How Tight Should the Chain Be On A New Bike? | ANSWERS

Q: I bought a new Yamaha FZ-09 recently, and when I took delivery of it, the chain was as tight as a banjo string. I've since traded it off (I'm sorry I did), and I'm now waiting for a new red FJ-09. The local dealer just got a matte gray one in, and I had a look at the chain—it, too, is banjo-string tight. Is this a new thing with the factory, or is the dealer not setting up the bikes right?

Greg Springfield
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A: It's temping to think the dealer is screwing this up, but if you take a look at the owner's manual for the FZ-09 and FJ-09, they both list a chain slack specification of a scant 5–15mm. So the dealer is in the right even if it doesn't "look" correct.

The question is why does Yamaha spec the FZ-09's (and FJ-09's) chain tension so tight? We asked our Yamaha reps that very question and received an answer similar to what's in the owner's manual. If you run the chain any looser than 25mm of slack—at the mid lower run with the bike on the sidestand—it could hit the frame.

Curious to know more, we placed our FJ-09 testbike on the lift and compressed the rear suspension. In our view, there’s no way the chain can come into contact with any part of the frame. Moreover, when we started the experiment with 30mm of slack, the chain had just 10mm of free play with the suspension compressed, which, in our interpretation, means that using the factory-recommended setting will result in no slack with the suspension compressed.

Normally we’d strongly advise adherence to factory recommendations. Not this time. For whatever reason, Yamaha has called for a chain spec that, we feel, will result in a chain with little to no slack in actual use. That’s bad for chain-drive bikes—hard on the chain, sprockets, and even the countershaft seal and bearings—and we’d never subject one of our own motorcycles to such treatment.