25hp 2 stroke merc, Carb adjustment

[captenc]

Hi, im new to the board! 1st post! my problem is i have 25hp merc 2 stroke, not sure of the year some where around the mid 90's. The motor has set up for a few years, just got it going again back in Dec. The engine runs good at high RPM, but at low RPM she runs rough lot of smoke, and unburnt gas spiting out of the exhaust. The motor is hard to start from a cold start, i have changed the plugs, but still same result. I think the needle valve needs to be adjusted just not sure about how to do it. any help with my problem will be greatly appreciated! thanks!

 

[Laddies]

Re: 25hp 2 stroke merc, Carb adjustment

It sounds like the carb is flooding probably a stuck or dirty inlet needle, try cleaning the carb

 

[andy6374]

Re: 25hp 2 stroke merc, Carb adjustment

If it has sat up for a few years your carbs are gummed up and a carb cleaning is in order. Make sure the fuel lines and primer bulb are okay as well, they don't like varnish.<br /><br />While your at it this winter replace the waterpump and tstat, then enjoy the motor all spring/summer/fall long.<br /><br />Good luck

 

[kalpakis]

Re: 25hp 2 stroke merc, Carb adjustment

Hi <br />I just changed the carb on my early 90's merc 20hp for a 25hp carb.<br />I'm handy but never thought it would be so easy,I ran it in a barrel and everything is fine .I was told not to adjust anything except to match up the throttle linkange from my 20hp . So I switched them and nothing else. (if my termanology is correct).Is there any suggestion on what I can watch out for.<br />Greg

 

[andy6374]

Re: 25hp 2 stroke merc, Carb adjustment

captenc, I don't want your thread to get taken over here so sorry...<br /><br />kalpakis-<br />Engines are designed to run at a specific fuel/air ratio. Do you know what is different about the 25hp carb, like larger jets (probably not that much bigger if they are)? I don't forsee any major problems. Take it out for a good ride at WOT, then immediately (without idling) take a look at the plugs and this will tell you if you're running too rich or whatever.

 

[kalpakis]

Re: 25hp 2 stroke merc, Carb adjustment

Hi<br />Thank you for that.<br />I took it out today and it waaas tough to start. Once I got it going it ran very well and then when I let it sit for an hour it was tough to start again but not as bad as in the morning. I will check the plugs in the morning. I had a mishap today and the engine ended up underwater for no more then 10 min. Saltwater,it was not running when it went under and I have only taken of the cowling and layed it down to dry. I'm so upset with myself. What should I do ?<br />Thanks Greg

 

[andy6374]

Re: 25hp 2 stroke merc, Carb adjustment

captenc- <br />Once again sorry for the hijacked thread.<br /><br />kalpakis-<br />10 min, 30 min, 2 hours...no difference. If you didn't have the time to deal with the engine at the time being it would have been better to keep it submerged. Now that it has sat for 24 hours...<br />It's probably too late!!!<br />It's probably seized , or close to it.<br />You should have gotten it to run right away. This would have flushed all the saltwater out of the system.<br /><br />I would go to the engine, spray some oil down the cylinders and see if you can turn the flywheel by hand. Maybe you can get it started, but a lot of damage is already done. Lets see what other's have to say.

 

[kalpakis]

Re: 25hp 2 stroke merc, Carb adjustment

Kalpakis-<br />Hi Captenc<br />What do u mean by thread?<br /><br />As for my engine ,I put oil in the cylinders and then slowly turned the flywheel.Everything was smooth.I then pulled the start cord slowly and made sure that it was well lubed and sounds great.<br />I put the cleaned sparks back in and got it started but as I mentioned yesterday it was tough to start since I put the newer carb on. It wont shift into forward and run it stops.<br />What do u think? <br />I thank u for your advice and look forward to you response.<br />Thank you <br />Kalpakis

 

[Silvertip]

Re: 25hp 2 stroke merc, Carb adjustment

Kal - You posted your question about you engine in the middle of series of responses to someone elses problem. Start a new "thread" for your problem. Look for the POST NEW TOPIC button to state your question. It's very confusing to try and figure out to respond to when questions come from two or more people.

 

[kalpakis]

Re: 25hp 2 stroke merc, Carb adjustment

Hi <br />Thank you for the advice and I posted a new topic.<br />It is under Merc 25hp starting problems.<br />Thanks <br />Kalpakis

 

[johnevinrude]

Re: 25hp 2 stroke merc, Carb adjustment

clean out the gas tank really good and check the screen in the tank gas line.in just one yaer or left in the rain it gets water in tanks ,you wouldnt think so .but they do.