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Discussion Starter #1
Has anybody with an ARIENS wirth the 420 Re-jetted the carb.?

Youyr input is appreciated!
 

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Ive been trying to find info out myself
I found a high altitude jet today for the 414cc which could be used to drill out as a guinea pig
tried to find out today if the jets for the 414cc and the 420cc is the same no luck
my jet has a 113 on it have you had yours apart to look?
LCT Engine Part # 41450501 JET-HIGH ALTITUDE
As you go up in altitude air becomes thinner and will make an engine run rich, a high altitude jet will lean the mixture out even more at sea level.
 

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As you go up in altitude air becomes thinner and will make an engine run rich, a high altitude jet will lean the mixture out even more at sea level.
The jet can still be drilled out as a guinea pig to larger then the stock size non high altitude jet
I cant find the normal jet for sale just a complete carb for 50 to 80 bucks
 

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Has anybody with an ARIENS wirth the 420 Re-jetted the carb.?
Youyr input is appreciated!
I did when I first got my Simplicity with the B&S 420cc as it was running EPA mandated too lean which increases combustion temps and limits power output. I even took the drastic to some:grin: measure of increasing the idle mixture as I despise listening to a lean stumble from an engine.:smile2:
 

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Discussion Starter #6
Ive been trying to find info out myself
I found a high altitude jet today for the 414cc which could be used to drill out as a guinea pig
tried to find out today if the jets for the 414cc and the 420cc is the same no luck
my jet has a 113 on it have you had yours apart to look?

LCT Engine Part # 41450501 JET-HIGH ALTITUDE
I have not taken mine apart to look.

I am contemplating it.

Trying to learn more.

I have never taken a carburetor apart before.
 

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The jet can still be drilled out as a guinea pig to larger then the stock size non high altitude jet
I cant find the normal jet for sale just a complete carb for 50 to 80 bucks
No guinea pig needed as one can determine how lean an engine is running by manipulating the choke and listening to the exhaust (absence of lean popping) and the smoothing of engine operation.
 

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I can almost assure you that your Briggs and Stratton 420cc engine is also jetted lean and will benefit from upping the jet.

I worked on a seasoned ariens pro28 with the Briggs 420 last year and needed to enlarge the jet to get rid of the full throttle hunting.

I don’t have a size, I used a jet ream and some rule of thumb to enlarge it.

With the engine fully warm, adding some choke is a great way to test mixture. When fully warm, adding choke should cause an audible disturbance and RPM drop. If the engine smooths out, then you need more fuel.
 

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No guinea pig needed as one can determine how lean an engine is running by manipulating the choke and listening to the exhaust (absence of lean popping) and the smoothing of engine operation.
Mine does sound lean also you cant do what you said under a load
the guinea pig is to go as large as you cant without going to far then use the stock jet to go back one size
guinea pig sounds like being prudent to me
 

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Mine does sound lean also you cant do what you said under a load
Accepted service practice is to not adjust under a load

Just like always in the days of past on carburetors that had adjustable main jets and with every manufacturer the screw gets set to a midway point of rich/lean without a load.
 

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Accepted service practice is to not adjust under a load

Just like always in the days of past on carburetors that had adjustable main jets and with every manufacturer the screw gets set to a midway point of rich/lean without a load.
It didnt say it was did I?
load matters
your way does not do under load thats why increasing the jet with a guinea pig works just as they are doing in the honda thread
prudent to use a guinea pig and contine to go up until its to much
ive raisedd my engine rpm 230 rpm
adjustable carbs after set to 1/2 way most times it runs best 1/4 rich from there under load depending on conditions
more??
 

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It didnt say it was did I?
load matters
your way does not do under load thats why increasing the jet with a guinea pig works just as they are doing in the honda thread
prudent to use a guinea pig and contine to go up until its to much
ive raisedd my engine rpm 230 rpm
adjustable carbs after set to 1/2 way most times it runs best 1/4 rich from there under load depending on conditions
more??
Then do what you think you gotta do :icon-shrug:
 

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I think the main jet limits the fuel supply after 75% throttle opening which means the engine is under load and not just running at max speed of 3600 rpm or so. To check mixture you have to run the engine under a significant load for the governor to open the throttle fully for enough time that plugs will get a deposit and then cut the ignition while still under load. In my case with the Gen 3 414 cc LCT engine the plug is dark brown which I think is the power setting at some expense of fuel economy.
 

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With the engine fully warm, adding some choke is a great way to test mixture. When fully warm, adding choke should cause an audible disturbance and RPM drop. If the engine smooths out, then you need more fuel.
This is an elegantly simple approach.

My Tecumseh will sound a bit "off" at full-RPM with no load, if I add 1 click of choke. But more telling may be the fact that it will run weakly if I forget to turn the choke off fully, before starting to blow snow. Even 1 click will make it struggle more under a load. Admittedly, these are at the beginning of a clearing session, with the engine still warming. If I think of it, and we get any more snow, I can try adding a little choke while blowing.

So as much as I'd love to discover that it's running lean, and has more power available, it's probably at least fairly close to being right.
 

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My Tecumseh will sound a bit "off" at full-RPM with no load, if I add 1 click of choke.
A properly adjusted air fuel mix when subjected to some choke will degrade engine operation. A 1/4 turn more on mixture screw past optimum turn would degrade it very badly.

But more telling may be the fact that it will run weakly if I forget to turn the choke off fully, before starting to blow snow. Even 1 click will make it struggle more under a load.
With a properly adjusted air fuel mix any choke will richen the mixture degrading engine operation.

So as much as I'd love to discover that it's running lean, and has more power available, it's probably at least fairly close to being right.
You are right on the money mixture wise but I digress to the small engine race tuners on the forum who have more experience/expertise than B&S and Tecumseh in the way mixture settings are accomplished.:plain:
 

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For you race tuners with the 1/4 turn past optimum theory I would like to see the dyno tests bear this out and if true why would the OEM not do this to claim a hp or gross torque rating higher than published?
 

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Both you guys looking kinda wishy washy without some hard evidence?
 

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Wishy washy is a common forum trait nowadays from those who believe what they wish to believe and does not make it correct because they are the most vocal.:smile_big:
 

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Whats up with you wishy washy guys no u tube videos to back up your claim and are lost? I be the guy to back up his claims with real world experience starting from the late seventies forward when it comes to carburetors.:smile2:

I thought twice about posting this reply but thought what the **** give it to them for all the wrongs incurred from novices.:grin:
 

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Discussion Starter #20
Anybody else re-jetted an Ariens 420cc.

Still contemplating it.

95% of the comments I see posted on the forum about re-jetting seem to be with HONDA's

Just looking for more input with ARIENS / B&S / 420cc
 
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