snowmobilers or 2 stroke guys i need help..

[rob0781]

Ok on the safari i picked up i was told to run a colder plug in the far cylinder from the fan,so anyhow i'm kinda confused the clutch side has a br7es and the fan side has a br8es i bought a pack of br7es,br8es and a pack of br9es si=o i'm wondering what would be a good combination to run?Is br7es hotter or colder then a br9es?I'm really confused,the guy i got it from told me to run it with differnt heat ranges he says it works better so i'm guessing the br7es is cooler cause thats how he's got it set up...any help please i heard NGK and champion plugs are complete oposite heat ranges i have NGK's any help please..

[83200e]

Hey Rob,
Don't know anything about mixing heat ranges but I do know the ngks are numbered with the coldest being the highest number,and your right, the champions are the exact opposite.

[rob0781]

cool thanks for the response i called the dealer to see what they had to say they told me that br9es is what the manual says for the sled and those are colder plugs,before i just swapped the plugs there was a br7 in one and a br8 in the other so with both br9es's in i think i'm safe those being colder plugs..

[G-MAN-1]

running 2 diff plugs is the dumbest thing i ever heard. run a b8es in both cyl and call it a done deal....................

[TimSr]

Its not as dumb as it sounds. I dont know anything about snomobiles, but if you run twin cylinders from a single carb, like a 2 into carb kit for a Banshee changing plug heat ranges is the only way to match them up, aside from some skilled porting. On the stock twin carb setup, it is not unusual to have different main jets in each carb. Its not unusual for them to have slightly different burn rates in each cylinder.

Just taking a wild guess here, but Id imagine the guy told you to do that because one cylinder runs a little richer than the other, and thats why he runs a hotter plug in it.

[OldSchoolin86]

Heat ranges don't change spark, they change tip temp. He might have known that one cylinder was hotter then the other and wanted to equal out the tip temps.

[TTribaLL]

Just wondering...does the Safari have the same engine as a 80-82 SS Citation 400?

Dual carbs, oil injection...

[TimSr]

Heat ranges don't change spark, they change tip temp. He might have known that one cylinder was hotter then the other and wanted to equal out the tip temps.

Yes, heat range is talking about the temp of the tip, and a hotter tip has similar effect to running leaner. How would you know one cylinder is a different temp, than the other? Does colder one run richer, or does the richer one run colder? A plug's heat range does not directly control temp of the cylinder. A hotter plug creates a leaner burn condition, which usually raises the temp. I agree that hot or cold is only referring to the plug tip. It should not be thought of as a thermostat to cylinder temp, because the plug it self cannot directly raise cylinder temp. You dont adjust plugs to get a desired temperature. You adjust them to get a proper burn rate, which will result in an acceptable temperature.

[OldSchoolin86]

It should not be thought of as a thermostat to cylinder temp, because the plug it self cannot directly raise cylinder temp. You dont adjust plugs to get a desired temperature. You adjust them to get a proper burn rate, which will result in an acceptable temperature.

Ouch, you couldn't be more wrong Tim. Half the reason you select a plug is to adjust temperature.

A spark plug has two jobs:
1. To ignite the air/fuel mixture
2. To remove heat from the combustion chamber

Here's an explination strait from NGK:

It is important to remember that spark plugs do not create heat, they can only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat.

The rate of heat transfer is determined by:

The insulator nose length
Gas volume around the insulator nose
The materials/construction of the center electrode and porcelain insulator

A spark plug's heat range has no relationship to the actual voltage transferred though the spark plug. Rather, the heat range is a measure of the spark plug's ability to remove heat from the combustion chamber. The heat range measurement is determined by several factors; the length of the ceramic center insulator nose and its' ability to absorb and transfer combustion heat, the material composition of the insulator and center electrode material.

It's already been stated that the fan hit's one side of the motor first. If the cylinder furthest from the fan ran lean it could be a sign that it was too hot and a different heat rage plug was needed.

