evinrude 5hp

[Lubosleftboot]

I have tried to search but I keep getting messages about not enough letters in my search criteria... so I am starting this thread...

I have a 1987 5 hp evinrude 164cc twin cylinder motor and I have since found out that the 8 hp engine is the same cc so I got to wondering how I could get those 3 extra horses...

How is my motor restricted?Is it the carburator?The inlet manifold?the exhaust port size?

Do any of you fellas know?Any advice or pointing in the right direction would be appreciated...


Regards LLB

 

[R.Johnson]

Re: evinrude 5hp

This question has come up before, generally changing a 9.9 to 15. Most time's it's cheaper, and easier to just buy the engine your after. Also, you probably won't notice the difference either way.

 

[Lubosleftboot]

Re: evinrude 5hp

This question has come up before, generally changing a 9.9 to 15. Most time's it's cheaper, and easier to just buy the engine your after. Also, you probably won't notice the difference either way.

Why is that RJ? If the cubic capacity is the same yet there are different power outputs then the motors must be restricted....This can be done by any of the methods I have already posted and if possible I would like to find out what the difference is as I have been offered a dead 8 hp for spares and it looks exactly the same as my motor.


Thanks for the reply though....

LLB

 

[wbeaton]

Re: evinrude 5hp

Everything you need to know is in this link...

http://epc.brp.com/default.aspx?brands=ej&lang=E

Check out the parts diagrams for both motors and see which parts are different/compatible. Maybe you could get the 8 hp going from parts off of your 5 hp. That's as much help as I can be. I don't know anything about those particular motors.

 

[Lubosleftboot]

Re: evinrude 5hp

Everything you need to know is in this link...

http://epc.brp.com/default.aspx?brands=ej&lang=E

Check out the parts diagrams for both motors and see which parts are different/compatible. Maybe you could get the 8 hp going from parts off of your 5 hp. That's as much help as I can be. I don't know anything about those particular motors.

Thanks for the reply from what I can see this motor appears to be restricted via a smaller main jet as this is a relativly simple job to do I will change the main jets over and see if their is any difference....thanks for the input

LLB

 

[JB]

Re: evinrude 5hp

No, Lubo.

Changing the jet will only get you a lousy running 5HP.

No simple modification is going to increase HP by 60%.

 

[CATransplant]

Re: evinrude 5hp

Here's the deal: Change the jet to a larger size, and all you do is richen the fuel/air mixture. That won't give you more power, it will give you less.

If the two engines differ in a single thing, it would be the throat size of the carburetor. Larger carburetor means more fuel and air at the right mixture. The actual ratio of fuel to air doesn't change, and that's the function of the main jet.

Now, I haven't looked at the 5 hp versus the 8 hp. You'd have to compare part numbers for carburetor, heads, exhaust parts, center leg section, etc. Where they're the same, they don't matter.

I'm betting that there is more than one area where they're different. Go search in the diagrams on the Bombardier site and see if you can find where the two engines are different. But you have to check part numbers of things against each other.

Changing the jet will do nothing except foul spark plugs and slow your engine down.

 

[F_R]

Re: evinrude 5hp

CATransplant is right. Listen to his sound words of wisdom.

 

[jauguston]

Re: evinrude 5hp

I am fairly new here but I do know a little bit about the 8hp, I have one. As Steelspike said it is rated 500 rpm higher than the lower powered engines of the same family. Mine will turn 5700 on a 12' Crestliner Jon boat with the stock 8 1/2" X 9' prop with just me in it and it goes 18 mph on my GPS. I just got it recently and it had a few problems I dealt with and now it runs sweet.

Pretty darn good performance for a engine that only weights 56#!

Jim

 

[Lubosleftboot]

Re: evinrude 5hp(advice)

Re: evinrude 5hp(advice)

CATransplant is right. Listen to his sound words of wisdom.

Ok guys I will listen to you fellas as you are obviously more clued up than I am on this subject..Thanks for the replies I will just buy a bigger motor...


LLB