i was riding the other day and my 686 would not start. i noticed it was spinning over real easy but could not tell what the problem was. i got it home and noticed i had spark and fuel so i started tearing in deeper. i realized my cam and valves were not moving when i turned it over. i opened up the side cap and my timing chain was extremely loose. i hope that the chain is broke and nothing else. i will tear it apart this weekend and see if their is any more damage. do you guys normally replace the chain when doing a 686 and if so is there a stronger then stock one available. i have had a ton of problem i beleive is related to the 686 kit but over all the power increase is well worth it.

 

the stock chain should be strong enough to turn the cam, unless you get some outregously stiff valve springs! hope it was just a fluke and nothing major!!

 

I have been wondering about the timing chain as well. When buying engine parts off of ebay, I see that that they are parting out the engine because of a timing chain failure. I have seen this alot. I bought a used cylinder and the timing chain cavity was all torn up. It looks like it had timing chain failure as well.

I checked mine over an it looked good before I put my 686 together. At least, nothing jumped out at me.

What I think (hope) happens is that people install the big bolt into the tensioner before tightening the bolts that hold the tensioner to the cylinder. This will overtighten the chain and cause it to fail.

I hope it is something like that.

 

mine ran for a year before having this problem. hopefully it is a fluke and nothing common.

 

I would replace with any build you do, its a few dollars and does get streched over time causing it to fail..

 

Last time I checked it was more than a few bucks, more like 60. If someone knows where to get it cheaper let me know.

 

Ever priced a complete head, new valves, rockers, port work, maybe even the piston and cyl? Compared to $60 its a lot.

 

The 01 timing chain is around $60. Yamaha changed suppliers for 02 up, and they are around $25. Most failures are related too installing the tensioner incorrect.
Gary

 

Thats for sure ward, and a few bucks now is better than a bundle later. That's why I have waited to bump my displacement and compression until I can afford a new rod as well. I was just trying to say that it wasnt just a cheap little item that you buy a few of and keep around like some gaskets or jets, etc. But I didnt know the new ones were only 25 bucks. There really isnt a reason not to change it when you do major engine work for that kind of price. I might change the chain the next time I adjust my valves.

 

$55-$60 is nothing when you do a 2-5k build. [img]i/expressions/face-icon-small-shocked.gif[/img]