Mercury KG4-H

[Boatboy88]

Hey everyone,
I am in the midst of purchasing a Mercury KG4-H and I am wondering are there any things that I should be worried about if I buy this motor?
I am aware of the cost of parts for these motors and I am capable of doing the work myself.
What kind of speed can I expect from this motor on an 8 ft three point hydro?
Thanks in advance,
Dan Scheda

[mike ross]

This motor was run in the A hydro class and ran speeds in the high 50's when it was retired for the newer Evinrude. It will depend on the baot prop and set up. Post a pic of your boat and set up and we will help guide you along.

[Boatboy88]

Hydro pics

http://www.glen-l.com/phpBB2/downloa...0414&mode=view
http://www.glen-l.com/phpBB2/downloa...0413&mode=view
http://www.glen-l.com/phpBB2/downloa...0411&mode=view

Sorry for the links but if you have any trouble I can post the files later but I don't have the drive that they are on.
Thanks again,
Dan Scheda

[3autility]

Kg4h

My guess is that with that boat you will see mid 40s, maybe a little higher.

[ZUL8TR]

kg4h

Hey everyone,
I am in the midst of purchasing a Mercury KG4-H and I am wondering are there any things that I should be worried about if I buy this motor?
I am aware of the cost of parts for these motors and I am capable of doing the work myself.
What kind of speed can I expect from this motor on an 8 ft three point hydro?
Thanks in advance,
Dan Scheda

What is the weight of the boat and you?

What is the vertical height of the transom motor board from the bottom rear to the rear top edge? Needs to be in the 16" range then add shims and kick out or in to get to best set up for your use.

Set up, engine revs and prop mean alot. I assume the quicki gear foot has 1:1gears?

[Boatboy88]

The boat and myself weigh a total of 240 pounds and the transom is in the 16" range.

[ZUL8TR]

gh4H

240 + engine at about 70 + gas, helmet jacket at 15 = 325. Tad less than the 330 lbs ASH min weight in the 1970's. So I suppose speeds should be about mid to high 40's with correct set up. If you could get that hydro to float the sponsons clear of the water that could put you faster. That hydro does not have a cowl to hide behind and deflect the wind that also provides some aero lift so there is a disadvantage there. Also are there air traps? If yes flip the boat so we can see the bottom. If not you may need to add them. Where do you have a turn fin, bottom (offsrt?) or rear of left sponson?

KG4H engines are small displacement and low hp and benefit from all internal and external tweeks and there are alot of them. They need really good sealing pistons and rings and straight bores and a well tuned ignition and timing set up.

[Boatboy88]

The turn fin is on the left sponson. What are the air traps? I am sure that the boat doesn't have them.

[T Chance]

The turn fin is on the left sponson. What are the air traps? I am sure that the boat doesn't have them.

Air traps keep the air under the boat and they don't let that air spill out behind the sponsons. I modified your photo to try and show what they would be like. You could consider them an extension of the vertical part of the sponson.

[KG4]

I had my KG4 on a 2005 K craft hydro and it ran 52 on gps but i weigh 198 at the time.A skinny guy in it would have ran very good.

[ZUL8TR]

air traps

T Chance Perfectly clear. Determining to terminate them to zero or 1/2" depth or so at the rear is a matter of testing. Wood easier to fabricate and attach, start with 1/2 depth at rear then can always trim down if needed. Depth above bottom (boat up side down) at rear lifts the rear and pushes down the bow. Your boat appears to not have that much lift to get the bow up. Try the boat with no traps and go from there.

[Affholter66]

Looks like a Clark Craft kit? I had one when I was a kid...we ran a KG4 on it as a Lake Racer and saw upper 40's...No Chines/Airtraps..Cool little Boat..."Floated"" through turns!!

[dndsam]

Dan,

You may want to set your steering up so you can tie it down off the side of the boat near the rear of the transom as depicted in the picture of my B hydro, highlighted in yellow. It will create a more secure steering feel and will help keep your boat steering straight easier will less feedback from the motor.

Air traps run from the end of the sponson tapered towards the back of the boat. Some boats have full traps that run all the way to the transom of the boat like depicted on my boat. Some boats have partial air traps that run part of the way. These air traps help create lift of boat to decrease resistance and increase speed. I hope this helps.

[Boatboy88]

The boat I believe is a Glen-L Tiny Titan. I will test out the motor on the boat before I try and fabricate air traps. Also I knew that I would have to reroute my steering if I upgraded the motor because the steering as of right now is very touchy. Thanks all for the help I'm sure I will need more of it in the future.
Dan Scheda

[jackbquick]

KG4H Hydro Rig

Dan, some other points about the KG4. The Phelon magneto will give you about 200 more RPM than the Scintilla. The Phelon from a KE7 will work. The KG4 came with either an AJ29 or an AJ36 carburetor. Later, an AJ32 which was on the KG7 was allowed wich gave you more air. You will have be careful with the air traps. The sponsons on the older hydros were deeper than the more modern ones. Under the wrong circumstances, you can get a suction and stuff. I know, I did it years ago when I was designing 4 point hydros. Good Luck Jack Deck