2001 25 4 stroke yamaha

Toulla

Cadet
Joined
Jul 8, 2007
Messages
14
new to the site :
2001 25 hp 4 stroke yamie.
240 hours on it.

After about 50 hours a funny noise, detectable to me but no else developed deep in the power head. Took it back to the dealer, lucky for me a yamaha tech stoped by, listened to the engine and came to the conglusion that the crank shaft was out of balance. new power head(Only) was insatlled. Went through brak in procedure, and had the valves clearance inspected for the 1st and last time.
The engine run well with no problems till 2005 and accumulated 200 hours on it. Then I had to put her in storage for about a year.All fluids were changed and the carburator drained. I have been ysing ring free religiously after the brake in period.

Now, the problem I am having with it is it starts, and runs good, yet I hear a noise that I equate to an old car engine with loose valves. I asked the dealer to check the valve adjustment and he said " we check them all the time and they are never out of adjustment." I don't know about that but hey, he is the expert.

In addition, after about an hour or so of running time she gets noisy, like a tractor, it's like it a different engine all together. She does not loose power, she is just not as smooth as she is NOISY. Even in neutral if i give it gas I hear the ratling noise( pinging noise.) I t is just strange.

I always run new gas, with ring free in it. The last couple of times I run her with out it just to see if that is my problem, no it does not seem likely.
I want to find out what I need to do to get her to be quiet and smooth again. I do troll her a bit but never for more than an hour before I get her going again.

Also what is poppet valve, and should I replace the water pump even though it seems fine, no cooling problems, no waterflow problems. I do flush her every time after use religiously.

I didn't see other 25s on the water, and even on this site not too many comments about this engine. Except fuel and carb issues, which I don't have yet.

Any comment on the procedure of ajusting the valves would help as well. Thank you to all
 

JUSTINTIME

Captain
Joined
Sep 2, 2006
Messages
3,284
Re: 2001 25 4 stroke yamaha

poppet valve is the water pressure relief valve
when you go above 2000RPM it relieves the water pressure in the block

if that motor has an o2 sensor that would make a valve tapping sound
 
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