Twin SGX

[XtremeRcBoats]

Tnx guys, I wet sanded them yesterday and will put the second layer on on Thursday. The MAC84's are brand new, what is the best way to run them in.? How manny tanks?

 

[charles siler]

Man you are going to have some fun . here ate some pics of my 90 that may help with 3rd needle s and if you can buy a pair of andy browns parabolic 84 pipes or AA 80 pipes they will realy wake up thoughs motors and if you dont have andy's 3rd needles

he maid me change mine to OS 9B they are better. Dude You are going to have some fun . Oh AA racing are going to have 84 parts next year

 

[gil sonsino]

Great boats with fast engines.My SGX's are still great contenders with silver head Mac's 84 using CMDI 3rd channel.The only thing I would suggest to change using these needles is the position of the fuel lines.......the botton lines should go to the carb and you won't have any feed problem.Gill

 

[Buckshot]

Glad to see your back on the twin build.

Here is the first set up I used. It worked okay but was a tubing nightmare!

This what I ended up with before the boat was sold. Worked good and was a little cleaner set up.

-Buck-

Looks good Paul.

It's gonna haul the mail for sure.

Some how the photos in my previous post got deleted, I have re-inserted them.

 

[XtremeRcBoats]

Thanks Charles, great pictures. I put the 3rd needles at the other side of the engine (forgot to take a picture of it). I think i have the same needles you have.

The pipes i'm using are AB parabolics but the are modified with an extra muffler section to keep the noise levels down. We can only run 80 dB overhere. See picture below.

 

[charles siler]

Glad to see your back on the twin build.

Here is the first set up I used. It worked okay but was a tubing nightmare!

This what I ended up with before the boat was sold. Worked good and was a little cleaner set up.

-Buck-

Are you still using the rabbit needles on your newer twins

 

[Buckshot]

Glad to see your back on the twin build.

Here is the first set up I used. It worked okay but was a tubing nightmare!

This what I ended up with before the boat was sold. Worked good and was a little cleaner set up.

-Buck-

Are you still using the rabbit needles on your newer twins

No.

 

[charles siler]

Thanks Charles, great pictures. I put the 3rd needles at the other side of the engine (forgot to take a picture of it). I think i have the same needles you have.

The pipes i'm using are AB parabolics but the are modified with an extra muffler section to keep the noise levels down. We can only run 80 dB overhere. See picture below.

there are two types of thoughs needles one has a 1/2" and the other is 3/4" taper if you are having a hard time harminizing the longer taper helps. I just got a boris flowmeter and it helps even more you can see if the needles are staying in sink before you notice your out of sink it cost me a piston last sommer later Charlie

 

[XtremeRcBoats]

Thanks Chalres, I think i got these from Andy but I'll check next time I'm at the shop. I've got a flow meter so setting the needles will be easy.

This is my first twin. Do you set the needles of the left and right engine at the same number. I remember that I once read the the left engine should be a tad richer. Is this correct?

 

[charles siler]

Inside motor is just a smidge but not at the cost of loosingthe motors harminization. you can play with mannadging cooling system eazyer keepit fat or you will burn a hole in one of thoughs fine motors pritty quick . A what props you going to run.later Charlie

 

[Tom Foley]

Boat should be a Missle . My Mac 84's in my Roadrunner Extreme 80 were great and very easy to tune . They revved to the moon with no mods and liked 64 mm - 1667"s with 5.6 cup from CMDI . Do not overload the engines with prop they need to rev and take advantage of the huge ports in the engines . Start them both blubbering rich on the stand and lean down till they will just barely clean out when throttle is held wide open . Then hit the water for a gallon of fuel (18 % oil at least ) and begin leaning down letting cool completely off ( 2 Fosters , St Pauli's ) between runs . I always ran non - remote needles as each engines requirements are sometimes different . Using this method my Macs lasted strong for about 4 years . Best of luck !!

 

[Tim Kish]

It's been a while but finally working on the twin again.

Got the engines in, put the rudder on,put the servo's in and added the watercooling tube.

Where do you put your 3rd needle? looking for a good location. I want to put the 2 needles inline and was thinking somewhere in the middle of the hull but there is not much space (see pic below)

What is a good pipe length to start with? (mac84's with parabolics) so that i can determine the pipe mounts.

Larger versions of the pictures can be found in my gallery

Thanks,

Great looking boat , should be a rocket.

Do yourself a favour and change the white plastic retainer on the carb linkages with some brass tubbing , the plastic doesn't last very long.

Tim

 

[XtremeRcBoats]

Tim do you mean the carb linkage at the carb, the dubro connectors or the white plastic inside the rc-box?

I put some flotation in the cowl, what is the best place to cut the vent holes in the cowl?? Do you have some example pictures of it?

 

[ALLAN YUEN]

Hi Paul Show pictures of my Ex - SGX Twin cowl (cut the vent holes) B) keep away water flow at carbs area

 

[Tim Kish]

Tim do you mean the carb linkage at the carb, the dubro connectors or the white plastic inside the rc-box?

I put some flotation in the cowl, what is the best place to cut the vent holes in the cowl?? Do you have some example pictures of it?

The Du Bro connectors at the carb , I have seen the white plastic break a number of times over the years on a few different people.
Tim

 

[Tom Foley]

Make a mold off that cowl before you cut it .

 

[XtremeRcBoats]

Tom, I made a mold of the cowl, the cowl of the picture is a copy.

Last weekend we had our annual fun run weekend and I ran the SGX for the first time. The sound of the singing MAC's was awesome. They were still very rich and pipes long (12,5") but i really like it

Movie of the first run:

http://www.youtube.com/watch?v=SnEaRqicW20

 

[ALLAN YUEN]

Hi Paul Look smooth best of props: ABC H-48 5.7 " cup. Will be very fast Good Luck!

 

[XtremeRcBoats]

Hi Allan, thanks for the props. I'll have to start looking for some props. I only got a twin 1667 set i bought a few years ago but don't know how much cup it has. Are 1667's too large?

 

[julianconde]

Its very rich and the pipes are very long but looks really good i like it as well.. you can use 1667 but you will have to cut them down but try them who knows they might work how you have them at the moment..

Julian