idle rpm (neutral) -vs- idle rpm (in gear)

[spete]

I have a 98 yamaha 115 hp and it is currently idling at 1000-1050 out of gear and between 700-800 in gear. My question is ... can the idle rpm in neutral be adjusted down without affecting the idle speed in gear? Can they be adjusted separately? The book indicates that neutral should be 700-800 and in gear idle at 600-700. Also, i tested it yesterday on the water (lake temp mid/upper 50's) and ran it for 15-20 minutes ... would the colder water temps keep the idle up? If I adjust down in cold weather will it be too low in warm weather/warm water?<br />PART 2<br />My motor is equiped with a four blade prop and it has great power out of the hole and will spin the maximum recommended 5500 rpm's ... is this bad and should i add more pitch to get more top end speed and work the motor at lower rpms?<br /><br />Thanks for all feedback

 

[rickdb1boat]

Re: idle rpm (neutral) -vs- idle rpm (in gear)

spete <br />The idle adjustment affects both the Neutral and in gear RPM's. Adjusting it in gear is the proper way to do it. Cold water temps with have a small effect on the running and idle, although this should not be a significant problem. You can always re-adjust it in the summer if needed. It sounds pretty close right now. I would stay with the prop set-up you have now, as the WOT RPM's are good and your hole shot is fine. You may lose your hole shot if you prop for more speed and there's no guarantee that you will gain much anyway.

 

[spete]

Re: idle rpm (neutral) -vs- idle rpm (in gear)

thanks rick - just wondering if i punch it and the engine spins 5500 rpm is that potentially hurting the motor (pushing the envelope) or is it designed to operate that high at the specd top end range? Could the engine actually take several hundred more rpm's before "red lining" occurs ? <br /><br />Also, if the difference between my idle in gear and in neutral is 300 rpm and the difference in the book is 100 rpm is that indicating a problem?<br /><br />Thx

 

[rickdb1boat]

Re: idle rpm (neutral) -vs- idle rpm (in gear)

Actually, your engine will take more RPM's than the recommended 5500, but running it long term above 5500 will reduce the longevity of the engine. In other words, you can safely run at the Maximum RPM's with no adverse affects and in short bursts somewhat above that with no ill effects. As for the idle, if it's 800 in gear and 1000 out, it's pretty close. I would set it at 650+- in gear. This will create less drivetrain wear when shifting into gear and will give you a more pleasant idle speed in neutral.

 

[spete]

Re: idle rpm (neutral) -vs- idle rpm (in gear)

Sounds good - will have to bump it down a bit and see how she runs. Thanks for the imput.