sg21

[mtruex]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

 

[Rokieboater]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

I run the same combo and I ran the pipe a little longer to the start of the back cone than the previous pipe. ab21 pipe gives off a different sound but ran the same speed. Same prop with a little more pitch was possible with this pipe. No plug problem. Check your bearings and fuel lines/remote needle for blockage.

Robert

 

[mtruex]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

I run the same combo and I ran the pipe a little longer to the start of the back cone than the previous pipe. ab21 pipe gives off a different sound but ran the same speed. Same prop with a little more pitch was possible with this pipe. No plug problem. Check your bearings and fuel lines/remote needle for blockage.

Robert

the 7 1/4 i measured was to the start of the flat in the center of the pipe, or the end of the front cone..what prop do you run?

 

[mtruex]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

I run the same combo and I ran the pipe a little longer to the start of the back cone than the previous pipe. ab21 pipe gives off a different sound but ran the same speed. Same prop with a little more pitch was possible with this pipe. No plug problem. Check your bearings and fuel lines/remote needle for blockage.

Robert

the 7 1/4 i measured was to the start of the flat in the center of the pipe, or the end of the front cone..

 

[camaroboy383]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

I run the same combo and I ran the pipe a little longer to the start of the back cone than the previous pipe. ab21 pipe gives off a different sound but ran the same speed. Same prop with a little more pitch was possible with this pipe. No plug problem. Check your bearings and fuel lines/remote needle for blockage.

Robert

the 7 1/4 i measured was to the start of the flat in the center of the pipe, or the end of the front cone..

sounds like a lean condition to me....check your plug face or top of the piston with a magnifier glass for small pitting or speckling,,,this is typically detonation,,,but on the other hand the 2 burned up plugs in a row will give you a little speckle affect..... correct me if im wrong,,,but the speckling would be in the center or more towards the exhaust port side of the piston...this would defenitely be a lean condition...like stated above,,,check the crank bearings and fuel lines...if those check out o.k then fatten up the needle alot then run it and see if it burns them up still...

probably isnt as fast as it should be for this reason....

alden

 

[AndyBrown]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

Martin,

Do you know how much cup is in the 1445?

Andy

 

[mtruex]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

Martin,

Do you know how much cup is in the 1445?

Andy

andy,

i cant remember,3.4 maybe.. i got it from you though..if i fatten it up it wont burn plugs ,but it doesnt rpm like it should with a pretty short pipe,no matter the needle.thats what i am trying to figure out ,sorry for the confusion..i know making it too lean is causing the plugs to burn out i just cant see why it wont sing..has plenty of torque and midrange..

.the fuel lines and 3rd channel needle are good to go..i have a new set of bearings for it that i will put in it though..thanks for the help..any other suggestions would be great..MT

 

[AndyBrown]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

Martin,

Do you know how much cup is in the 1445?

Andy

andy,

i cant remember,3.4 maybe.. i got it from you though..if i fatten it up it wont burn plugs ,but it doesnt rpm like it should with a pretty short pipe,no matter the needle.thats what i am trying to figure out ,sorry for the confusion..i know making it too lean is causing the plugs to burn out i just cant see why it wont sing..has plenty of torque and midrange..

.the fuel lines and 3rd channel needle are good to go..i have a new set of bearings for it that i will put in it though..thanks for the help..any other suggestions would be great..MT

Sounds like not enough load. Could use a bigger prop for more load, but the best way would be to stick with the 1445 3.4" and shorten the pipe. I designd that pipe to work at a shorter length. I'll have to check my notes to see how your 7 1/4" referance point compares.

 

[mtruex]

ran my sg21 today with mac21, ab21xt pipe at 7 1/4 and 1445 and burned two plugs (65% nitro) . i have not ran it since the weather got warm but when it was cold it had no trouble burning plugs..at the same time it is not as fast as i think it should be ,and does not rev like i think it should with this setup..my thought is that im leaning it out to try and get it to sing but i dont think the motor has enough load on it..little longer pipe and more prop maybe? any help would be appreciated thanks guys, MT

Martin,

Do you know how much cup is in the 1445?

