1980 50hp evinrude rattle

[bdirect]

Thanks to everyone here at the forum i have had a great summer/fall with my boat . This 50 had not run for 5 years thanks to all the advice here it ran great except for one issue that started 2 weeks ago. Sometimes at WOT there is a rattle noise . It is not all the time and I can not tell exactly where it is coming from. If this was a car i would say valves or timing a little off but don't know enough about 2 stroke outboards to help myself. Any ideas ?

 

[DJ]

Re: 1980 50hp evinrude rattle

bdirect,<br /><br />Have a look at the spark plugs. Do they look the same?<br /><br />Are there any shiny objects attached to the plugs?<br /><br />Check the compression and post the results.

 

[bdirect]

Re: 1980 50hp evinrude rattle

DJ<br /><br />When i pulled the plugs both were clean except for normal (i have been told normal) bit of oily sheen to them

 

[bdirect]

Re: 1980 50hp evinrude rattle

OOPS compresion was (if I remeber correctly) 100 both cylinders

 

[DJ]

Re: 1980 50hp evinrude rattle

That's all good!<br /><br />Have you ever decarbed it?<br /><br />See description below.<br /><br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000016

 

[DJ]

Re: 1980 50hp evinrude rattle

bdirect,<br /><br />More thoughts.<br /><br />Are you doing anything different, I mean pulling back on the throttle differently?<br /><br />Also, check to see that the timer base (under flywheel) moves freely with the throttle. You can check this with the engine NOT RUNNING.<br /><br />Keep us posted.

 

[bdirect]

Re: 1980 50hp evinrude rattle

DJ I checked the flywheek timing looks good.<br />No i have not de-carbed purly out of fear that with an older engine I may loosen something up that carbon is keeping tight. Now being a newbie at this I will not hold it against anybody if they believe it realy should be done even on an older engine . <br />More reading today and wounder about the reeds?

 

[DJ]

Re: 1980 50hp evinrude rattle

bdirect,<br /><br />Decarb it. Carbon is the nemisis of two stroke engines. It "holding things tight" is exactly what causes pistons to score and cylinders to be ruined.<br /><br />Trust me, you WILL NOT hurt it. You will probably be amazed at how much better it runs.<br /><br />The reeds will not cause what you are describing. A bad reed may make it "sneeze" at idle. You would notice by having blow by coming out of the front of one of the carbs.

 

[bdirect]

Re: 1980 50hp evinrude rattle

DJ <br />I am going to decarb this weekend and then see if it makes a difference. I do troll a lot 3knts for hours on end and even though I run at WOT back home who knows how much stuff is built up in there at this point

 

[DJ]

Re: 1980 50hp evinrude rattle

Keep us posted. BTW, a decarb may require new spark plugs after all the junk is blown out.<br /><br />Use Champions-ONLY!

 

[fireman57]

Re: 1980 50hp evinrude rattle

trolling will not make it carbon up. Having it not running right is what does it. As DJ says, definitely put in new plugs after decarbing. Get ready for a TON of smoke when you do this. If you do it on the lake get ready for every boat out there to come over to see if you have trouble. If you do it in the driveway the fire department might show up because the neighbors will think you house is on fire.