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Discussion Starter #1
I just pick up a 2002 800 ZR with a Black Magic Super single, EGT gauges. a Power Breather Air box and a D&D clutch kit...the sled was ran last year with the pipe, clutch kit and air box and performed well...(I was told from the seller)..since then I have added the silencer a MBRP race can. I took the sled out and it idles at 500 degrees at about 1500 rpm.... and runs at 1100+ - degrees at 5000-6000 rpm..at a steady speed..about 40-50 mph. The temp outside was 0 degrees and I live in Maine...about 400' above sea level. I was worried about running it harder...it seems to increase in EGT as I increased the throttle. Should I increase the main jets...(all the carb turning is still stock)..or change needles position...seems to increase in temp just as the mains take over (about 1/2 thottle)...I forgot to mention that the air box intakes were closed up..I want to keep the silencer on..sounds great in the woods!!....any info would be helpful...sled runs great...just concerned about the temps....is this normal?? I just bought the sled yesterday...$4000.00...looks new...1300 miles on it. I live in Millinocket Maine...the paper mills just closed there doors last week files chapter 11... they owe 100 million dollars!!!...I said 100 million!!....1100 people out the door...sleds are selling real cheap here...the paper mill took all the 401k accounts, insurance, and pensions...wiped everything out..sucks for the people here. A Canadian group bought the mill last year called the mill...Bowater....nice northern friends!!
 

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Here's a comparison for you. My 02zr8 is stock except for v force 2 reeds and shaved heads. The mains are stock 430's. At idle the EGT's are under 400 degrees. 1/4 to 1/2 throttle 1050's to 1130. Full throttle back down to 900's to about 1000. These numbers were from riding today with air temperature in the low teens to single digits. I feel this set up is rich and could safely drop the mains a size or two. I haven't seen a temp. over 1150 this year. What do your plugs look like as well as piston wash?
 

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I can't tell you what the 800 is supposed to run exactly for EGT, but it should be around 1100-1200. Because there are multiple fuel mixture circuits in a carburetor fuel system, you could be lean (hot) in one area of the throttle, and rich (cold) in another. As long as the EGT does not exceed the max temperature, everything is ok. If you increase the mains you won't affect the part throttle fuel mixture very much and won't see much of a change. Raising the needle will have more of an effect at 1/2 throttle, but you still need to see what happens at WOT. If anyone out there has a newer Performance Manual they could tell you exactly what normal and preignition temps are for that engine. Also confirm that the EGT sensors are positioned correctly. Any change from AC specs will give you false readings (too close=hot; too far=cold). The sensor tip needs to be centered in the pipe too.
 

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The ZR800 timing curve has it's hottest spot at between 6000 and 6500 rpm. This is where you must use caution when jetting, especially if trail riding where you'll cycle through this rpm range frequently. It's not as critical when dragging or doing radar runs as you'll streak through that range quickly and not frequently. Timing keys can also aggrevate this condition as they'll make that range even hotter. Jetting around this may require both needle clip adjustments as well as the usual main jet changes.
Good Luck!
 

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Discussion Starter #5
Thanks all the info...can someone tell me what area (temp) I should start to worry about before melt down...1200 degrees...1300 degrees?? I have contacted several sled heads in town here and have indicated that everthing look good...plugs were light brown.. I'm just puzzeled why this didn't happen last year...I feel that it might be the silencer OR the gauges...I'm about 3" away from the outer wall of the clyinder...I'm going to go to 440 mains tomorrow. All of your responses stated that I should run it wide open...will do that also..thanks!!
 

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You have to read the plug colour and piston wash in order to know what the EGT reading means. The right EGT reading is unique to each sled because no two installations are indenticle. First find your baseline jetting starting with your main jet. Once you have the plug colour and piston wash where it should be, then look at your EGT readings and that will be your magic number, and yours alone. Check your plugs and piston wash at half throttle to set your needle position and fine tune from there. You should only need to change your main jets thereafter according to air temperature and density. At this point your EGT readings will tell you when you are about to burn down, or if you can lean her out. Otherwise get a Tempa-flow and throw the EGT's away.
 

