Can you idle a 4 stroke too low?

[dmangi]

I dealer that was really pushing 2 strokes told me if you idle a 4 stroke too low it can hurt it. I would like to know if any of you have heard of that one, or if he was just trying to sell his motor. Thanks.

 

[JB]

Re: Can you idle a 4 stroke too low?

That's bull, Dan.<br /><br />You are more likely to harm a 2 stroke (fouled plugs) by too much slow idling than a 4 stroke.<br /><br />Find another dealer, and good luck.

 

[steam_mill]

Re: Can you idle a 4 stroke too low?

What a load of c$ap.<br /><br />4 strokes are promoted a great idlers.<br /><br />I run 2 stroke but only because they're cheaper and I'm still not convinced on 4 stroke longevity.<br /><br />Will a 7.5 hp honda or merc or yammie or whatever be running in 2054?<br /><br />Well my 'rude 7.5 hp 1954 still runs well....<br /><br />Joe

 

[ED21]

Re: Can you idle a 4 stroke too low?

I have heard the briggs & stratton air cooled outboard may overheat if idled to long. Don't know if it's true. Nothing a wide open run wouldn't cure if it is.

 

[BillP]

Re: Can you idle a 4 stroke too low?

I don't know the answer but have a comment. I have a 50hp 4 stroke with a huge oil fill cap. When removed you can see the entire valve train and how well it gets lubed...and I have checked it several times at idle and used a flashlight to look in. All the parts do NOT get totally splashed or lubed at the lowest speced 650 rpm idle speed. At 150 rpms higher the oil flys everywhere and all parts get a good dousing. I set the speed up and don't worry about it now.

 

[Forktail]

Re: Can you idle a 4 stroke too low?

As long as you've got some oil pressure, you're ok. I have some F115's that idle at 550 RPM for hours on end. F225's at 650 RPM. I idle my T8's and T9.9's down to where they almost stall. They have thousands of trolling hours on them. Some of the newer 2-strokes inject practically zero oil at low idle, so beware.

 

[dmangi]

Re: Can you idle a 4 stroke too low?

I sure learn a lot here! Its hard for me to believe any of the dealers because I dont know if they are just trying to sell their motors or not. I was referring particularly to the Tohatsu 9.8. Another thing he said was that motor was so light because it isn't really 9.8 HP. Isn't rated HP the same no matter what? And to maintain them, is it as simple as a 2 stroke (changing the oil, gear oil, spark plug, and filter) once a year, or does it require more to it than that? At least I can get the facts from you guys! Thanks.

 

[JasonJ]

Re: Can you idle a 4 stroke too low?

I idled the snot out of my old 63 Homelite 55 4 stroke and it never skipped a beat. As with any engine, you just don't want to lug or expect the engine to work too hard at too low of an rpm, that will cause damage. A 4 stroke pushing a boat in gear at idle isn't going to hurt it, but drive a car in fifth gear at 25 mph and you'll kill it for sure.

 

[Forktail]

Re: Can you idle a 4 stroke too low?

Dan, the Tohatsu 9.8 is the smallest displacement engine in it's class. Add to this the fact that it comes standard without a charging system, and you have a very light outboard. <br /><br />All engines this size are HP rated with an allowable ICOMIA manufacturing tolerence of +-10% (at rated speed). This means in reality the engine could actually be measured on a dyno to be a 8.8 HP or a 10.8 HP. My guess is it comes in right around 9.5 HP.<br /><br />As far as maintenence, I don't run Tohatsu's, but my Yamaha 8's and 9.9's require an oil change every 100 hours (after break-in). Takes about 5-10 minutes. No oil mixing or plug changing to worry about. With good maintenenence and storage, chances are you'll get thousands of hours without need for a repair or adjustment.<br /><br />Nice motor. Motorboating's Editor's Choice Award.

 

[dmangi]

Re: Can you idle a 4 stroke too low?

Wow, I'd be lucky to get 30 hours a year out of it trolling. At that pace, it should last me over 30 years before getting it repaired. Haha. Seriously though, is it better to just winterize a motor, or just to start it every month because I'd keep it inside.