Hi,
As a rider for over 20 years, I think that you already have 2 very good replies:
I am sorry to say but the engine is going to remain the same and things are not going to change dramatically after the first service. This is a hard revving engine and if you want to remain in 3rd gear while doing 50kmph, then you'll be revving the engine past 4-5k rpm and that is when you will feel that the engine is getting strained, which in reality it is not cuz it does come alive at that rpm. But I know what you mean so I would say that you just need to get used to this engine characteristics. From my experience, you will be able to do 30kmph in 3rd gear at roughly 3k rpm and that is when you will feel that the engine is relaxed. Go beyond 3k rpm and you will feel that the engine is stressed. Again, perhaps you feel like that cuz you're used to riding a more relaxed engine.
But maybe I can still contribute something, since you state that you are a new rider, and there is a bit more to the total picture.
1) Running in
You should run the bike in, as specified in the manual.
This will extend the life of the motor, but will have little effect on it's overall feel. ( I actually did 1,000 miles, not just the specified 750 )
2) This bike is a single cylinder.
This format is inherently unbalanced, since there is only the weight of a single piston being thrown up and down inside the motor- up, stop, down, stop, back up.
Even with balancing weights on the crank to counteract the forces created, it will never be as smooth as an inline twin cylinder, or triple, or the most balanced of all inlines, a
four. In these formats the pistons are timed to rotate in an order to help smooth out vibration by counteracting the weight of one piston with the weight of another.
Other options, like BMW's famous 'Boxer' twin engine have 2 'opposing' cylinders. One cylinder comes out of one side of the engine, and the other on the other side.
The weight of one piston is counteracted by the opposing piston on the other side- Inherently smoother than all the above.
3) High revving engines
As the quote above, with modern lubricants and technology, engines are designed to rev high. It's not a problem !
So, I really think the concept of 'strain' at only halfway through the rev. band is misleading.
The bike is NOT 'straining', it is vibrating ( sure ), and getting nearer to the higher level of power output ( 'coming on cam' ),
That's not doing the bike any harm at all. In fact, it's exhibiting both the designed performance ( more power at higher rev.s ) and the limitations of the motor's format. ( single
cylinder at faster revolutions = more vibration )
I grew up riding 2 stroke 'screamers', which were all about maximum BHP in very narrow power bands at the very top of the rev. range.
That simply meant high rev.s or zero power. Check out reviews of the Kawasaki Mach III H1 from the 70's for the most extreme illustration: 2 choices- power off, power on !
The red line is your guide for the limits of the engine, and as a fail-safe, there is an automatic rev. limiter which just cuts the engine if you go over it.
But that says nothing about your comfort !
If you don't like the feel of the high rev.s, you'll learn how to avoid them.
4) Gears
Gears are primarily designed to maximise the power of the engine to obtain the highest speed possible.
Anyone using a pedal bike knows that to try to start off in top gear is near impossible.
Likewise, you cannot possibly pedal fast enough in a low gear to get to the same speed you can in top gear.
Now, transpose this to the motorcycle, thinking of what you asking your motor to do in each gear.
Now, question: Why do you want to 'cruise' in a low gear ? What are you trying to achieve ?
It seems to be a bit like looking through the wrong end of a telescope. You can do it, sure. But, why would you ?..
If you want the bike to feel 'lazy', choose a higher gear. Less rev.s, less vibration, but less power/slower reactions to the throttle.
Lower gear at the same speed means more rev.s, and it'll feel 'busy' !
I hope some of the above helps.