Andy

andy,

i cant remember,3.4 maybe.. i got it from you though..if i fatten it up it wont burn plugs ,but it doesnt rpm like it should with a pretty short pipe,no matter the needle.thats what i am trying to figure out ,sorry for the confusion..i know making it too lean is causing the plugs to burn out i just cant see why it wont sing..has plenty of torque and midrange..

.the fuel lines and 3rd channel needle are good to go..i have a new set of bearings for it that i will put in it though..thanks for the help..any other suggestions would be great..MT

Sounds like not enough load. Could use a bigger prop for more load, but the best way would be to stick with the 1445 3.4" and shorten the pipe. I designd that pipe to work at a shorter length. I'll have to check my notes to see how your 7 1/4" referance point compares.

the pipe is slid way over the header and is about about 1/2 inch from the header flange , if that helps..thanks MT

 

[Buckshot]

I run the same pipe and motor in an SGX-1 boat.

Donna told me to measure from the plug to the rear of the flat band/start of the rear cone and set it at 8.25". I did and it is a rocket. If the flat band in the pipe is 1" than it sounds like your pipe is set to a correct lenght. I heat race this boat with a 1445 @ 3.5" cup. It runs well with good R's on 65% nitro.

What is you head clearance set at?

Regards,

-Buck-

 

[mtruex]

I run the same pipe and motor in an SGX-1 boat.Donna told me to measure from the plug to the rear of the flat band/start of the rear cone and set it at 8.25". I did and it is a rocket. If the flat band in the pipe is 1" than it sounds like your pipe is set to a correct lenght. I heat race this boat with a 1445 @ 3.5" cup. It runs well with good R's on 65% nitro.

What is you head clearance set at?

Regards,

-Buck-

buck,

head clearance is at .006 and i think the band is a little longer than 1 inch, i dont have the boat here with me to check but i think its a little bit longer than yous not much though..thanks,MT

 

[Topfuel666]

I run the same pipe and motor in an SGX-1 boat.Donna told me to measure from the plug to the rear of the flat band/start of the rear cone and set it at 8.25". I did and it is a rocket. If the flat band in the pipe is 1" than it sounds like your pipe is set to a correct lenght. I heat race this boat with a 1445 @ 3.5" cup. It runs well with good R's on 65% nitro.

What is you head clearance set at?

Regards,

-Buck-

Buck,

I have my pipe also set at 8.25" to the rear of the flat. What are running the the 45XT pipe at?

Thanks,

Bill

 

[dwb2620]

I run the same pipe and motor in an SGX-1 boat.Donna told me to measure from the plug to the rear of the flat band/start of the rear cone and set it at 8.25". I did and it is a rocket. If the flat band in the pipe is 1" than it sounds like your pipe is set to a correct lenght. I heat race this boat with a 1445 @ 3.5" cup. It runs well with good R's on 65% nitro.

What is you head clearance set at?

Regards,

-Buck-

Hey Buckshot,

Where do you get your 65% nitro at?

David

 

[Brad Christy]

Mtruex,

Take a look at your bowl volume. Everything else sounds about right, so this might be it. Get ahold of a .5cc insulin syringe, fill it with isopropyl alcohol EXACTLY to the .5cc mark and then fill the bowl until it is just level with the squishband. Mine checks about .17-.18cc and I go through plugs like water. It's just about like what you describe: It'll run all day long on one plug as along as I run it so rich it won't get over about 20K, lean it down so that is starts singing, and pop goes the plug. I'm going to open mine up to about .20cc and see what it does. Try adding an extra copper washer or two under the plug and see if it gets any better.

BTW, other props to try are the H-6, cupped to about 3.6", or the H-10 stock pitch, cut down to 44-45mm, both de-tongued.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

 

[mtruex]

Mtruex,
Take a look at your bowl volume. Everything else sounds about right, so this might be it. Get ahold of a .5cc insulin syringe, fill it with isopropyl alcohol EXACTLY to the .5cc mark and then fill the bowl until it is just level with the squishband. Mine checks about .17-.18cc and I go through plugs like water. It's just about like what you describe: It'll run all day long on one plug as along as I run it so rich it won't get over about 20K, lean it down so that is starts singing, and pop goes the plug. I'm going to open mine up to about .20cc and see what it does. Try adding an extra copper washer or two under the plug and see if it gets any better.

