Get more out of 86 Johnson gt200

[Mike2552]

Can anyone tell me what I can do to get more out of my motor seems to have the same block *** 225 but I think Jets or something let me know if anyone has some cheap home ideas thanks

 

[Bob_VT]

Re: Get more out of 86 Johnson gt200

When was the last tune up? Last Carb rebuild? Last de-carb? If you do not know that history then your motor needs work. What is your current wide open throttle?

 

[Mike2552]

Re: Get more out of 86 Johnson gt200

I got it from a guy who had it In a shed so yes I know nothing but I do know it has 120 psi or so all 6 cyl wide open is at 5900 at 57mph GPS and how affective is a decarb and how do I do it

 

[Mike2552]

Re: Get more out of 86 Johnson gt200

Also what could be wrong in the carbs to cause a problem it runs great except not giving up expectation , I had suspected possibly not given enough fuel mayb

 

[Bob_VT]

Re: Get more out of 86 Johnson gt200

Well you are running at WOT (actually kind of high since I believe 5500 is where you want to be)........ sounds okay...... maybe the boat is overweight too.

Are you trying to turn this into a race motor or keep it as a fishing motor? You could be on the edge of having huge expenses........ racing the motor is not cheap.

 

[Mike2552]

Re: Get more out of 86 Johnson gt200

Well you are running at WOT (actually kind of high since I believe 5500 is where you want to be)........ sounds okay...... maybe the boat is overweight too.

Are you trying to turn this into a race motor or keep it as a fishing motor? You could be on the edge of having huge expenses........ racing the motor is not cheap.

No not Gona race just want the best performance and reliability for fishing but maybe the hull is heavy do you know anything about how to position a jack plate like how high should I go? Should I go as high as I can before losing water pressure

 

[Bob_VT]

Re: Get more out of 86 Johnson gt200

I would get the boat weighed....... it is not uncommon to see waterlogged flotation in a 1990 boat. Your dry hull weight should be between 1300-1450 lbs depending on the model. If you are concerned about water pressure then get a gauge installed. About 1 minute of WOT with low water pressure will trash that motor and turn it into scrap. My previous bass boats were equipped with water pressure gauges/temp/tach. The jack plate has no rules and every boat has a sweet spot.

 

[Mike2552]

Re: Get more out of 86 Johnson gt200

So say the boat is water logged would I rip it out and say screw it or replace it ,the hull is one of the detest when it's in the water doesn't take on any water . I kinda pieced this boat together I'm here in Michigan and won't be using the boat until march when walleye run so I got time want to get it right Detroit river is tretcherous

 

[Bob_VT]

Re: Get more out of 86 Johnson gt200

Do a SEARCH for "waterlogged" and read the restoration section of the forum.

 

[JB]

Re: Get more out of 86 Johnson gt200

In most rigs extra performance is available by fine tuning the prop and rigging. You could go up an inch in the prop pitch and use a SS prop.

Do you have PT&T? How do you use it? At WOT, is she trimmed out just short of ventilating or porpoising?

How high is the AV plate relative to the bottom of the hull? Do you have the engine set back from the transom? At the transom most outboards can handle an inch or so above the bottom. Add an inch for each inch of setback, if any.

Along with a good Link 'n' Synch those things should get the best performance without modifications that might risk reliability and longevity. I doubt that a decarb would be of benefit to an engine that compresses 120psi on all 6 and turns 5900rpm at WOT..

 

[Mike2552]

Re: Get more out of 86 Johnson gt200

In most rigs extra performance is available by fine tuning the prop and rigging. You could go up an inch in the prop pitch and use a SS prop.

Do you have PT&T? How do you use it? At WOT, is she trimmed out just short of ventilating or porpoising?

How high is the AV plate relative to the bottom of the hull? Do you have the engine set back from the transom? At the transom most outboards can handle an inch or so above the bottom. Add an inch for each inch of setback, if any.

Along with a good Link 'n' Synch those thing should get the best performance without modifications that might risk reliability and longevity. I doubt that a decarb would be of benefit to an engine that compresses 120psi on all 6 and turns 5900rpm at WOT..

Thanks the boat has 6" jack plat right now cavatation plate is 1" above the pad I get no rooster tail just a little bubble 2' high and 3' long trimmed all out at 57mph I think I need to come up

 

[metriccrescentwrench]

Re: Get more out of 86 Johnson gt200

Thanks the boat has 6" jack plat right now cavatation plate is 1" above the pad ...

I looked around to see if I could find any photos to give you an idea of how high an engine sits on a jackplate when the prop centerline is about 3 inches below the pad. Here's what I could find. Yes, you might benefit some by going higher, but as I said in your other thread don't even think about going this high without at least a water pressure gauge (and if you so much as see the pressure drop for an instant when you're experimenting with engine height shut down immediately).

As far as a rooster tail, a lot of that has to do with prop design. I run an OMC Renegade-Bass 4-blade prop (that's not the Renegade in the photo), not because it was the absolute fastest prop I could find but because it had very nice all-around handling characteristics as recommended to me by others with the same hull.