Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

[v12mac]

Yamaha pre-mix confusion

What is the correct ratio for a C 55 hp 2stroke 2 cylinder? (This motor did not come with oil injection) I have been running 50-1 with no problems, but some folks are telling me that the 2 cyl motors are set up to be pre-mixed at 100-1
Can any one shine some light on this? Are there 100-1 pre-mix motors out there?

Mac

 

[SCO]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

[
Hello Mac,

I'm going to add to the confusion. I have a 2005 50hp 3 cyl 2 stroke w oil injection. It doesnt use much oil. I am trying to calibrate it as we type. I marked the sight tube on the oil resevoir at full gas tank. It will take a while to run the gas through it but Ill measure the amount of oil to refil to my mark and the amount of gasoline to refill the tank. I have heard 100:1 for this engine but dont trust the oiler till I can see what it puts out. The manual does say that if the engine hasn't been run in a year, that you should start it with 50:1 mix. Their current models greater than 50 hp all have oilers. It doesnt specify an oil ratio for these on the yamaha website or in my manual. For the new current tiller models through 25hp, the website specifiys 100:1. This url should take you to the yamaha owners manual location.
http://www.yamaha-motor.com/outboard/service/viewmanuals/outboard_manuals.aspx

I looked up a 2000 c50 and it takes 50:1. Let us know what you find

 

[deejaycee_2000]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

50:1 ... 50:1 .... 50:1 ...... an engine with oil injection will mix the oil according to the rpm, at idle it would be about 100:1 or about 125:1 and at pullaway maybe 30:1 or 50:1 depending on the work load ..... if you stop and pullaway and stop and pullaway it will use much more oil than just cruising without stopping, check your oil level after skiing for the day, you will see the difference ....... it is better to just run your 2-stroke on 50:1 even if the manual says 100:1 it won't hurt the motor ....... I have a 15hp yamaha that is supposedly 100:1, but I run it on 50:1 to be safe, never had a problem ......

 

[v12mac]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

I'll stick with 50-1 on this motor.

Deejaycee, in keeping with your motto "The maximum hp is never enugh" We set up this 13' whaler with a C55hp Yammie.
I wonder if it will float a 90hp??.....

Mac

P.S. I don't want to start a whole Hp thing, this boat is never used and nobody will ever ride in it.

 

[deejaycee_2000]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

hehehehehe ..... yeah that can be dangerous, some people on this forum get worked up very quick when it comes to going over the max hp, but everyone is entitled to their own opinion, here in SA we just do whatever we want so it doesn't matter to me ...... I am sure that whaler would fly with that 55 yummy, although that is a 2-cyl right? it is pretty light compared to a 90hp so the whaler woul be cool with the 55, with the 90hp, I would not attempt that myself hahaha, the 90hp is very heavy so I would say no it probably would not float, but you would never know unless you try it , try everything at least once I always say hehehe

 

[rodbolt]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

actually the 13 whaler is scary with a 90 yamaha.
the 70 is all I wish.
we do have nuts here as well .
on the fuel mix, most smaller yamahas were technically desined to run at 100 to 1 but in practicile experience 50/1 works better in real life.
the precision blend oil injected yamahas will vary the amount of oil injected depending on throttle angle and engine RPM. the actual ratio is determined by the throttle angle and the speed of the pump(RPM)

 

[v12mac]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

Deejaycee, yep it is the 2cyl. We got lucky and found it here locally in great shape, may have been a freshwater only motor. It runs great and is the fastest 13 I've ever run. I had a 7 1/2 hp on a 13 when I was a kid and I thought that was fast!

Wow, Rodbolt I was just dreaming but it seems like you have seen one with a 90hp!

Mac

 

[rodbolt]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

not that I reccomend it, but yes. I have an idiot friend that did it.
dunno who was the biggest idiot.
him for doing it or me for actually riding in it, once.
however your also chatting with an idiot that put a 150 yamaha on a 15' monark mcfast. .
above 60 the steeering locks .
dont ask dont tell.
one day I looked up, had a motor, had a hull, had a few beers and the rest was history.

 

[deejaycee_2000]

Re: Yamaha pre-mix confusion 2 cylinder engines 50-1 or 100-1

too be honest .... not even me will attempt that with a 90hp standard engine .... if it is a light motor like my 50hp engines that is boosted to 90hp (yet to be proven by me soon) maybe then .... hey rodbolt you should have a ride with me on my racing inflatable ... afterwards we drink ... hahaha .... also testing my 16.5 foot raven with a 200hp yummie soon .... should be fun .... I am crazy, maybe, but not an idiot ... safety first (not) ..... anyway, those 2 cyl 55hp yummies are "never say die" motors, as a kid I drove the hell out of one I have, still runs perfect today with no problems .....