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Discussion Starter #1
Well I have seen some posts on here with unbelieveable times and speeds for snowmobiles. It makes me feel like I am out of tune with what people are achieving from thier snowmobiles. I am interested mostly in trailable machines, improved classes, you know something like we could build, not race sleds. So my question is... what is the fastest improved stock run you have personally witnessed and what sled was it.
 

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I don't know about the "official" drag runs, but I saw a guy on skiis getting pulled by a thundercat cross the light at 92MPH!! And that was with a radar gun.
 

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Go that speed, the last thing I would want to be on is skis...
 

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There are radar runs in NorthBay every second weekend, the guy who runs them but I can't remember the web site, D&D something or other. I lost all my old favorites when I loaded XP on my comp. Maybe canadiantim2 will know.
 

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well the fastest improved stock machine i witnessed was the xlt sp i was on doin 100 in 1000 ft. i thoguht that was good for the ol sled.
 

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www.doubledracing.ca/
sleddaver this is the site
 

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in trail form last year i got 108.4 this year i hope to get to the 114 mark in stock class. speed running is a lot different set up than draggs. on your sled get the engagement down to 3000 with a ton on wiehgt and very little secondary spring pressure and helix. more wieght with less engagement with less helix and less secondary spring means more speed but longer ets. click the springs to low screw down the front springs and crank up the limiter straps, have only on good carbide. thats just a start.
i wouldnt get more than 192 pics. i am going to try dropping to 168than even144 remember it is a speed run not a dragg. if you spin with a 192 than you need to lower your rpm or use less helix. you want just enough ski pressure to steer for that day. you have the clickers so just add more wieght like a gram or two or three to the two screws leave the heal alone. kinda, just so your rs dont jump at the line than come down to climb back up. dont run a secondary spring any higher than a polaris blue in the first or second hole. if you have to use that much spring you have to much helix. jet down to 360 mains with the needle down one line. check your wash for jetting for that day. get some pjs fuel additive. you can save your engine on a lean burn with it.
 

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Discussion Starter #8
Thanks for all that Madcow. How far are you running. I was actually fishing for distances and speeds more than how it was achieved. I have a fast Ultra and I have used some of the above tips over the last 4 years. I didnt radar the XCR yet but an aquaintence is getting alot higher times on his than 108 mph. 123.4 to be exact. His is stock with none of the above done to it. It dosent feel like mine will go that fast. Have to wait and see.
 

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You guys must be running 2000', if something stock runs 123 mph. Our stock ZRT800 runs average of 114-115 in 1000'. Improved stock 800s run 122-127 mph in 1000' on shaved ice.
 

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im only going 800 and 1000 feet.
 

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Discussion Starter #11
Ok that makes sense. Madcow have you done a 1500 or 2000 and what speed did you achieve. Also have you got more info on the fuel additive you mentioned. Will it actually compensate for a lean jetting situation
 

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no i have not ever done longer. the additive is like PJ's or something. i will be getting a couple more casess in a couple weeks. if you have good fuel and run this stuff it can help some. for racing i use it heavy. the thoery is that it will help you go into a cold burn you will stop gaining speed and start to slow. but in 1000 ft you would need to get real cold and almost plug a jet to wreck that xcr engine, thats what i am hearing. i ran 380 last winter and by the amount of wash i could have almost trail rode with them. i think i will get down to some 340 or close to that. i hear grass draggers running in the mid twos.
i you mix a mild ratio of nitro methane and jet a little richer than straight gas you will most deffinatly get a cold burn before lean burn. i met some yami guys doing this and they never had a piston problem but had ran into a lot of cold burns.

if you are running 1500 2000 i would stay in the high 300 to low 400 for jetting. check your wash take notes of temp and work down. in a 2000 foot run i think jetting would be less critical because you are building plenty of pipe heat and cylinder temp. in the 800-1000 feet i run it on the stand for a bit at full throttle just to get some pipe heat and clean the motor of any fuel.
 

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Don't forget gearing, to go fast in 2000' you need gear. Also running nitro is against the rules in stock........ DD and alot of speed runs will be teching this year.
 

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teching. at the local ones it seems like a free for all. only teching is a compression check. they do the runs for fund raisers. there is no one qualified to tech at most of the runs.
 

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yes. but at like rush city or pine city if you set your heads to isr legal squish, they give you a compresion test and say your to high, they dont have the tools to measure squish.
what did they tech on your zrt last year at rush city to move you up to improved stock.
 

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We never moved to 600 improved we run a stocker and
an improved. The stocker is a 98 and the improved is a 97. The 97 is a 3 time NSSR world record holder. All of the sleds we run have been teched at one time or another and have always passed.
 

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Easy to measure squish. Get a roll of plumbing solder, bend and insert a piece into your cyl so that it touches the cly wall. Then slowly bring the piston to the top , remove the solder and then mic it. Give it a try.
 

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yeah i dk about all this non sense on the "top speed" forum the whole 125 and 115 on there "stock" xc 600, i've been donw the radar trail a couple times...and thats unheard of, and them saying that speedos are acurrate...no they are, manufatures set them at 10% above actually speed so the faster you go the more mph your off by and the fastest 600 is 110 is what i have ever seen..125...the rx1 hardly does that! the ran 127 on radar last week, so either he is lieing or has a exteremly modded 600
 

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i was told that they moved your zrt 800 up to improved stock because the compresion was to high, on the feb 2 race. i am not saying this to be funny, it was what i was told. i want to set the xcr heads to isr specs but i dont want to get tech out of running becuase they dont tech right.
 
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