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Discussion Starter · #1 ·
Took my 04 F7 to Dynotech on Monday with hopes of figuring out why the sled hits a wall at 90 MPH (top speed only 98-99mph) and just doesn't feel as strong as I think it should. Obviously, the motor ain't the problem! Jim said "It's a strong one - Leave it alone for everyday trail riding on 87 octane" and, " I could get it to 150 easy if you were willing to run 93 octane". Jim's confident that my HP is a result of the 05 program in my 04 ECU.

So, what next? Clutching? - It seems pretty close to perfect with my ODS kit. It might need some tweaking but I doubt I'm going to gain very much by messing with it. Gearing? Maybe. Since the 04 SPs are geared lower than the standards with the 1" track (and all the standards seem to run well), the 23/40 gearing MAY be part of the problem. I've got the 24/39 std. gearing to try but I'm concerned that the low and mid range acceleration in the trails will suffer. Anything else? The track is aligned and I run it as loose as possible - everything seems to spin/rotate freely. Is the combination of the 1 3/8" track and the 031 belt a problem? Maybe? I even have a 1" track to try but changing tracks ain't my idea of a good time and besides, I like the bigger track in the trails.

Anything else you guys can think of? I'm happy to know that the motor is strong (2500 miles on it) but now I'm really wondering what to do next. I'm not a lake racer but do like to open it up on the wide, flat trails in Maine and I've had many times where I'm running flat out and just can't stand the fact that it seems to be working hard to reach 90mph. I've also have had a bone stock 600rev stay side by side with me on a lake. That was embarassing!

Here's the dyno sheet...
 

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Well...correct me if I am wrong but I think the "taller" gearing of a Sno Pro is better for your sled (top end problem). I would say your problem HAS to be in the clutching...but unsure where to even begin to speculate a problem. :dunno:
 

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I live in ct too how long was drive? My suggestion would be to go for the gearing Maybe your sled was intended for high elevation for some reason? I would change gearing its easy and takes about 30 min. try that i bet you will be happy I did not find the need for the 1.375 where i ride. I had the sno pro track on mine and changed it to the hacksaw 1 inch this year have not ridden it yet. I have an 05 and saw 109-112 on gps with dd and 1.375 track.. i would say just do the gears if you dont like it change it back im sure you will like the change it made a big diff in my wifes saber. Oh yeh what are your rpms at full speed?
 

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Discussion Starter · #4 ·
Originally posted by sledsearcher@Oct 19 2005, 06:10 PM
Well...correct me if I am wrong but I think the "taller" gearing of a Sno Pro is  better for your sled (top end problem).  I would say your problem HAS to be in the clutching...but unsure where to even begin to speculate a problem. :dunno:
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The SPs are geared "lower" or "shorter" than the standards to accomodate the extra bite of the larger track. Not "taller".
 

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Discussion Starter · #5 ·
DR F7 - It took me about 6+ hours towing two sleds and taking it easy (dropped the other one off at the dealer in Utica on the way back). Lucky for me, I had to go to Buffalo anyway for work so it wasn't a special trip.
 

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How can i get the 05 program for my 03???
 

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Discussion Starter · #7 ·
Originally posted by firegrizz7@Oct 19 2005, 06:18 PM
How can i get the 05 program for my 03???
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Go through your dealer. They can send it in to AC.

You can probably get the same results just by leaning the top end down with a fuel restrictor like the PAC.
 

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I guess I am confused...maybe I misspoke about "taller" but if you look at the chart in this thread it shows that given the same conditions...i.e. drivers, track, motor, etc. the stock gearing 23/40 should pull more MPH then the std gearing (22/39).

http://www.hardcoresledder.com/forums/inde...l=gearing+chart

:dunno:
 

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Discussion Starter · #9 ·
Originally posted by sledsearcher@Oct 19 2005, 06:27 PM
I guess I am confused...maybe I misspoke about "taller" but if you look at the chart in this thread it shows that given the same conditions...i.e. drivers, track, motor, etc. the stock gearing 23/40 should pull more MPH then the std gearing (22/39).

http://www.hardcoresledder.com/forums/inde...l=gearing+chart

:dunno:
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I'm sorry. I posted the wrong gearing info. I have the 23/40 now and the std. has the 24/39. I have a set of the 24/39. Don't know where my other numbers came from. :doh:
 

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Couple of things to look at on your machine. One is to see if your brake is dragging ever so slightly? as your speeds increase the heat increases on the brakes swelling everything and slowing it more...its a progressive effect. Another thing to check is to see if the track is hitting your tunnel at high speeds. You may have your track too loose. at high speeds your track trys to "balloon out" and that may be causing a problem. Me personally, i wouldstart at one end and work my way back the sled checking everything....From ski alignment, clutch alignment with C to C, Even go as far as gear alignment. All of these things can cause a parasitic effect on top speeds.
 

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I had my 03 dynoed and had real good numbers but when I was running my sled on the grass I just didnt have anything on the top end and my gearing was right on I did a compression check and it was good but when I did a leakdown test it wasnt good I rebuild the sled and it took care of all my problems. I would start with the cheapest items then work towards the costly items Compression check and leakdown tests are cheap.
 

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I am having the same problem with my 2004 f7efi, I wont break 100mph also a dog on the bottom. How do u do a leakdown test. I think it's my clutching because it revs to 8200 + and never drops.
 

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Bull, I pulled 118 with my 1.375, and pulled 100 last year witha 1.5 track, and that was turning at wayyyyy too many RPMs. 8400 to be exact...can you say over rev, boys and girls? Good i knew you could say it......lol
 

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It most likely is the track. My buddy put a D&D kit in his f-7 ran95 hit a wall called them they said send us back your secondary spring, they gave him a new one & now he hits 112 plus, & he weighs 215lbs. It is a standard, with 1' track. sounds like your not getting full shift out.
 

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If you have a friend that has a 2003 F7, try his clutches on your sled and see what you get. I have a friend with a 2004 standard that did the same thing, we switched both clutches and his sled was faster than mine. That was with my clutching on his sled! Can't hurt anything to try it once.
 

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swapping parts with a proven sled aint a bad idea...

one other thing is your limiter straps... some people tighten them up way too much...

even if you decide not to mess with the gearing i think it would be a good idea to at least pull the chaincase cover and inspect... :dunno:
 

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Discussion Starter · #20 ·
Guys,

Thanks for all the comments and suggestions.

For those that continue to say "It's the track" - I can see the track costing me as much as 5 MPH on the very top end but not 15 or more. I have heard about plenty of 03s, some 04's and some 05's with the 1 3/8" track easily hitting speeds around 110 on radar and GPS.

As far as the leakdown and compression tests go, I have not yet been able to get either of these done reliably. With almost 145HP, I doubt there's much I can do to improve on the perfomance of the engine.

So, I'm down to clutching, gearing or some other drivetrain related issue. It just sucks that the season is so short and the nearest decent place for me to ride and test is about 2 1/2 hours away! :banghead: :banghead:
 
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