Poor man's advancer? Deep thoughts...

[thirdman]

Correct me if I'm wrong, but if you wanted to advance your timing quickly and cheaply, couldn't you just run one step hotter spark plugs?  The priniciple being that a hotter plug will ignite the fuel/air mixture slightly sooner, thereby having the same effect as advancing the timing a little bit, right?

Just a thought...

[pandy]

I just tried running hotter plugs, and my bike ran like caca. I'm too lazy to make other adjustments, so the old plugs are back in 'til I buy new of the same.

pandy

[Roadstergal]

Ignition advance is actually making the plug fire sooner.  The plug will fire at the same time, it'll just be hotter than the engine was designed for... I severly doubt it will work as you say.

[The Buddha]

OK advance does make it spark sooner, but only till about 4K, over that advance is controlled by the black box and maxes out ...
Hotter spark plugs do not have anything to do with the power or the electrical nature of the spark ... The hotter plug will reach a higher temperature after the motor warms up. Spark plugs get splattered with carbon and gasoline, and they need temperature for burning up that before the time comes to spark ... else spark gets shorted out and the bike doesn't fire ... Sparkies dissipate heat into the head, and the hotter plug has a longer path for that heat dissipation, so it will retain more of the combustion heat. Now put in too hot a plug and it will made a hot spot and detonate ... too cold and it will get killed by carbon and gas ... so you need to get the right heat range plug.
Having said that ... of late I am sorta disappointed in the quality of NGK's, dismayed by the black Autolites and have gone to Champions. I believe NGK's may just run a shade colder than they should, because the Virago with rejetted carbs and pipe seems to run great on 1 step hotter NGK's. Maybe jetting a GS might call for Champions or 1 level hotter NGK's ... Not tried it. But just a thought. Stock GS and stock plugs should be fine.
If you want more power in the spark you need to start with the plug wires, coils, and then move on to other electrics.
Cool.
Srinath.

[thirdman]

I understand that the 'temp' of a spark plug doesn't have anything to do with the timing of the spark, i was addressing the speed and efficiency of the the actual ignition and burn of the fuel/air mix.

My assumption was that a hotter spark plug will effectively heat the fuel/air mix in the cylinder.  Shouldn't a hotter f/a mix will ignite quicker than a colder f/a mix?  Also,  it seems that the flame front will travel faster through a hot mix than a slow mix.  Faster ignition and burn means that the point of maximum pressure in the cylinder will occur sooner...  which is all you are trying to accomplish with advancing the ignition.

Now I have no real science to back this up, just anectodal evidence that I have hear here and there.  Ignore me if I am full of baloney.

[davipu]

you are full of baloney, you need a memory dump and a healthy dose of gs wisdom.  now go bang head against wall.

hotter spark plugs have a increased resistance built in so that the spark is more intense.  kinda like the difference between a 60 watt light bulb and a 100 watt one.  the point of havign hotter plugs than stock whould be if you raised the compression to the point whare you were havign iginition problems from running higher octane fuels.   they have nothign to do with heating A/F mixtures, now go back to banging head against wall. :mrgreen:

[Phaedrus]

I know next to nothing but I'll offer some n00b insight. Take it for what it is worth. (Not much..)

I used to have a moderately modified Dodge Dakota, and we had (well, it is still there) a community forum much like this one for our GS's   . One of the common mods guys with the old school LA-based engines (3.9/5.2/5.9 engines) would do after doing a few other mods would be to run one step COOLER spark plugs. Runing them one range cooler than stock made the engine run cooler. It went well with a lower thermostat (180 instead of stock 195).

I realize that cycle engines and truck engines are different, and the truck was liquid cooled and these are air cooled. Etc. etc. etc.

But isn't heat the enemy with an engine? Don't you want it to "run as COOL AS POSSIBLE but no cooler!"

Davipu, feel free to tell me I am full of boloney too, because I probably am  :lol:

[thirdman]

you are full of baloney,

Um... I think you need to reread roadstergal's and seshadri_srinath's responses...

