For your clutch to work correctly, it needs to have the right amount of play at the cable. If you have too little slack, the clutch plates won’t be fully squeezed together when the lever is out and you’re going to get clutch slip, which will quickly lead to glazed plates that’ll need to be replaced. Too much slack and the clutch won’t fully disengage when you pull the lever, which will make it difficult to shift and the bike may creep at stops when the transmission is in gear.
To check your free play, the engine needs to be cold since hot clutch plates will expand a bit and throw off the measurement. Usually, you check the play at the end of the lever or between the back of the lever and the perch, but you’ll want to reference your manual for the exact specifications and measurement protocol for your bike. In general, 3-4mm at the perch is a good goal, and as a rule, it’s always better to have too much slack than too little.
If you need to make an adjustment, there are two places to do it. You use the barrel at the lever to make minor day-to-day adjustments, or you can turn the locknuts down at the engine to make larger changes. Try working with the barrel first, and if you can’t get the right amount of slack, screw it all the way into the perch and then turn the locknuts down at the engine to bring the free play into spec. Keep in mind that for maximum leverage and ease of use, you want to maintain an 80- to a 90-degree angle between the clutch arm and the cable.