Top end rpm

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03escape800

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Jan 22, 2008

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• Jan 3, 2010

• #1

03 Vertical escape 800 159, twin pipes, airbox, ATTAC compensator, V Force reeds. Having problems getting top rpm. Seems to peak out around 8100, and then as I back off the throttle it seems to pull harder. Tried different jetting, clutching, exhaust springs-nothing seems to make a difference.
I read somewhere on a Mikuni write up that if the engine seems to pull harder as you back off that the jetting needs to go larger? Running out of ideas-help!
Had 440 in main and dropped to 420s with no change.

 

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devilrmk

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Sep 14, 2006

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On the toilet

• Jan 3, 2010

• #2

What elevation?

Not sure with ATTAC but I was running 420's at 3000ft with 02 needles, so with 03 needles you should be in the 370 range.

Twins really won't pull the R's without the jetting pretty close.

 

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03escape800

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Jan 22, 2008

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• Jan 3, 2010

• #3

Run around the 2500 ft range, but don't rejet if run in the mountains which can change from 5000-8000 ft. ATTAK system seems to keep the plugs looking the same. Richer brown color with touch of gray on electrodes. With the twin pipes, SLP says I should be running 480 mains, but I am down to 420s right now and leary of going much smaller.

 

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locknload

Active member

Dec 5, 2007

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• Jan 3, 2010

• #4

Unhook the attac and try it, I was having the same problem-rpms would actually surge a bit after a long pull, Unhooked the attac and jetted for altitude and problem fixed- even had to throw more weight in primary (over revving). The attac works great on a closer to stock setup but after certain mods it struggles a bit. Hope this helps. Also my spark plugs always had great color thats why it took me a year to find the problem.

 

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03escape800

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Jan 22, 2008

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• Jan 3, 2010

• #5

Tried unhooking attac but with the but did not seem to make a difference and have no idea where to start for jetting but SLP does say to use around 360 at 6-8000 ft.
What sled are you running with what extras?

 

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locknload

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Dec 5, 2007

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• Jan 3, 2010

• #6

I have an 03 700 vertical edge with a 153 a20,team secondary, slp single with thing can, v-force 3, slp high flow air box, flow rites. I run 340 mains at 8-9500 ft. Have you checked your clutches, worn-out, bad springs etc..

 

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03escape800

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Jan 22, 2008

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• Jan 3, 2010

• #7

Tried other clutch set ups. Took set of clutches off identical sled that worked wicked in the mountains and made no difference on mine. Mikuni states that if after holding wide open for period of time and then you back off slightly on throttle, if power increases, then larger jets needed. This seems to be opposite of what the jetting charts and everyone else seems to be telling me on how to jet.

 

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theultrarider

Well-known member

Nov 26, 2007

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Soldotna Alaska

• Jan 4, 2010

• #8

I've got an 03 escape with a ubr ported motor slp heads running slp race twins. Also have an 03 rmk with consumer twins. And an 04 prox2 700 with dynoport race twins. I live in Alaska and ride from sea level literally up to about 6000' regularly. Most rding is 2-4000" I am running 380 mains in my escape and running fat. I should be around 360's. I am running 370's in the boys prox and the wifes 800 with the consumer twins is right in the same ballpark. I forget on hers cuz it runs so good I havent touched it in a couple of years. Bottom line is jet down. Slp's chart says I should be running 520's or something. They won't pull out of the garage jetted like that.

I also agree with the guy who said to disconnect your ataac until you get your jetting right. Once you get your jetting where it needs to be, then hook it up and jet it for the coldest, and lowest elevation that you will see. Proper installation is everything on the ataac's also. They do work well on the mod sleds, but the setup has to be perfect.

 

Last edited: Jan 4, 2010

westsledin

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Nov 23, 2008

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• Jan 5, 2010

• #9

I have an '03 800, 151 and twin PSI pipes. I am running 380/390 for jets upto 6k.

 

whoisthatguy

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Dec 27, 2007

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• Jan 5, 2010

• #10

Once you have an atacc installed, what anyone else uses for jetting is irrelevant. Your jetting is highly dependant on what base elevation you chose to reset the Atacc by pulling and reinstalling the blue tube. It is unlikely that anyone else chose the same elevation as you. Atacc's also only last 2 years. Then they stop working properly, if you can believe what the salesman tells you. Polaris sleds come with stock gearing as if every one of them will be riding through the snowpacked cornfields of Minnesota. They are geared too high for mountain riding. If you buy a bottom gear with one more tooth than stock, it can make a noticeable difference, because you would be gearing it down. Then you can get higher RPMs when hill climbing.

 

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carguy

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Jan 8, 2005

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• Jan 5, 2010

• #11

whoisthatguy said:

Atacc's also only last 2 years.

Click to expand...

What???
What do you base that statement on?

My brother has had one in his Polaris since 2001 and his machine pulls as strong as ever. I've always been amazed with the performance of his RMK compared to my 2004, which also has an Atacc on it. Now Holtzman did tell him to send it back to them after the season to get it checked/rebuilt/recalibrated because of its age. But I have never heard that Atacc's last only 2 years. My Bro's machine is proof of it working spot on.

Perhaps the problem with the top end rpm is related to clutching if plugs & piston wash check out. Tachs on the machines are also inaccurate and can be calibrated...another area suspect. Is the 8100rpm you see accurate?