Better to have it and not need it than the other way around. If you're going to flush the motor oil that's TWO changes.I can't believe the ballers on this thread. A new drain washer!?
Yes, I do know how to correctly change gears on a bike (and in my standard car), but yours is a reasonable question.I would love to listen while the original poster starts off from a stop (particularly if it's uphill), and watch their clutch hand while riding ... just to see whether it's an operator issue, or a vehicle issue.
How's the clutch lever feel? Does it move smoothly, or does it feel grabby and gritty and lurchy? A squirt of lubricant on the pivot point of the lever now and again, works wonders.
Questions for the original poster. Can you, and do you, start off from a stop without the tach needle going past 2000 rpm until your fingers are completely off the clutch lever? Or are you slipping the clutch at high revs for an eternity before the bike starts moving which it then does with an enormous lurch because you haven't gotten a feel for the engagement point? Do you understand what I am talking about, or not?
In my car (manual transmission), I start off from a stop without the engine going above idle speed until my foot is completely off the clutch pedal - next to no slippage. On other vehicles I've gotten 400,000+ km out of original clutches. This one is at 208,000 and counting. Bikes will often do 100k on a clutch unless you are abusing them. If you abuse them, they can be destroyed in 15 minutes.
Having pointed accusations in the direction of the operator ... I recognise that there are some bikes that have two separate adjustments for the clutch release mechanism and they both have to be correct, and if the hidden one down at the bottom that the uninitiated won't know about isn't correct, the clutch will slip and self-destruct in short order. Yamaha FZRs were like that. (I have two of them.) I tend to suspect that the CBR300 clutch release mechanism is more similar to that on the CBR125, and it doesn't have that issue. The part of the release mechanism that is internal is either assembled correctly (and works), or assembled incorrectly (and does not work at all). There's no hidden adjustment. BUT ... I have not personally worked on a CBR300 clutch.
Your closing sentence is my best argument I think.*If* this is just a simple clutch plate replacement he should have no trouble doing the job if he's half decent with repairs. But the way this narrative seems to be playing out, there's something wrong in the assembly, the dealer is overcharging him to cover the cost of the extra parts and they're not telling him because they screwed it up. No clutch goes out that quickly unless there was something very wrong.
Your closing sentence is my best argument I think.