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Pilot jet adjustments

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Pilot jet adjustments

Postby ZR500PA » December 12th, 2001, 11:01 am

Has any one found that they had to drop their pilot jets on their arctic cat. I was told to do this on my 500. I don't know if this is a good Idea or not,could use some help.
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Pilot jet adjustments

Postby straycat » December 13th, 2001, 12:26 am

The pilot jet controls your low speed and idle. if at idle you notice that the plugs are building up alot of black oily residue they are to big. If not they are right. if they are, then you have to make adj.
I would first make shure that the air screw for the pilot is out 1 1/2 turns. and make shure your idle is correct.
Till the speed overcomes the fear of death!

Long live the cat!
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Pilot jet adjustments

Postby ZR500PA » December 13th, 2001, 1:59 am

I was fouling plugs on warm ups, So a guy on here told me to drop the main two sizes, the needle one notch, and lower the pilot jet one size. Last year i did all but the pilot, this year I did the rest,it seems to run great,but at idle it seems to have a lean pop in the exhaust, I think Im going to Go back up the size.The plugs always look rich, I only got to ride around the fields so far this year and never a chance to give the plugs a good run.
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Pilot jet adjustments

Postby straycat » December 13th, 2001, 3:07 am

If you are poping back threw the carbs you are to lean. the piolt jet only regulates fuel flow at low speed and idle. if you open up the trottle to 1/4 the main fuel supply then takes over and the piolt no longer has an effect.

If I said it once I'll say it again. there is a book aut about carb tunning. Olav Aaen's Carb Tunning Hand Book. this book will tell you how to tune your carbs to get the best performance out of them, And what to look for. I swear by it.
Till the speed overcomes the fear of death!

Long live the cat!
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Pilot jet adjustments

Postby michahicks » December 13th, 2001, 4:07 am

OK, my 2 cents on pilot jets. They need to be changed if you cannot adjust the mixture to your satisfaction with the idle air screws. If the screws are out beyond 2 turns or so, and the mixture is still too rich, the current jets are too big. If you are running the mixture screws in beyond about 1/2 turn the jets are too small. You should be able to keep the screws somewhere between 1/2 and 2, maybe 2 1/2 turns at the most.

Popping back through carbs is running lean. This would be normal only if it only happens when cold.
Good luck
Al
1997 38' HR Endeavor, 275 Cat, Freightliner
2003 CR-V Toad, Blue Ox, Ready Brake
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Pilot jet adjustments

Postby Snotcicles » December 13th, 2001, 4:19 am

Hey, what year is your ZR5? I have an '01, and it seems a little rich in the off idle - low mid range area. I was thinking about dropping the needles one notch to lean it out some. Top end seems o.k. especially on 20 degree and colder days. I was reading in a magazine recently that the manufacturers have been shipping models a little fat on jetting to reduce warranty claims for seizures. I guess to them it's better to sell more plugs and gas then to have the jetting be spot on for max performance. I would rather replace a plug than a piston too, but I also like a crisp throttle response. Hopefully I'll get some snow around here soon so I can do a little tuning.
A picture is worth a thousand words.
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Pilot jet adjustments

Postby ZR500PA » December 13th, 2001, 5:57 am

My 500 is a 01 too. I have dropped to 310's with the old pilot in. and I run at 1500 feet most of the time and I beleave it is still little rich. I have 96 cougar that I dropped three sizes on and there is no danger of burn down to below -20 now on the 500 I would not push it to hard down that low. Drop the needle one slot, an old arctic cat dealer for thirty five years told me that this equeals a half size in the jets. saves a ton on gas, I have gotten 17 mpg with this setting.
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Pilot jet adjustments

Postby Snotcicles » December 14th, 2001, 3:05 am

17!!! thats huge... my best was 14 taking it real easy. I'm going out to the garage right now to drop the needles one notch. I want to wait for some snow and colder temps before any other carb mods. Where I ride it's probably 1000-1500 asl so I might end up dropping the mains a size or two too, I really notice it when its about 30 degrees out it kinda burbbles and is sluggish. But at 20 and colder, it runs great.
A picture is worth a thousand words.
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Pilot jet adjustments

Postby ZR500PA » December 14th, 2001, 6:50 am

Just about every cat that is delivered in my area is jetted for -40 If you go by the chart under the hood you will still have some margin of safety, Put 310's in and drop the needle one notch and on days when it's 0 just don't hold it wide open for a mile. I had no problems, only when I just started to warm it up did I foul plugs. Not all the time just now and then on warm days.
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Pilot jet adjustments

Postby yellow snow » December 14th, 2001, 7:41 am

The easy and safest way around all of this is to jet for -40 and buy yourself a tempa-flow and it will run right till you hit +40. They are about 120.00-130.00 and worth every penny. I got mine from jumpstartracing.com and they will answer all your questions and etc. Good luck.
Yellow snow

[red]DON'T[red] EAT[red] THE[red] YELLOW[red] SNOW[red]
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