Concerns about motor modifications to make SLEEPERS

[cajuncook1]

I'm only going to mention Johnson and Evinrude motors, because those are the brands I am most familiar with.

There are models such as the one list below that have the same blocks size and pistons, but have other modifications created by the engineers at the product houses during development that change the horse power rating for a motor.

1974 to 2000's 9.9hp and 15hp

1960's late to early 1970's 18hp, 20, 25hp motors

1980's 25 to 35hp motors

Late 1970's and 1980's 48, 50, 55hp and 60hp motors

These are just a few examples of motors that share a lot common lower units, power heads, exhaust housing, starter and cowls. This list is not exact and is not expected to be an exact list just an fyi for the bone picker crowd.

There are differences in reeds, exhaust tubes/tuners, carburetor venturi sizes. Some have the same power heads but different crankshafts and piston weighting to help handle the extra horse power. Some have the same power heads, but different carburetors, reeds, maybe the same exhaust tube, but a reinforced or sturdier lower unit to help with the extra horse power.

A lot of these motors were tuned down so the same power head and exhaust housings and lower unit could be used for multiple HP motors to save money in regards to reproduction.


The problem is there are several non-experienced or very little experienced do it your selfer's that in encourage people to make these alteration on motors they know little about.

"Hey just put a bigger carburetor on it or drill a larger opening to make it run better."

" I know this guy, who knows this guy, that knows this feller that made this change and the motor ran about 5hp better."

" Hey there is a guy that posted a You Tube video of increasing the HP on this brand of motor and he did this" and you see a guy flying across the lake at Warp 2 with a 6hp motor. (Hey it is probably going Warp 2, but that motor will not last very long....it was meant for attention and posting a video not as a solid, dependable good old fishing boat motor buddy!)



Please, I did not post this to insult anyone or demean anyone what so ever!! My reason for posting these comments is because unless you are a certified mechanic that knows those motors very well and can seriously walk someone through the change over process and help diagnosis, then you should not be advising someone.

If a person makes improper changes or incomplete changes to an outboard (to make it a sleeper) and it cause a lean running conditions and damages the motor due lack of oil or the motor over revs and throws a rod and severely damages the power head or lower unit. ***Then that person will suffer a significant financial loss***

Please be careful when offering advice on altering a motor.




Again, I am sincere, when I stated that I am not pointing any fingers or demeaning anyone. Just wanted people to please stop and think.

I know I am going to get stoned for making my comments, so the Kevlar helmet goes on!!!

 

[Aaron Lariscy]

I agree wholeheartedly with what you say, the same thing happens on several car forums I am a member of a guy posts wanting more horsepower outta his ride and people start recommending he put a different camshaft or bigger carb on his motor not paying any attention to the fact that if you change one thing you start a chain reaction and end up with a crappy running engine or having do dig deep into your pockets to support your modification.

 

[Lil' Blue Rude]

I try to make it a point to tell people about simple mods that won't (shouldn't) cause problems. If someone doesn't have the understanding of a motor before they start modding it they've kinda brought whatever happens to the motor on them selves. Motors can be modded beyond stock and still be reliable. Maintaning the motor is the key. A built motor needs a little more attention then a stock motor. Everyone says a built motor won't idle or they just aren't reliable. I own a hot little 40hp rude I built myself and it starts and idles better then a stock and hasn't left me stranded (knock on wood) for the past 3 years. Stock motor will last longer but not every built motor is junk. Strong motors can be built but people should do there own research and understand what every mod does and what that mod will effect. Not just your motor but others too. Just because it worked on this motor doesn't mean it will help yours.
Modding a motor isn't for everyone but it doesn't have to be a certified mechanic to mod them.
Not tryin to bash you guys either.

 

[cajuncook1]

Modding a motor isn't for everyone but it doesn't have to be a certified mechanic to mod them.
Not tryin to bash you guys either.

True, you don't have to be certified mechanic to modify a motor and the motor run great. People do that stuff all the time with racing motors and what ever float their boat.

My concern, is people who are not certified mechanics or at least very very knowledgeable and experienced with the motor they recommending modification being done. I have seen guys on others forums and yes this forum too recommend changes (modification) and when the person they are encouraging or "assisting" starts to run into problems and they don't know what to do, then you see no more assistance or comments from "Modification expert!" Then that person is stuck, because they though they would have adequate support.

Again, just giving a point of view and not bashing!!