[davipu]

Srinath is full of    and Roadstergal well she's a girl, you can't believe girls when they tell you mechanical things.  :mrgreen:    





and your still full of  

[thirdman]

and your still full of  

Well, at least your .sig is accurate...

[pandy]

*ding* *ding*

round over...to your corners, gentlemen....  

pandy  :mrgreen:

[davipu]

if you want to play ring girl you better be in a bikini.

[pandy]

I will if you will!  

pandy  

[davipu]

you really don't want to see me in a bikini. you thought Srinath in a thong was wrong, this is a whole new level.

[pandy]

Then no deal!  :dunno:

pandy

[The Buddha]

I understand that the 'temp' of a spark plug doesn't have anything to do with the timing of the spark, i was addressing the speed and efficiency of the the actual ignition and burn of the fuel/air mix.

My assumption was that a hotter spark plug will effectively heat the fuel/air mix in the cylinder.  Shouldn't a hotter f/a mix will ignite quicker than a colder f/a mix?  Also,  it seems that the flame front will travel faster through a hot mix than a slow mix.  Faster ignition and burn means that the point of maximum pressure in the cylinder will occur sooner...  which is all you are trying to accomplish with advancing the ignition.

Now I have no real science to back this up, just anectodal evidence that I have hear here and there.  Ignore me if I am full of baloney.

Hotter mix what the ...
OK guys this is so freaking wrong ...
OK Here it is. And its available on several websites ...
The job of the spark plug is not to heat your mix, or to make your mix burn faster (which BTW is called detonation) ... the heat range of the spark plug has nothing to do with the spark power or anythign. The heat range of a plug is the temperature it reaches at steady state running. That is it. If your plugs are getting shorted out with carbon and gas and hence spark is getting killed, your motor could use a hotter plug whihc will burn itself clean ... that is it. That info is available on several websites (Including Bosch and Autolite). 1 step colder plug is usually a mod if you have leaned out your mix a shade. Leaner mix sometimes make more power. Hotter is when you have possibly richened your mix ... but do not change to hotter or colder just because of that. You do not want any hotter than it needs to run, and really having it colder than manufacturer recomendation is also not needed. I have checked it out well ... if you need - please do the needed research before theorising or fine I dont care its your bike.
Cool.
Srinath.

[The Buddha]

Yea I also once saw (here I think) someone posted about a plug that will make more power ... it effectively has longer threads ... so sits deeper in your chamber ... Eating up more volume ... See at the top of the stroke the volume of the chamber is about 25CC per chamber, take up 2-3 CC and its a 10% bump in compression. So you'd have a motor that has higher compression and hence more power ... down side ... it might get hit by the piston ... or the valve depending on how much interference it has.
Cool.
Srinath.

[thirdman]

OK guys this is so freaking wrong ... .

Dude... chill... I was just asking a question with the hope of an engaging intelligent discourse.  

Guess this is the wrong forum for that.

(p.s. never did get a response to the rate of burn question.  I was expecting the coversation to turn to the physics and chemistry of fuel burn, hot vs. cold air intake and engine cooling methods... water vs. air vs. oil, and the pros/cons of large engine temperature variation and optimal operating temps.  Moot now, I give up.  You win.    )

[Phaedrus]

One thing GStwin is not good for is intelligent discussion.  :lol:  Seriously, I've noticed anything that is too abstract, or does not flow along the lines of the status quo, are often bombarded with negativity.

I don't think that was the case here, I think it was just a miscommunication. They were thinking about the practice and execution of the plugs as opposed to the theory. The "whats" instead of "whys" perhaps.  :dunno:

[thirdman]

My original question was not phrased as well as it could have been, that is true.   My feelings aren't too hurt...  nobody insulted my mother or said I was ugly or anything like that.  

I'll wait a couple weeks and repost a more intelligently thought out question and see what happens.