Yamaha 40 HEO info and questions

[Croatian]

Hello from Croatia,
recently I bought Yamaha 40HP 2 stroke engine for my 4.40m long fishing boat
Engine was stored couple of years and very rarely used
I replaced sparks, filled it with Yamalube and new impeler+new prop
on full throttle it goes around 24-27 mph

my questions are:

- how can I check year of production of this engine?

- what is maximum rpm for it? It never goes above 4100 rpm by looking at the gauge?

- It runs fine but sometimes above 3000rpm I can hear some kinda of ''kkrr'' noise, it starts every 2-3 seconds and repeats, it is very minor I can't even record it (loud old machine ) and when it hits above 4000 rpm it sounds like choking, wont go above.

Idles perfect, starts perfect, consumption fine etc
I just want it to be perfect as possible

I have couple of vids so please check and opinions
many thanks

https://www.youtube.com/watch?v=mW0SYKdgTW0
https://www.youtube.com/watch?v=hSQWB2B0kJU

[almetelo]

To let you know year of manaufactured we must know the serial number before.

If linkage is correct on you motor so VERY overproped as your motor MUST run at 5500rpm or close at wide open throttle "full throttle", so your motor must have "small pitch and or diameter" proppeller as you can damage the motor on your´re not getting the best of it.

on 1st video motor sound noisy to me...

[Croatian]

To let you know year of manaufactured we must know the serial number before.

If linkage is correct on you motor so VERY overproped as your motor MUST run at 5500rpm or close at wide open throttle "full throttle", so your motor must have "small pitch and or diameter" proppeller as you can damage the motor on your´re not getting the best of it.

on 1st video motor sound noisy to me...

will post picture of manufacturer markings
in fact it's not noisy while driving, you can speak normally onboard which was not the case on friend boats euipped with similar 2 stroke like Mercury etc

I had original prop which was bad, so I replaced it with new one, identical to old one, with both props limiter was 4100 rpm :/
perhaps the gauge is reading incorect?