Carb sizes

[weezerr2183]

I have a 1981 35hp Evinrude. I believe it may have a 50hp carb on it. Is there some way to determine if this is true? Like checking jet size or something similar? I pulled the bowl and the jet set is just a small brass tube inside a larger brass tube with four holes, two on each side. There are no markings on them, numbers etc. The carbs I'm used to working with have markings on the jets. How do I determine what jet size that I have? What are the stock sizes of the 35hp? 50hp? Would a change to larger jets be the only difference between a 50hp and a 35hp? Or would the reeds have to be changed also?
Any information would be appreciated and thank you in advance.

 

[racerone]

Those brass tubes are not jets !------Small brass tube is the idle feed.------Large brass tube is the nozzle.-----------The high speed jet you are looking for is screwed horizontally into the bottom of the float bowl !!!

 

[weezerr2183]

I figured that the small tube was the idle. And the large tube was the main feed. Do you have a picture or a parts breakdown pic showing where exactly the high speed jet is located? Also do you know how I may determine what size I currently have installed?

 

[racerone]

???---The high speed jet is screwed horizontally into the bottom of the carburetor bowl as clearly stated.----Remove it and read the number on it !!

 

[weezerr2183]

OK, thank you!! I don't remember anything besides the plug being screwed into the bowl itself.

 

[racerone]

Follow good advice and you will learn all about this.

 

[weezerr2183]

Two stroke fuel metering is a new system to me although I'm sure there are many similarities to four stroke. I will take a close look at the carb over the weekend.

 

[weezerr2183]

OK, where is it?

 

[racerone]

The last picture is the carburetor bowl.-----It is screwed in horizontally.---Remove the hexhead drain plug to see those threads ---1/4-NC threads are on the jet.

 

[weezerr2183]

it says 59D

 

[racerone]

That is what the parts list says for an 81 model 35 hp.

 

[weezerr2183]

True, according to the parts list its also the same number for the hi speed jet on the 50hp carb. The part numbers for the pistons between the two engines is different leading me to believe that the displacement is the main difference between the two among other things I'm sure. The info I was hearing, something I call "bro science", was that the carb jets and reeds if these engines have them was the only difference.

 

[racerone]

???----How many carburetors on the 50 Hp model.--Have you checked cubic inch displacement between the 2 motors.----Total amount of air moved at rated RPM ??

 

[weezerr2183]

Just one carb on the fifty. And I stopped looking into it when I saw that there were different part numbers for the pistons relative to each engine. Assuming on that information that the displacement must be different. I don't have manuals for either engine so I'll search around online to find the cc's of each.

 

[racerone]

What model 50 only has one carburetor !!!!!!!!!!!

 

[ondarvr]

The jet size is NEVER the only difference between different HP motors, the jets are different because other components in the motor are different which require the different jetting.

 

[weezerr2183]

I looked at the IPB for the intake on the fifty and it does have two carbs, you're right. And yes there are quite a few difference between the two hp engines. I hear people talk about small differences between the engines that require "just a change of the jets and/or the reeds". So, instead of staying ignorant I sought out information on here, the best boat forum. Thank you for your input, and help I've learned more about these motors with your advice.

 

[ondarvr]

Anytime someone says its just the jets they have no clue as to what they are talking about.

There are a few motors that can have the HP increased without a great deal hassle and fiddling, but they aren't as common as most people think.

Most of the time it's costly, time consuming, and frequently disappointing when all is said and done.