Two Cycle Mix Question

[Hahn007]

Hi, I just bought a 1985 Evinrude 15 HP outboard and the attached tag specifies 100:1 fuel oil mix ratio. A couple of outboard repair shops have told me to run it at 50:1 however. Will this cause fouling of spark plugs, excess carbon build up etc? Any thoughts? Thanks in advance.

 

[Will Bark]

Re: Two Cycle Mix Question

50:1 is the mixture to use OMC messed that one up and had a lot of warranty claims I read about.

 

[Hahn007]

Re: Two Cycle Mix Question

I think the guy I bought it from has been running at 100:1. Any easy way to evaluate potential damage?

 

[emckelvy]

Re: Two Cycle Mix Question

If it's still running ok, doesn't make any nasty noises, and has good compression, I wouldn't worry about it. Just run it at a 50:1 mix from now on. If you're concerned about smoking, etc, use a premium synthetic TCW-3 mfr's oil, it should keep smoke to a minimum.

HTH..........ed

 

[Hahn007]

Re: Two Cycle Mix Question

Sounds logical to me. Any idea what the average compression should be on it?

 

[JB]

Re: Two Cycle Mix Question

The two cylinders should compress within 10% of each other.

PSI is not very important as long as it is above about 70 (rope) or 80(elec). Gauges, conditions and technique vary too much to set a psi criterion.