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View Full Version : snowmobilers or 2 stroke guys i need help..



rob0781
02-10-2005, 12:33 PM
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
02-10-2005, 01:47 PM
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
02-10-2005, 02:26 PM
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
02-10-2005, 09:30 PM
running 2 diff plugs is the dumbest thing i ever heard. run a b8es in both cyl and call it a done deal.................... :D

TimSr
02-10-2005, 09:57 PM
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
02-10-2005, 10:01 PM
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
02-11-2005, 05:40 AM
Just wondering...does the Safari have the same engine as a 80-82 SS Citation 400?

Dual carbs, oil injection...

TimSr
02-11-2005, 10:09 AM
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
02-11-2005, 01:11 PM
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
02-11-2005, 02:16 PM
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
02-11-2005, 02:39 PM
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/techinfo/spark_plugs/techtips.asp?nav=31000&country=US#

rob0781
02-11-2005, 06:05 PM
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
02-11-2005, 08:11 PM
ROFLMAO!!! I did not know that my spark plug was attached to my radiator!!! :rolleyes: :rolleyes: I guess I missed something somewhere!!!!

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


GREG

rob0781
02-11-2005, 08:30 PM
ROFLMAO!!! I did not know that my spark plug was attached to my radiator!!! :rolleyes: :rolleyes: 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
02-11-2005, 08:34 PM
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.

rob0781
02-11-2005, 08:41 PM
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.
UUUGGHHH i'm not even sure myself anymore,i here different things and find different answers when i search ,i'm confused... :wondering

atczack
02-11-2005, 08:46 PM
I think TimSr. and Oldschoolin86 just like to argue with each other! lol j/k

Billy Golightly
02-11-2005, 08:55 PM
Maybe after the debate rages on to about 5 pages I can email it to NGK with the main high points and ask them to explain :P

rob0781
02-11-2005, 09:39 PM
hahah ya i wonder if they'd reply..

hrc85250r
02-11-2005, 11:41 PM
you guys are crazy, unless the motor is modded, use exactly what the manual says, if you have a polaris almost all sleds have a decal under the hood by where the aircleaner touches the hood and it tells you all of the owner serviceable info...you wont burn up any cylinders if you take care of your sled and clean your carbs a couple times a season and dont hold it completely ridiculously wide open winding out like crazy across a lake for 10 mins....most of the blown cylinders i see happen because drunk morons crank them skyhigh until they pop, or people dont ever clean the carbs and one of the mains gets a little plugged and leans out and burns a hole in itself...


i had a 89 skidoo safari a couple years ago and beat the crap out of it, and kept my motor tuned up with stock-heat plugs, champions to be exact, and i cleaned the carbs every month or so and i never had a problem, never let me down, and started on the second pull every time no matter the temp....

OldSchoolin86
02-12-2005, 12:48 AM
Maybe after the debate rages on to about 5 pages I can email it to NGK with the main high points and ask them to explain :P
lol, I hope it doesn't get to be 5 pages. I learned in my last debate that if someone doesn't want to learn it's not worth debating with them.

Here's my last comments on this one. It's pretty clear what it does and how that insulator works. Put a piece of ceramic between two pieces of steel, heat one side and see what happens to the other. You guys gotta remember, tip temp is relative to combution chamber temp.

TimSr
02-12-2005, 01:44 AM
I learned in my last debate that if someone doesn't want to learn it's not worth debating with them.

Im open to learn, thats why Im still, waiting for an explanation. We agree with NGK, "Plugs dont generate heat, they can only remove it". Im with you so far, but after that Im lost. If somebody can explain to me why a plug that is such a wondeful heat exchanger and dissipater that it can cool something a hundred times its size, then why wouldnt sticking a few extra unconnected plugs in a head be the ultimate cooling system? And if they have to be connected to a coil to dissipate the heat, what does the electricity do that makes it such a powerful heat reducer? Im open to learn anything, but I need a simple logical explanation that makes sense. Ive explained my theory and Ill answer any questions about any of the specific principles Ive stated. If anybody can give me a logical explanation to my questions, I will accept the temperature regulation theory. I will accept anybody elses theory on anything if they can give a logical answer to my questions.

OldSchoolin86
02-12-2005, 02:24 AM
I will accept anybody elses theory on anything if they can give a logical answer to my questions.LMAO, you got logic in so many ways last time we debated it was silly. I'll still to my quoted statement.

TimSr
02-12-2005, 11:26 AM
LMAO, you got logic in so many ways last time we debated it was silly. I'll still to my quoted statement.

No actually when I proposed a little controlled experiment last time, that would test the opposing theory, it was met with a chuckle, glossed over, not explained or answered, and ignored just like this one.

