, I'd find the master link so you can make sure it gets lubed. Clean it, put a dot of bright paint oe nail polishzs on it, let it dry, then lube it.  

O-ring chains retain the grease inside the link axles, until the o-rings fail, which may be as early as 15,000 miles. Until that happens, chain wear (stretch) is almost non-existant. If you change the chain at the first sign of O-ring failure, the sprockets will not be worn and can continue to be used with the new chain.

Old-tech chains (no O-rings) let the grease squeeze out of the link axles in the first 100 miles of use. They immediately start wearing (stretching). As the links wear and lengthen, the chain no longer fits the sprockets, so the sprockets start wearing also. By the time you have a couple thousand miles on the chain, the sprockets are worn enough to ruin a new chain, so when you change the chain you also have to change the sprockets.

Maintenance on an Old-Tech chain...

Getting lube back inside the link axles is not easy. If you do succeed, it will just squeeze back out again. Until it does, the chain will cease to wear and the life of both chain and sprockets will be extended to some extent. There are two ways that I have used to do it.

1) Remove the chain from the bike and submerge it in melted grease. Work the chain back and forth, bending every link, so the hot grease can seep into the link axles. Let the grease cool and congeal before removing the chain. Wipe the excess grease off the outside of the chain and reinstall it.

2) Using a foaming spray chain lube, force grease between all the link side plates, so some of it will expand into the axles. Wipe the excess grease off the outside of the chain. Wait until the grease fully congeals before riding.

Both methods are very messy and your chain will be slinging grease all over the back of the bike and rear wheel as you ride. Neither method will significantly increase chain life, unless you do it at least evey 150 miles. That means you will spend hundreds of manhours trying to get the Old-Tech chain to last 15,000 miles instead of just 10,000 miles and you'll still have to replace both sprockets when you replace the chain.

Personally, I came to the conclusion long ago, that it's better to just spend the $80 on an O-ring chain and replace it when I replace the rear tire. If I put a 20,000 mile tire on the rear, I buy a $120 X-ring chain that will also reliably last 20,000 miles. Then, it just takes a little lube on the chain rollers to prevent early sprocket wear and my sprockets easily last through several chains.

regards,
Joe  

thanks for ur input.