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Discussion Starter #7
Spent most of the weekend running sled and trying to get the temp down on the EGT...changed mains, went to 440's no luck...cleaned stock mains, pilots and started jets...no luck...running way TOO HOT it's hard to check any wot runs or true piston wash temp increases as RPM increases....could my fuel mixture screws be dirty??? this is the only thing I haven't cleaned or checked in the carb system...would anyone know how many turns you back off from the seated position...these might of been turned by accident during my last shop visit...I will post a new forum just for these screws..
 

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you stated in your earler post that you didnt have this kind of temps last year,then you added an can to your sled, then the temp came along, i would try puting the stock can back on and see if the high temps go away??. another thing you can richen up the bottom end is to buy an richer slide for your carbs.
sno_pro_500
 

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What temperature is too hot in your opinion? Trying to get your temps down will give you a rich condition, resulting in high fuel consumption and low power. I don't agree with 94ZR580. While all machines are different, if you place the sensor in the area the Team Arctic Performance Manual states, the reading for your sled should be similar to what is listed for your model in the book. EGT is not an exact temp and there are ranges for each model, but the numbers are based on maximum temps. Unless you are running a different cooling system inside the engine, or pistons made of different metal (or coated), then the EGT is used to warn you of a possible meltdown or piston scuffing from a lean mixture. I would say use what the Performance Manual states as a 'normal' reading for your max temp. I find it hard to believe that Cat would publish a manual with EGT numbers in it if they weren't reliable readings to use, and that your cylinder, head and piston are so much different than other 2002 ZR800's that there would be engine damage at a different temperature than what they found. Your cylinders and pistons were cast in the same molds as everyone else's using the same materials!!!! Isn't there someone out there with a 2002 Performance Manual that could give him Cat's recommended sensor position and temp for his sled?????????
 

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Get your hands on a 2001 AC Performance Manual.
Correct probe location and maximum EGT's are listed there for each model.
Unfortunitely, AC did not publish a 2002 Perf. Manual covering the ZR's. Only the racers received a Sno-Pro specific publication in 2002.
 

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Thanks for the info MUSKOKA800. I didn't realize there wasn't a manual available for the 2002 models. The engines are the same for 01 and 02, so that would work.
 

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Discussion Starter #12
It's me again...NEVER had this problem last year....sled temps ran within Arctic Cat's range last year...1100-1200 at WOT ...should idle at 325-350...always kept an eye on the EGT temp gauges. I did put the stock muffler on yesterday and it stills runs hot...idles at 600-800....increases as you increase thottle.Could be the fuel mixture screw?????????? it's the only thing that I have not looked at...if these are dirty or clogged could this cause thus hot problem????
The cylinders and pistons still looks ok inside....thank God for those gauges!. One more thing how many turns should these screws be turned out from the seated position?......hope to get this fixed...had to ride a Yamy last weekend :wacko:
 

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bowl vents clear? tank vent clear? fuel pump putting out enough? these things could cause leaness. carb boots cracked? could cause leaness, also.
I saw on another post that a fellow had his pickup hose swell almost shut in the tank on an 02- this could cause leaness.
 

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Discussion Starter #14
Just got back from dealer with the sled.....took carbs apart check them...seemed a OK...ran it on a railroad bed at WOT for a 1/4 +...plugs somewhat light brown, piston wash looked OK...gauges read 1500 degrees!!! at WOT... mentioned that gauges have to be off...I'm running Digatron DT-52SNL gauges...dealer said to run it and to send gauges out for re-cal....still worried about readings...could gauges be off...as mentioned before this all started at my first ride 3 weeks ago. I mentioned to fuel pump to him but indicated that the sled would run rough...it doesn't. Any way to back flush the fuel pump...any more info would be helfful...
 

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Maybe the probes are shot? The guage is solid state electronics isn't it? The probes can get damaged or burned up, so maybe they are the problem. One or the other, or both. If the plugs and wash are good then that is great and that is what counts. You might want to consider a Tempa-flow so your jetting will stay on track all the time, I just realy like mine. It's good news that your jetting is OK, so now you can ride and have fun with no worries, unless the air temperature drops from what it was when you did your test.
 
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