[TimSr]

I totally disgree with your interpretation of NGk's statement. They are talking about dissipating heat from the plug tip, not about cooling the motor. The further the center electrode goes into the cylinder and away from the heat sink (the head that its screwed into) the hotter it gets. A hotter plug is most easily identified by how far the center electrode and insulater sticks out. Compare a b7es, b8es, and b9es, and its the only easily visible way you can tell them apart.

Think about this. If changing the center electrode of a plug has so much power to cool the engine, why not just drill and thread a couple more dummy plugs into your head to keep the engine really cool in place of cooling fins, or a liquid cooling jacket? Why wont it work? Can you make the case that appying high voltage to it, somehow gives it heat dissipating properties beyond a spark plug sticking in there without a wire on it? In the 70's a lot of dirt bikes had two spark plug holes in the head. "It is important to remember that spark plugs do not create heat, they can only remove heat" were NGK's words that you have used. Adding a millimeter to the length of the center electrode is not going to change heat dissipation in a motor and cool it down, but having it sticking a millimeter farther into the "furnace" and away from the cooling source (the head) will significantly increase temp of the plug's center electrode tip.

If there is a way to dissipate huge amounts of overall engine heat through a tiny electrode change, Im sure lots of engineers who design cooling systems would like to get their hands on it.

[OldSchoolin86]

I totally disgree with your interpretation of NGk's statement. They are talking about dissipating heat from the plug tip, not about cooling the motor. The further the center electrode goes into the cylinder and away from the heat sink (the head that its screwed into) the hotter it gets. A hotter plug is most easily identified by how far the center electrode and insulater sticks out. Compare a b7es, b8es, and b9es, and its the only easily visible way you can tell them apart.

Think about this. If changing the center electrode of a plug has so much power to cool the engine, why not just drill and thread a couple more dummy plugs into your head to keep the engine really cool in place of cooling fins, or a liquid cooling jacket? Why wont it work? Can you make the case that appying high voltage to it, somehow gives it heat dissipating properties beyond a spark plug sticking in there without a wire on it? In the 70's a lot of dirt bikes had two spark plug holes in the head. "It is important to remember that spark plugs do not create heat, they can only remove heat" were NGK's words that you have used. Adding a millimeter to the length of the center electrode is not going to change heat dissipation in a motor and cool it down, but having it sticking a millimeter farther into the "furnace" and away from the cooling source (the head) will significantly increase temp of the plug's center electrode tip.

If there is a way to dissipate huge amounts of overall engine heat through a tiny electrode change, Im sure lots of engineers who design cooling systems would like to get their hands on it.

LMAO, Tim read it again. I think NGK said it best:

Spark plugs are one of the most misunderstood components of an engine.

Here's a link to the article:
http://www.ngksparkplugs.com/techinf...00&country=US#

[rob0781]

Wow!!! thanks for the replies,i just got home and had lot of reading..I suppose i asked a question but i really didn't give as much detail as i should have so here goes..

the sled has a 377cc engine fan cooled ,it is a single carb and is oil injected ,when i pull the br7 and match it with the br8 they appear to be running the same if i run two br9's which is a stock plug for that sled the fan side seems to still run fine but the clutch side is richer as far as i can tell and that seems to be whats fouling it...I was researchin some more and i was told that if the clutch seal it bad it could be sucking air on that side,also i did compression tests on each cylinder and they are both 135psi...Thanks for the help,Rob

[md1985250r]

ROFLMAO!!! I did not know that my spark plug was attached to my radiator!!! I guess I missed something somewhere!!!!

Will someone please tell me how to connect my spark plug to my radiator???


GREG

[rob0781]

ROFLMAO!!! I did not know that my spark plug was attached to my radiator!!! I guess I missed something somewhere!!!!

Will someone please tell me how to connect my spark plug to my radiator???


GREG

you must've misundestood,what we mean is plugs come in fifferent heat ranges some burn hoter some colder.

[Billy Golightly]

The NGK article says the plug acts like a heat exhanger to get the heat from the combustion area into the engines cooling system, which I think is what Greg was refering to. I'm interested in understanding how a spark plug acts as a heat exchanger myself.