...I just watched a video on youtube that I thought was pretty interesting pertaining to the who doohickey subject. (!BEWARE ! Kawasaki KLR 650 , another doohickey video . Part 1.) This one talks about the reason for the spring being loose which was caused by a worn chain which in turn wore out the chain guides. After replacing parts he was able to put the original spring back on showing that it had plenty of
I think he's a bit confused about the mechanics of the problem, though I wouldn't go so far as to say he is wrong.
The chain runs in an oil bath and it doesn't really wear and elongate. It rides on rubber rings that are on the sprockets. As it runs the rubber compresses a bit and that puts slack in the chain.
One of the dangers that are inherent in the system is that, as the chain slackens and runs loose, the chain swings free of the sprockets. That creates wear on the chain guides but the chain can also impact the case, especially as it turns around the sprocket at the upper balancer sprocket.
This is why we say that, especially on Gen 2s with their known-to-be-long spring, one should not adjust the lever without confirming that the spring has the ability to tension and why it is a good idea to perform the adjustment with the engine at TDC. The TDC idea comes from @pdwestman
. FYI, I think Paul has forgotten more about Kawasakis and the KLR than most people know about them.
What the guy did was find evidence of this 'wide running' of the chain, and we already knew that and why it happens. The real fix here is to replace the sprockets, effectively restoring the chain to a shorter length and allowing the stock spring to work again. He never got that far in to see that condition, though. Given the position of that lever, I'd guess that the KLR in the video is quite a high mileage one.
However, it is not really necessary to replace the sprockets to fix the issue. It would be a bit of overkill because the aftermarket lever allows for more adjustment and the torsion spring will continue to allow that to happen after a stock spring has run its course. I believe the chain eventually settles on the sprocket and begins to truly run like a roller chain on an involute sprocket and the need for adjustment diminishes. I can't confirm that with my sample of one yet, and there are not that many KLRs with in excess of 100K miles to get data from and not enough people like watt-man to answer the question definitively. He's well over 100K miles on a stock engine save for the balancer lever and T-Bob. If there were 10 more people like him we might be able to get reliable data.
The development of the balancer lever fix has been evolutionary. At first, the problem was the welded lever on the mid-to-late Gen 1s. Those tended to break and get mixed up in the engine, which was bad. Jake Jakeman fixed that when he came up with the original replacement lever, which he called a 'doohickey'. His idea, primarily after his death, was taken further with an even nicer, better fitting, lever and a kit that included a couple of springs of different lengths so that you could swap in a shorter spring as the system settled in. Ultimately, the torsion spring was conceived and the fix became a one-shot fix-it-and-forget-it rather than an iterative process through the life of the bike.
Kawasaki changed the lever in '08. It was a much better lever, but they coupled it with a longer spring. We don't see broken levers with Gen 2s, but the spring has become an issue. That spring goes coil-bound anywhere from right off the show-room floor to 20K miles, with the most common occurrence, anecdotally, from 5K to 20K miles. Now we have people making the adjustment against a slack spring which puts more slack into the chain than was there before they made the adjustment.
Kawasaki has used four or five different springs over the years. Why they went with a longer spring, and continue to use it to this day, is a mystery that remains in the hallowed halls of KHI.