I've been looking over some standard go kart racing modifications for the 13 hp Honda. One is to remove the internal governor. Has anyone done this? AGK says it boosts rpm dramatically and performance. Anyone done this?

Second question that I can't seem to figure.. The throttle has a limiting screw that's adjustable.. anyone ever play with it? If you open up the throttle more are you tempting fate on blowing the engine? just some Q's for anyone that tinkers with the stock engines. This is on a beavertail.

SJ, there's three ways to go here. (1) Start modifying it (2) then modify it some more or (3) get a bigger motor that'll do whatcha need. Mark the screw and adjust it then see what happens it prolly ain't gonna pop from adjusting any stock controls. Removing the gov assy is another story though. See 1 & 2 Good luck, may the duck boat motor gods have mercy on ya.

thanks bug..
not really what I was looking for...
anyone do mods?

Sj,

I have the same motor that I just bolted to a Backwater glider kit. When I got the motor, it revved to the stock 3600. I had the same questions as you and didn't really feel like taking apart the motor to remove the governor. In the go kart forums a guy suggested just removing the governor screw and that would increase rpm's and still be very reliable.

After reading that I pulled the screw and the motor gained another 700-800 rpms to 4300-4400

My next order or business is to get a Robertsons torque tube and pull the stock muffler and throw on a K&M air filter. The go kart guys say those two mods alone will give you an increase of 15-20% hp. We shall see.

Garza
you will have to let me know how that works out! I just ordered the Carb insulator replacement with a vacuum takeoff so I can add a fuel pump and get rid of the gravity tank which is way too small for cruz'n on the Mississippi. I should get that all done by next week I hope!

Did you remove the throttle limiter screw? I just adjusted mine which was way in and stopping the throttle at about 2/3's. I screwed it back and it really lifted the RPM's on that last 1/3rd. I think we might be talking about the same thing?

Is that the open air filter? I hear that lifts HP way up? You will really have to let me know how it all goes! I haven't played with small motors for quite a few years.. kinda fun reading up on this motor and how big it is in the kart racing.

go to nrracing.com and look at the hop up kits for your motor. also check out http://affordablegokarts.com/ and look at the right of the page there is a DIY section. all you need to know about that motor. as far as the governor goes it will increase rpms if you remove it but when the prop is in the water you wont notice much without other mods. what i have learned with these small motors on mud motor frames is that all the power is made in the head and cam. if you really want the thing to haul look at spending at least 400 bucks on parts and doing some port work yourself to save cash. there are plenty forums with the kart guys who have built tons of 390's. but most of them are building these motors to run high speeds and 8k rpms. some guys run oval tracks and the heavier guys like to get torquey motors. check out http://karting.4cycle.com/ for info on builds.

Sj,

Yeah that's the screw, I completely removed it.

I have been looking for threads on here with more info about this motor from other people that have modded it, maybe we can keep this thread alive with progress of our motors.

I'll keep you posted on any mods I do. Let me know what you do as well!!

Garza
Will do!

Heres a great service manual web page for the motor. All kinds of details. you'll want to bookmark it!

Also, I agree on the gas tank, I may end up going the route that you're taking.

I just completely modified mine by removing the governor, putting in a billet rod, head ported and milled, nrracing marine cam, removed balance shaft, and a mikuni 32mm carb. I went from 10mph to 18mph. It revs to 5000rpm at its top speed. Removing the governor is definitely a big performance gain but you may need to have some extra performance mods for your motor to have enough power to spin the prop faster. You definitely need heavier valve springs and an advanced timing key to start off. Its really not a hard job to remove the governor and it should only take about an hour. I used a brake lever from a ten speed for my throttle. Affordablegokarts.com has all of the tutorials. I would read all of them before you sttart modding.

I just completely modified mine by removing the governor, putting in a billet rod, head ported and milled, nrracing marine cam, removed balance shaft, and a mikuni 32mm carb. I went from 10mph to 18mph. It would not plane with 2 people before and now it planes easy It revs to 5000rpm at its top speed. Removing the governor is definitely a big performance gain but you may need to have some extra performance mods for your motor to have enough power to spin the prop faster. You definitely need heavier valve springs and an advanced timing key to start off. Its really not a hard job to remove the governor and it should only take about an hour. I used a brake lever from a ten speed for my throttle. Affordablegokarts.com has all of the tutorials. I would read all of them before you sttart modding. My boat is a riverhawk b-52 duck boat.

Just finished modify'n the gas system. Installed a pump to connect to the standard boat fuel tank. Of course every connection point on the fuel pump is 1/4 hose and every other connection is something different.
The boat line is 5/16 so I needed to put together a brass fitting going from 1/4 to 5/16. One threaded 1/4 (1/8 thread) male to a 5/16 (1/8 thread) female.

The carburetor insulator that I purchased with the vacuum line seemed to be about 5/32 hose. I ran that with a plastic 5/32 > 1/4 hose connector.

The Fuel line going out from the pump to the carb is another size. I used a 7/32 hose with another plastic 1/4 connector. I'm waiting to see if the plastic holds up to the gas. I got if from an auto store so lets hope. If not than I need to make one like the boat line.

I used a couple of screw couplers to come off the carburetor rods to hold a simple sheet metal holder for the pump.

First time I turned it over.... wham .. working. Not too bad if you get the carb insulator with the vacuum, all the gaskets, especially the carb insulator to the head gasket. I had to make my own. Know you will be dealing with three sizes of hoses.

I kept the tank right where it is and everything else is a quick disconnect if, for whatever reason, I wanted to run the tank.

good luck!

Update
So the pump all works but.... after running full tilt and dropping the throttle to idle, I'm getting over flow gas coming out the carburetor insulator overflow hole... and plenty of it. I think I have to adjust the carb to compensate for the change from gravity feed to a pump that pumps continuously. I'm waiting to talk to a local Honda engine guy before I start adjusting the carb. Tank still works so I'm still hunting!

I tried to install a mikuni fuel pump on mine and I had the same problem. I just took it off and I run gravity with a shut off valve bolted to the flywheel cover.