Correct Oil Ratio for Yamaha 5HP 2stroke

Chris · 27 April 2007, 15:18

I am bidding on a 10 year old Yamaha 5HP on ebay. The guy says it runs on 100:1 oil

etrol mix. Is this correct, it sounds like too little to me?

Chris

nyx2k · 27 April 2007, 15:21

my 9.9 runs at 1-100 but it doesnt rev high for long periods. if im going to use it at wot i use 70-1

Jizm · 27 April 2007, 15:48

The handbook says 100:1 but I usually run premix of 50:1/70:1

Chris · 27 April 2007, 16:49

Apparently the older blue coloured engines should run at 50.1 wheras the later grey coloured ones are 100.1

I got this from a Yamaha dealer.

Chris

codprawn · 27 April 2007, 18:51

The reason they say 100:1 is for the sake of environmental laws - for the sake of the engine 50:1 is much better!!!

Nos4r2 · 27 April 2007, 19:09

Apparently it does no harm running at 50:1.Apparently when running at 100:1 they run a bit hotter.

Searider · 30 April 2007, 15:19

Had a 4hp BLUE Yamaha in the late 80s / early 1990s.
And a 20hp BLUE Yamaha 20 in about 1990.

Both had 100:1 marked on them. Used to put a bit extra in for luck though - most other outboards of that time were on 50:1.

The 20 used to oil up a bit on 50:1 at river speeds.

Chris · 30 April 2007, 18:30

Guys,

It seems that the best bet would be to run it a 75:1 then ;-)

Jizm · 30 April 2007, 23:23

Quote:

Originally Posted by Chris1573

Guys,

It seems that the best bet would be to run it a 75:1 then ;-)

safe bet