boat racing

[kibol720]

can u help me about my engine i have gx390 and i want to mod this engine for boat racing and i need speed..what should i do first..Is it ok if i go to larger valves and 34mm carb?thanks

 

[mckutzy]

Hello and welcome.
How is the engine mounted, inboard or outboard?
Long tail or surface drive?

These help out in determining if you can use some gearing or if its direct drive.

 

[kibol720]

long tail it is direct drive....

 

[kibol720]

and also mounted inside and direct drive...

 

[OzFab]

I'm thinking a 4 stroke engine may not be your best option as your speed will be limited by the max RPM of the engine which is 3600rpm stock; to get it to 6000rpm will likely cost a few hundred dollars &, maybe, a comperable 2 stroke would be more suitable, like a jet-ski or snowmobile engine, those things do 7500+rpm stock... unless, of course, your racing class calls for a 4 stroke engine...

 

[firemanjim]

Uhhh.... That is awesome! Can you post more pics please!?! I keep seeing you guys making boats.... I'm still trying to finish my go kart, and im getting boat fever.... Plenty of water around here to play in....
Oh yeah, !
For more speed, you need more power. More power will let you use a more aggressive prop. The easy, cheap mods would be free flow exhaust, free flow intake/air filter, and rejetting the stock carb for more fuel. The biggest increase in HP will be from removing (not disable ) the rpm governor, so you get 2x the USABLE rpm..... If you advance the timing a little, you gain a little more hp. There is a lot you can do, and most of it cheaply, diy style.... If you built that boat, you can do the mods.....

 

[kibol720]

Uhhh.... That is awesome! Can you post more pics please!?! I keep seeing you guys making boats.... I'm still trying to finish my go kart, and im getting boat fever.... Plenty of water around here to play in....
Oh yeah, !
For more speed, you need more power. More power will let you use a more aggressive prop. The easy, cheap mods would be free flow exhaust, free flow intake/air filter, and rejetting the stock carb for more fuel. The biggest increase in HP will be from removing (not disable ) the rpm governor, so you get 2x the USABLE rpm..... If you advance the timing a little, you gain a little more hp. There is a lot you can do, and most of it cheaply, diy style.... If you built that boat, you can do the mods.....

thanks mate..i'll post some picture later...how about the cam which is suitable for speed?high duration or something

 

[kibol720]

I'm thinking a 4 stroke engine may not be your best option as your speed will be limited by the max RPM of the engine which is 3600rpm stock; to get it to 6000rpm will likely cost a few hundred dollars &, maybe, a comperable 2 stroke would be more suitable, like a jet-ski or snowmobile engine, those things do 7500+rpm stock... unless, of course, your racing class calls for a 4 stroke engine...

but yes we are racing class here 4 stroke engine...and also very hard to find here jet-ski or snowmobile engine

 

[kibol720]

Hello and welcome.
How is the engine mounted, inboard or outboard?
Long tail or surface drive?

These help out in determining if you can use some gearing or if its direct drive.

engine mount inboard long tail and direct drive

 

[kibol720]

need help

Uhhh.... That is awesome! Can you post more pics please!?! I keep seeing you guys making boats.... I'm still trying to finish my go kart, and im getting boat fever.... Plenty of water around here to play in....
Oh yeah, !
For more speed, you need more power. More power will let you use a more aggressive prop. The easy, cheap mods would be free flow exhaust, free flow intake/air filter, and rejetting the stock carb for more fuel. The biggest increase in HP will be from removing (not disable ) the rpm governor, so you get 2x the USABLE rpm..... If you advance the timing a little, you gain a little more hp. There is a lot you can do, and most of it cheaply, diy style.... If you built that boat, you can do the mods.....

here's the pic..

 

[kibol720]

here are some of our racing boat picture...we only lack of speed..hope u can help me

 

[firemanjim]

What's with all the tubing coming out of the engine? Especially on the side, where 2 come out of the engine block? I hope that isn't intended to run a pulse fuel pump.....

 

[kibol720]

What's with all the tubing coming out of the engine? Especially on the side, where 2 come out of the engine block? I hope that isn't intended to run a pulse fuel pump.....

ohh its a water cooling system..there's a pipe inside..bcoz when our engine is hot our boat run slow...so we put a copper tube inside to cool the engine..we ran 95 octane gas fuel

 

[firemanjim]

ohh its a water cooling system..there's a pipe inside..bcoz when our engine is hot our boat run slow...so we put a copper tube inside to cool the engine..we ran 95 octane gas fuel

Ahhh, how interesting! How well does it work? What are you pumping the water with?
If your engine is getting hot, it may be that it's being over worked/stressed. Doing some cheap mods to free up some hp might just help out all the way around....
I would do the typical mods. See if the engine is running cooler, without the coolant lines.
If you want more speed on the water, you need a more aggressive prop. In order to efficiently run that prop, you need a certain amount of horse power. Being that your running hot, you might have the prop, but not the hp to push it right. Everything has to work hand in hand, to be efficient.
Since you put in a cooling system, which is pretty dang cool if you ask me, what else have you done to the engine to make it run better?
EDIT
Please fill in your location, so we know where you're from....

 

[Poboy kartman]

OK!!!! Enough of this crap.....where are you from???

Cooling system is a "cool" idea....

 

[kibol720]

Ahhh, how interesting! How well does it work? What are you pumping the water with?
If your engine is getting hot, it may be that it's being over worked/stressed. Doing some cheap mods to free up some hp might just help out all the way around....
I would do the typical mods. See if the engine is running cooler, without the coolant lines.
If you want more speed on the water, you need a more aggressive prop. In order to efficiently run that prop, you need a certain amount of horse power. Being that your running hot, you might have the prop, but not the hp to push it right. Everything has to work hand in hand, to be efficient.
Since you put in a cooling system, which is pretty dang cool if you ask me, what else have you done to the engine to make it run better?
EDIT
Please fill in your location, so we know where you're from....[/QU


there's a hole at the bottom of the boat that connect to the hose from the engine so when the boat run the seawater will pass through the hose...
other mods :
carbs 34mm
large valve 40 and 35mm intake,exh
cam that we dont know what size,duration or lift we just weld it the lobe
94mm piston with stock rod
roller from mitsubishi gm40
advance 4 degrees
stock flywheel
stock crank..i know this types of mods is crazy thats why im asking for a help..can u give me the exact mods for true speed..i'll appreciate any help...thanks

our max boat speed 59 mph...

 

[vpd66]

Did you build the boat?? I've never seen one like that. Any more info on the boat???

 

[kibol720]

Did you build the boat?? I've never seen one like that. Any more info on the boat???

no my friend build it...where u from?

 

[kibol720]

OK!!!! Enough of this crap.....where are you from???

Cooling system is a "cool" idea....

is it ok to remove the balancer?

 

[Poboy kartman]

is it ok to remove the balancer?

I doubt it....but post up a pic of what you are calling a "balancer" .....

And thanks for filling out your profile......