Engine running rough at low RPMS & Prop nut size

[Rogue I]

Okay, I have two questions I need your help on. I have a 1997 225 Evinrude that I just fired up after a long winters nap. Changed the plugs w/ new champions (I gapped to 35 but understand they should be at 30 which I will correct this evening).

1) My engine idles fine, runs from 1500rpm-up fine, but kind of runs a bit rough from let's say 1000-1500rpms...just a bit of shaking. Doesnt want to stall, just doesnt feel as smooth. Idles fine in gear at about 650 rpms. What is causing this?

2) I need to change my prop--what size nut holds the prop on? I thought it was a 1" nut or? 13/16 was too small.

I really appreciate your help!

 

[Rogue I]

Re: Engine running rough at low RPMS & Prop nut size

Bump...thanks in advance for your help!

 

[Rogue I]

Re: Engine running rough at low RPMS & Prop nut size

No one can help me?

 

[ezeke]

Re: Engine running rough at low RPMS & Prop nut size

The prop nut is 1-1/16.

 

[Rogue I]

Re: Engine running rough at low RPMS & Prop nut size

Thanks!

Now does anyone have ideas on the rough low rpm issue?

 

[perkdp]

Re: Engine running rough at low RPMS & Prop nut size

I'm a small engine tinkerer, shade tree guy, but since you don't seem to be getting much response, I'll throw this out.......
Most of the small outboards I mess with have a short window when throttling up where it seems a bit rough. I'm thinking there in the range where spark advance, lean idle mixture and high speed jet are all in sort of a conversion stage.

You may one, or more carbs that are a bit clogged, out of sync, or adjustment.

Could be a slight miss-fire on your incorrectly gapped plugs.

You may have a ding in your prop causing a bit of vibration at that rpm.
Kind of like a mildly unbalanced tire on your car... you can feel it 45 but it stops at 65 .

No pin points... but maybe some ideas to follow up on.


Good luck.