25 Yamaha 2-Stroke Problems

[duckbuckhunter36]

Motor is 25 Yamaha SJ series (1986). Ran great last year on the water, this year it has given me some major headaches. I launched the boat, ran down the canal for about 3-5 minutes and motor slowly starts tapering down until it dies. When started again, it rev's up to max RPM. This has happened 3 times, 3 different trips. I brought it to be fixed, and was told the needle in carb was stuck. The last time, I said screw it, started it in gear, and it took off, but didn't sound like it was running to the fullest of its capability. Any help, ideas or guidance would greatly be appreciated.

[swamp snorkler]

did the mechanic rebuild the carb?

That's a good motor you have, i use to run an 87' 30hp yamaha, i got the carbs rebuilt and you would have though you were running a 60

[budndawn]

Definitely carbs need cleaning or rebuilding

[huntin fool]

Sounds like carb probs. pull them and clean them real well. Get you a can of Power Tune to clean with. Try to run ethonol free gas in it as much as possible

[duckbuckhunter36]

Mechanic didn't rebuild it, pulled it and cleaned it, only to have the same issues again. He said that the insides were worn. I have been running some ethanol gas in it, but have now switched to ethanol free only. Thanks guys for responses, come hell or high water, i am going to figure this one out. It has been a great motor to this point.

[swamp snorkler]

I don't know how you can "wear out" a carb. Maybe buy a rebuild kit for it or a new carb.

Ethanol will be more problems with your fuel lines, however manufacturers now make ethanol friendly fuel lines.

[wtretrievers]

Try changing the needle valves. Most have a rubber tip, ethanol will cause the rubber to swell & give you problems.

[duckbuckhunter36]

I just purchased a rebuild kit, and am now looking for ethanol hoses for this make and model motor. Anyone know where I might be able to find them? Motor issues will definitely test a person's patience. Also, on the motor, it says run 100:1, which i've been told that i should be running 50:1. Obviously I run what the motor says, but trying to rule this out as a contributing factor.

[huntin fool]

I run 100:1 on a new 25 Yamaha, with no problems.
Just did a gasket kit on my carbs, ethonol got to it pretty good. Switched to non, been running fine

[Shallow Runner]

You can find ethanol fuel line at any auto parts store. You can buy outboard connections and a bubble at any marine parts store.