OldSchoolin86
02-12-2005, 01:33 PM
No actually when I proposed a little controlled experiment last time, that would test the opposing theory, it was met with a chuckle, glossed over, not explained or answered, and ignored just like this one.
There was no theory, you just couldn't see the facts. This is why I don't see the point in debating. I'm not mad or anthing, it's just proven to be a battle not worth fighting. As far as your experiment, if you want to do it I'm not going to stop you.

rob0781
02-12-2005, 05:46 PM
Geez sorry guys this thread that was suppose to be a simple stupid question got a little to serious..lol

TimSr
02-12-2005, 08:28 PM
Geez sorry guys this thread that was suppose to be a simple stupid question got a little to serious..lol

Im sorry I hijacked your thread. Most motors have a range, usually one hotter, or one colder then stock, but check your manual to verify for your machine. Then experiment and use what works best within the range they give you.

rob0781
02-12-2005, 11:55 PM
no problem,i'm just trying to learn about 2 strokes,i'm a little confused but with more research i'll be good to go,i haven't got a manual for the sled,i'm gonna try running 2 eights,i been thinkin i got the sled 3-4 days ago and since then it was 0c to -3c so it's been kinda warm,tonight i was out in the trails and it was -11c at that time and the machine seemed like it ran better,seemed to be a bit quicker too...could weather cause plugs to foul,and if so i wonder if jetting could be the culprit?

TimSr
02-13-2005, 02:47 AM
Its very tricky jetting for cold weather. A cold motor runs very rich, which is why you see so many fouled plugs in the winter during initial warmup. After your motor is warmed up though, the cold air will make it run leaner. Many people make the mistake of jetting leaner because of fouled plugs, and they have a problem when it warms up of running too lean. The best thing is to come up with a warmup procedure that works best for your machine. Dont rev it up when its cold. You are feeding it a lot more than it can digest when you do this. Start it, let it idle and give it very light, 1/8th throttle revs if necessary to keep it running, until it warms up, and then rev it up to clean it out.

bigredhead
02-13-2005, 10:15 AM
ok.. i know i should just turn around and walk away.. but here's another opinion on the plug thing.

a longer tip would sit further into the cylinder and gets hit with bigger rush of fuel/air from the carb resulting it a difference in operating temps. ( THe whole thing about the cooling effect )

A shorter plug tip would sit higher up on the cylinder head resulting in a different flow of air from the intake and exhaust valves and thus affect the way it burns fuel and how efficiently it does it.

depending on the motor/head a longer or shorder plug tip ( hotter or colder ) works better or worse depending on the application it's subject to. High RPM's = more air .. less RPM's less volume of air and different loads on the tip.

Ever see ambers glow bright red when you blow on them ? and dim when you stop ? same idea.. you strive for an optimal temp to burn all the fuel in the cylinder as much as possible, without causing deposits/carbon.. not not too hot that it burns things up.

The incoming air/fuel from the carb is what does the cooling you guys are refering to, i personally think, not the plug itself.

rob0781
02-15-2005, 12:15 AM
*UPDATE*

Well i ran the sled for a good part of the day today,put 120km on it and i was running br8es in each side it fouled br9's whicj is stock br8 is a step highter but it ran perfect all day,i was out again after dark it was gettin cold and it works great in the cold,but i guess being fan cooled the cold help...so regardless what a plug does heat wise,i'm just happy she's runnin good..Thanks for all the replies and theories..Rob

rustbucket
02-16-2005, 09:59 PM
you guys are way off as a big snowmobile man heres the reason why they run different plugs. the fan is next to the 1 cylinder keeping it at a colder temp than #2 so it doesn't burn all the fuel so number two sucks its fuel in plus the extra and it kills the plug if its alot extra so if the cylinder is burning a little "hotter" it will burn all the fuel and not kill the plug.

OldSchoolin86
02-16-2005, 10:26 PM
you guys are way off as a big snowmobile man heres the reason why they run different plugs. the fan is next to the 1 cylinder keeping it at a colder temp than #2 so it doesn't burn all the fuel so number two sucks its fuel in plus the extra and it kills the plug if its alot extra so if the cylinder is burning a little "hotter" it will burn all the fuel and not kill the plug.
LMAO, I already kind of said this. Your wrong about the other cylinder taking in more but it would burn differently.

rob0781
02-18-2005, 09:37 PM
you guys are way off as a big snowmobile man heres the reason why they run different plugs. the fan is next to the 1 cylinder keeping it at a colder temp than #2 so it doesn't burn all the fuel so number two sucks its fuel in plus the extra and it kills the plug if its alot extra so if the cylinder is burning a little "hotter" it will burn all the fuel and not kill the plug.
this was what my understanding was.