BTW, other props to try are the H-6, cupped to about 3.6", or the H-10 stock pitch, cut down to 44-45mm, both de-tongued.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

thanks for the info brad..and everyone else, hope to have it ironed out in a few late nights..

 

[shoboat]

Martin,

What is your exhaust timing in that motor? 178*? OPS 3280 Pipe?

You may need a little more sponson angle in your boat.

Keep Testing,

Mark Sholund

 

[mtruex]

Martin,
What is your exhaust timing in that motor? 178*? OPS 3280 Pipe?

You may need a little more sponson angle in your boat.

Keep Testing,

Mark Sholund

mark,

i have not measured it yet, i plan on putting it in the eap this week..pipe is ab21xt i have read where some guys have had success with shiming the front boom up some, i will try it once i get the motor sorted out..i forgot to mention i put the cmb piston/sleeve it it, there was a thread about it that marty davis started a while back, he put them in his motors also..maybe he will chime in..

 

[Marty Davis]

Martin,
What is your exhaust timing in that motor? 178*? OPS 3280 Pipe?

You may need a little more sponson angle in your boat.

Keep Testing,

Mark Sholund

mark,

i have not measured it yet, i plan on putting it in the eap this week..pipe is ab21xt i have read where some guys have had success with shiming the front boom up some, i will try it once i get the motor sorted out..i forgot to mention i put the cmb piston/sleeve it it, there was a thread about it that marty davis started a while back, he put them in his motors also..maybe he will chime in..

Martin:

Invitation still stands. Load up Aric and come down on your off weekend (what off weekend) and we will get it running WELL.

I am running that liner and piston now in my MAC, but the current version of the CMB is MUCH more powerful. I am not able to run the same prop that I can with the best engine, but it is running fairly well.

I would suggest that you use the 3280 set at 8 1/2" and the stinger reduced to .282". That is a system that I know well and one that works very well.

As for the plug burning, everyone that I know who is running super well will burn plugs when the needle is crisp. I burn them, and hate it with the price of plugs. I am currently working on a solution to the plug burning. Probably won't be successful, as I have never been able to cure it completely in the past.

Marty Davis

 

[shoboat]

Marty,

Our plug burning is getting much better, now that we have switched

to O'Donnell Turbo plugs. We run on the rich side of the needle,but

they seem to hold up much better.

Have Fun Testing,

Mark Sholund

 

[mtruex]

Martin,
What is your exhaust timing in that motor? 178*? OPS 3280 Pipe?

You may need a little more sponson angle in your boat.

Keep Testing,

Mark Sholund

mark,

i have not measured it yet, i plan on putting it in the eap this week..pipe is ab21xt i have read where some guys have had success with shiming the front boom up some, i will try it once i get the motor sorted out..i forgot to mention i put the cmb piston/sleeve it it, there was a thread about it that marty davis started a while back, he put them in his motors also..maybe he will chime in..

Martin:

Invitation still stands. Load up Aric and come down on your off weekend (what off weekend) and we will get it running WELL.

I am running that liner and piston now in my MAC, but the current version of the CMB is MUCH more powerful. I am not able to run the same prop that I can with the best engine, but it is running fairly well.

I would suggest that you use the 3280 set at 8 1/2" and the stinger reduced to .282". That is a system that I know well and one that works very well.

As for the plug burning, everyone that I know who is running super well will burn plugs when the needle is crisp. I do and hate it with the price of plugs. I am currently working on a solution to the plug burning. Probably won

t be successful, as I have never been able to cure it completely.

Marty Davis

one of these days marty!

well i got it running well today, i feel like an idiot after what it was..apparently it was late one night when i checked the head for detonation after running it in , well i left out a few shims and my clearance was only .003 ooops! i fixed that, cleaned up the plug pieces from the button and ran it.gave it a warm up lap then started leaning it down on each straight, it was just starting to sing and my remote batt started beeping and i brought it in..checked plug nice and shiny still, good news...

my pipe was right at 8 1/4 to the rear cone as suggested with the 1445. should be good to go now.. anyway thanks for the help guys

cya Martin