chain tensioner

Yes, you can't adjust the chain very well, or very much. Sometimes these chains stretch a LOT.

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If it ain't broke, and you mess with it long enough, it will be.

Ive Kept Mine Pretty Tight With Half Links And I Do A Lot Tire Burning For All The 24 Year Old Kids Standing Out Side The Hardware Store When They Ask "how Much Power Does That Thing Make?"

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MEASURE ONCE AND CUT TWICE.......WAIT A MINUTE

Compared to the stock chain tensioner, I have found absolutely no downside to going without the tensioner. In my case, the stock chain seemed to be stretching bad the first 100 miles WITH the stock tensioner but immediately quit as soon as I removed the tensioner. I cannot comment on spring loaded tensioners because I have not tried them.

When I was using the stock tensioner without any mods it was a pain to adjust the chain. After adopting the "T-Shirt" solution posted by MotorbikeMike I found it much simpler to drop in 1/8" shims to dial in the chain length and have not had to adjust it in the 200-300 miles since then. Not only that, but my chain has run quieter and I no longer worry about the chain getting thrown from the sprocket.

Incremental Chain Tensioning, Chain Management

Some guys use nuts, half links, or other stuff for spacers but I found it worth the $3.00 strip of 1/8" flat stock from my friendly neighborhood hardware store and about 5 minutes work with a hacksaw to make the T-Shirts:

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Cheers,
Paul

50cc Slant Head mounted on a $5 Huffy mtn bike
http://www.youtube.com/watch?v=tfN5nW7JIjw