Time for a bit of doohickey musing!
Consider, a) cam chain tensioner, and b) balancer chain tensioner system ("doohickey").
For, a), the automatic cam chain tensioner tensions the chain (countermeasure to chain stretch and sprocket wear) by spring pressure, slack removed in increments, tension held by ratchet notches.
For, b), the doohickey (idler shaft lever) tensions the balancer chain by torquing the eccentrically-mounted idler shaft, ONLY while the doohickey hold-down bolt is eased; thereafter, tension is held by torquing down the hold-down bolt (NOT by spring tension). The doohickey spring only operates during adjustment; in operation, balancer chain tension is held by a snugged hold-down bolt (NOT by spring tension).
Now, consider a-1), a MANUAL cam chain tensioner. Chain slack is removed only when the shaft hold-down bolt is loosened, and the shaft pressed manually toward the roller (NOT automatically by spring pressure, as in a)); tension is then held by tightening the hold-down bolt.
Kawasaki COULD have designed a manual balancer chain tension adjustment mechanism, seems to me, without any stinkin' spring. Even with spring tension to remove balancer chain slack, a RATCHETING system could have been developed to hold the tension, as with the automatic cam chain tensioner discussed in a) above. But, no obvious effort is known regarding any Kawasaki effort toward developing alternative balancer chain tension adjustment schemes mentioned.
So, grenaded doohickey (idler shaft lever) on Generation 1s could result in catastrophic damage. Spring breakage in either generation could result in serious engine damage, as the engine ingests spring fragments. For Generation 2s, loss of spring tension could result in excessive chain slack and consequent vibration, to the point of malfunction; balancer lever failure unlikely from the part upgrade discussed in posts above.
So, what's a poor KLR owner to do? Doohickey replacement (with upgraded part) remains sound maintenance for Generation 1s, IMHO. Hardens Generation 2 durability, as well. An aftermarket "torsion spring" replacing the coil OEM spring comprises a superior design across the generations.
All this said, the OEM KLR owner dances upon a scaffold of PROBABILITY. Some untouched, stock doohickeys never fail over the life cycle of a KLR; some fail early on, with drastic consequences. With a functional doohickey on a high-mileage KLR, Bayesian Probability suggests subsequent failure unlikely. The, "ticking time bomb," certain doohickey failure expectation, appears an over-reach, to me. A rhetorical question: How many, or what percentage, of KLR650s over 30 years of production and worldwide distribution have aftermarket doohickeys installed? (No complete data available, rhetorical question only.)
So, yer pays yer money and yer takes yer choice!
Full disclosure: Eagle Mike doohickey and torsion spring installed on my Generation 1.
(My perceptions only; corrections and clarifications, as always, welcomed!