Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

[JSilsbyII]

I have a Tohatsu 25HP 2 cycle that runs rough while idling & at idle speeds. It just started this after about a year & half. I am considering changing plugs and cleaning filter. Anything I need to know about this or other potential causes. I don't think my gas is bad. It is a new tank and a fresh mixture at 100. ???<br />John

 

[ziemann]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

Change plugs like you are planning...then see how it runs. <br /><br />The vast majority of the time here, when these questions are presented, they are due to a dirty carb... Varnish forms easily and causes all kinds of rough running signs and symptoms...

 

[TOHATSU GURU]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

Mix your gas at 50:1....1 pint of oil to 6 gallons of gas.

 

[JSilsbyII]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

Originally posted by INTERNETOUTBOARDS:<br /> Mix your gas at 50:1....1 pint of oil to 6 gallons of gas.

Changed the plugs, 50 to 1 was the break in mixture. Manual recommends 100 to 1.

 

[JSilsbyII]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

Originally posted by John P Silsby:<br /> I have a Tohatsu 25HP 2 cycle that runs rough while idling & at idle speeds. It just started this after about a year & half. I am considering changing plugs and cleaning filter. Anything I need to know about this or other potential causes. I don't think my gas is bad. It is a new tank and a fresh mixture at 100. ???<br />John

Changed the plugs, now it runs like a kitten. Thanks for the input!

 

[TOHATSU GURU]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

Your engine is not supposed to be run at 100:1. It's 25:1 during break-in and 50:1 after break-in. If your manual say's 100:1 its referring to synth oil or its a miss print.

 

[jwilkey84]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

My grandfather has a 60's johnson sea horse that runs great. But we have forgot what the fuel ratio is. If I remember right, it calls for something other than 50:1, but I think someone told me that with the TCW-3 these days, 50:1 is the standard for all two cycle outboards, is this right? Sorry, its for a Johnson, but it just came to mind while I was reading this.

 

[Pogo123]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

On older engines, Thedammit, you would be better off at 25:1. 50:1 is standard, as Elvin says, in the current industry though. Your 60's Johnson will last longer running on the rich side and, though it may smoke a bit and you might foul the plugs a bit faster, it'll run fine.<br /><br />Better to err on the oil rich side than the lean side.

 

[Pogo123]

Re: Tohatsu 25HP 2 cycle runs rough idling & at idle speeds

By the way ... your manual may not be a misprint, but I'll bet there was an addendum circulated which changed the 100:1 to 50:1. <br /><br />Particularly in the mid to late 80s, several manufacturers printed 100:1 in the original manual but corrected them all back to 50:1 by 1990 ... Tohastu/Nissan, Suzuki and Mariner to name three.