# Spark Plug Upgrade, racing spark plug, is this behavior expected?



## superedge88 (Nov 26, 2013)

I have read on more than a few websites that with the racing spark plug AR3910X Autolite you can get "about 3/4 HP more" on the GX160 motor that is on my Honda HS621.
AR3910X Spark Plug Honda GX160 / GX200 and Titan clone engines
So I thought "what the heck, why not try it!"
I installed the new spark plug, and the snowblower will not run without being half choked. It surges and the dies if I take it completely off choke. Is this what I should expect with higher compression and more spark with the upgraded spark plug? I can easily go back to the stock spark plug, but I would love to have more HP if it is possible. 12v electric is more in my wheel house, so this is over my head. Educate me?


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## brickcity (Jan 23, 2014)

3/4 more horsepower with a sparkplug?
must be true, you read it on the internet


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## Normex (Feb 21, 2014)

superedge88 said:


> Is this what I should expect with higher compression and more spark with the upgraded spark plug? I can easily go back to the stock spark plug, but I would love to have more HP if it is possible. 12v electric is more in my wheel house, so this is over my head. Educate me?


Hi Superedge, I fail to see how a spark plug would give a higher compression but the higher spark would be more than welcomed, I think you should put back the old one and see if your engine reacts the same.
Just a suggestion, Good Luck

Ok I should have read link but it must be minimal with just the spark plug.


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## db9938 (Nov 17, 2013)

My guess, those machines were also over jetted. I still find it highly suspect though.


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## superedge88 (Nov 26, 2013)

brickcity said:


> 3/4 more horsepower with a sparkplug?
> must be true, you read it on the internet


Such a helpful post, enjoy your higher post count.


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## superedge88 (Nov 26, 2013)

Normex said:


> Hi Superedge, I fail to see how a spark plug would give a higher compression but the higher spark would be more than welcomed, I think you should put back the old one and see if your engine reacts the same.
> Just a suggestion, Good Luck
> 
> Ok I should have read link but it must be minimal with just the spark plug.


Thanks, I can definitely go back to the original spark plug, but boy is it a pain trying to get to the spark plug on this machine! This spark plug was just 7 dollars at my local auto store. I've lost money on much more foolish endeavors, I couldn't resist trying it out.


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## 43128 (Feb 14, 2014)

its an autolite and an american designed plug in a japanese designed and built engine. did you seriously expect it to work? put a new bpr6es in and stop messing with it


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## detdrbuzzard (Jan 20, 2012)

why stop with a plug that only gives you a 3/4hp increase when there is an old post about a plug that gives you a 7hp increase 
seriously though a plug by itself isn't going to do anything for an hp increase without other mods being done to the engine and 3600rpm isn't exactly a high rpm motor


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## 43128 (Feb 14, 2014)

the only thing a spark plugs ever improves for me is just running in general. champion plugs suck once you have tried an ngk


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## Freezn (Mar 1, 2014)

First place I would start for more power would be to increase the engine speed by bumping up the RPM's. I would also consider re-jetting the carb. Given an OEM HS621 carb goes for around $70 bucks, I would probably leave the original carb alone and pick-up an aftermarket carb and play around with the jetting for more power.


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## HJames (Oct 28, 2013)

I'm not sure if you'll get more horsepower, but if you open the gap somewhere between .35-.40 and index the plug you might have better luck with it.


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## UNDERTAKER (Dec 30, 2013)

Never heard that theory before. and that is all I am saying on that 1.


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## Shryp (Jan 1, 2011)

Sounds good in theory. It says the plug is longer than the stock plug. That means there is less air volume in the cylinder so that should give higher compression and HP. Isn't that the same premise behind milling the head or going with a low profile head gasket?

Are you going to notice a difference? In your case it sounds like you did.


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## GustoGuy (Nov 19, 2012)

The racing Sparkplug has an open center electrode and is slightly longer than the stock plug. Also it has a shallower depth on the insulator so it is suppose to reduce the volume of the combustion chamber by a few CC to slightly increase compresslon. I am running the Ngk plug in all of mine.


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## micah68kj (Oct 8, 2011)

If it ain't broke don't fix it.


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## pfn (Dec 24, 2010)

From racing go karts I believe plugs make a difference but how much I have no clue. It seemed that everyone in a particular class ran the same plug but that may have just be "herd mentally". It may have just been fashionable or the racing plug may have been a bit more dependable. Who knows? 
To increase compression I agree with Shryp. Increased compression can only, as far as I know, be accomplished with decreased combustion chamber volume. I can't se a plug affecting that significantly.


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## superedge88 (Nov 26, 2013)

I do appreciate the constructive replies that I have received in this thread, as for the hostile replies... I'll refrain from typing what I really want to say.
It was definitely worth a try, sure it didn't work well at all, but what did I really have to lose? If we don't try new things every once in a while then we become stagnant. I constantly want to learn more and try new things, it's the reason that I tried LEDs on my snowblower, and I think that worked out pretty well!!!
Thanks again guys, I'll be sticking to the stock NGK plug!


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## Normex (Feb 21, 2014)

superedge88 said:


> I do appreciate the constructive replies that I have received in this thread, as for the hostile replies... I'll refrain from typing what I really want to say.
> It was definitely worth a try, sure it didn't work well at all, but what did I really have to lose? If we don't try new things every once in a while then we become stagnant. I constantly want to learn more and try new things, it's the reason that I tried LEDs on my snowblower, and I think that worked out pretty well!!!
> Thanks again guys, I'll be sticking to the stock NGK plug!


 I agree entirely with you Superedge, we don't often think in "no pain no gain" terms or "thinking outside the box" and I strive to think in those terms but of course the ideas are "one in a million". 
Ok enough already of these " great ideas come from great minds".
(just trying to put some irony as it helps sometimes)


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