newbie needs help, boat scared of water!

[centexhomeboy]

I am very new to rc boating but not most other rc and I recently bought a .21 hydro setup with a k&b 3.5 inboard mounted in it. I cleaned the motor and fuel tank up throughly. The problem I'm having is once i get the thing started and leaned out, I have very little throttle response and once i lay it in the water it always stalls out immed, like the water loading on the prop kills it?
I've installed a filter on the fuel supply to the eng in case any trash remained in the tank but it's never dirty. One thing I have no clue on is the butterfly throttle being located at the exhaust port and used to control throttle. I suppose the seal at the exaust might be part of my prob as sometimes the bolts that hold on the exaust manifld loosen and i see fuel/oil bubbles at the joint. but theyre after the butfly valve so maybe not so much? I've installed new pressure line and fuel supply line so no cracks or leaks there.the engine has good compression and runs great seems like but only with the prop in the air. Could i be using a wrong glow plug or something? i saw that k&b reccommends a long throw plug? I just installed a brand new standard plug don't know about it being long throw or anything. One other clue sometimes when it takes a long time to get started, it will lose pressure and fuel supply will back down the supply line and i'll have to pick the boat up and shake it while I'm starting it and the supply will return with pressure and sometimes will then start. could it be a bad fuel tank? I would have to tear the hull up to get to the tank itself and after i throughly cleaned it, it seems to function ok. I was also wondering if it may be the way I'm setting the boat in the water because sometimes It may go in nose first due to bank condtions and not a perfect launch although I dont know exactly what a perfect launch is. are you suppose to toss it in or set it in? or should it matter that much? Any help would be appreciated and probably keep my investment safe as well. thanks for reading my novel as well. :cool: :confused:

[DLM]

Vaccuum leaks are commonplace. I used to use very light oil where gaskets are and see if it changed rpm any. When you get done with that area, wipe off oil and go onto another area. Another area is warpage where too much torque has been applied and generally you have to replace that component. Another area is needle that has been seated to deep and a groove or nitch has made an impreesion on needle, so adjustment is will make you talk FRENCH under your breath. MAKE sure you wear ear plugs and i believe a handheld tach can be used to detech rpm change!

[BoatDoc]

what you want to do is richen it up! exhaust throttle engines are gas hogs and your needle should be set rich. at low rpm's they can be hard to keep running, you need to stay on the gas. the problem is this, you need a nice level flat launch...while holding down the throttle. the exhaust throttle motors are super touchy like that. they like to run one way and that's wide open. due to the way an exhaust throttle works, they are easy to kill at idle. it works basically by choking the engine when you are below WOT, thus no real power is made. however, at WOT they make gobs of power. it may be easier if you have a buddy to launch for you. if not, try to trim up the idle a bit so you can launch with enough power to keep the engine running. once you're on the water, try not to come off the gas too much or you will most likely kill the engine.

[centexhomeboy]

cool, thanks guys for the quick advice on a beautiful saturday morning here. I've got some good info to start with and a full day ahead to try it out. hopefully she'll be water logged by the time its over. One other thing I was curious about, Does anyone know if my engine should have a head gasket on it or an exhaust gasket on it because mine doesn't? If it is can I just make one from auto gasket mat'l cause you gotta know parts are scarce for these k&b oldies. thanks and I'll let you know my results in a little while

[BoatDoc]

these engines don't have head gaskets (so to say). they have head shims. the shims are used to set the head clearence. you can add/remove them depending on conditions and amount of nitro and other mods. there is not an exhaust gasket on the K&B outboards that i have, so i imagine there's not one on your inboard. a couple more things. K&B motors like nitro!!! i like to run 30-35% in mine. glow plugs can get costly once you go over that. MECOA now sells all the K&B stuff, so you can get your parts on their website. i think everthing for the 3.5's is back in production. good luck!

[Hydro Junkie]

I would start with looking for leaks. I have guys in the scale club I belong to that used exhaust throttled K&B .67s without any of the problems you are having. They would idle without stalling and always had plenty of power. To the other drivers, these boats were to be feared anytime they showed up. As for your question about "to throw or not to throw", definately throw it. Boat Doc is right(and I hate to admit this, he might get a swelled head :D ), a nice level toss is best. It is also better to have a second peson with you any time you are out running. They can launch your boat and look for debris in the water ahead of the boat. The big thing though, and most boaters don't like to talk about this, is in case you get injured at the lake. It's hard to get to a hospital while you are watching blood spirting out from were a finger used to be. Which brings me to my question for you. Does the stand you use provide protection from contacting the prop? If not, you need to get/build one that does, so the affore mentioned doesn't happen. It's easy to get comfortable around a spinning prop, but it's also dangerous. ANY BOAT STAND that doesn't protect the people in the pits from a spinning prop is a danger to everyone. I was hit by an airplane prop years ago and almost took off my finger. If it had been a metal boat prop instead of a nylon Master Airscrew, I would have. As I said, most boaters don't talk about this aspect of boating, as they are scared of chasing away potential people to run with and race against.

[DLM]

My left wrist inside got got in four places about a quarter inch apart and one inch in lenght from a spinning octura 642 prop and had to tie off wrist to slow down the red. It happens so fast too but was lucky. This sounds stupid but if a guy had a fishing pole and tied onto the bow and reeled in ( the other gUy ), it would sure lessen the injury part.

[DLM]

Storms coming thru ( bad )! Just put like a trimmer cutter on left side of bow tip and pull straight and when you feel full power or speed, turn right to cut fishing line, don't laugh it might work!

[BoatDoc]

i just thought of something, is your fuel pressure coming from your exhaust or the crankcase??? you need the extra pressure provided by the crankcase to get enough fuel into the motor. if you're just taking pressure from the exhaust, it may be part of the problem. like i said before, exhaust throttle engines are gas hogs.

[DLM]

I firmly believe and i endorse it, RUBBER Bands would be cheaper!!