Yamaha parts has a listing for the chain length if you call a dealer, but it is wrong. I am not totally sure exactly the measurement they have listed but it is around 6 or 8 inches short. There are plate chain master links available and engine platforms in the past that have utilized them without issue. Main problem is improper installation of the link which causes chain failure. I know where to get the links but am not really willing to reveal the source. As far as length.. count the links of the original chain. Chain stretch is normally seen as pin wear on the links. When engines get old or suffer a broken cam, it is advised to change the chain. Stretched chains and worn guides directly lead to poor performance and lack of cam duration. I strongly recommend replacing the chain the right way by splitting the case. It is not a tough job to do. Once all the bolts are removed and correct placement noted for re-install, the only real tricky part is to totally split the cases and to remove the starter and alternator sprag and idler pivot pins to release the 2 case halves from each other. Their drive chains will not allow the cases to be split far enough apart to lift the crankshaft up and allow timing chain removal and install. Next fails are during reassembly. Number one is so called back yard mechanics assembling the cases using regular silicone instead of the required Yamabond, Hondabond or the substitute called Unibond. Excessive application (only a few millimeter bead is recommended) plus applying it within 3 millimeters of the crankshaft on the cases will lead t0 crank failure. Not lubing the crank journals during install of case halves is another fail often seen. Next is failure of improper ring placement or lack of help while slipping the cylinder over the pistons and snagging a ring (easy to do) or not having the ring ends placed properly.
Whatever you do, do it wisely or have someone with experience do it right. Example is recently I had a local top runner throw a used chain into an engine, in a pinch while pushed for time. I did it against my recommendation (also before and after my good friend Ken Joyce warned me of the consequences, LOL ). The motor ran real strong and won a two day affair here, but failed shortly thereafter which I knew it would. And of coarse, because of the failure for installing a used chain like I was told to do.... I am getting stiffed on payment of the overhaul (Imagine that...)
I must say, do it right and install the factory new chain don't try to fix it with a band-aid. If you were close to me, I would install it for you for 2 or 3 hundred bucks plus the cost of the chain...
~Gimpster~
