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I have a 2001 600 EFI Mountain Cat that runs great but really sucks gas. It uses more fuel than my 2003 900 1M with carbs. Any body got any ideas to improve the mileage?
 

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Here are a few setup things to try.

Make sure the track is aligned and that the skis are toed out no more than 1/4". Check the carbides, too. If they are bent, that will add friction and cost you mileage.

Check all the bogey wheels to make sure the bearings are all ok. Some guys will replace the bearing grease with synthetic grease because it has less friction, less friction will give you better mileage.

Make sure the clutches are clean and the offset and deflection is set to spec. Any belt scrubbing can really eat away power, which also kills your fuel mileage.

What kind of chaincase fluid are you using? Synthetic chaincase fluid is less viscous and will cause less resistance to the sprockets and chain, giving you a bit more power.

None of these things will be a magic bullet to get you great fuel milage, but if you do 'em all, you could gain 1-2 mpg at very little cost. It's worth a try.

Check the fuel pressure. As the Cat fuel pump gets older, it seems to develop greater fuel pressure. If the EFI is being overpressurized, it could give you a rich mixture and contribute to lousy gas mileage.

More options
Replace the sliders with the super slippery ones, those give less resistance to the track.
Port the track, there are weight savings in the rubber you remove and less rolling resistance in the track.
Add a lightweight pipe/silencer. Those are a bit spendy, but can give you more power, less weight, and sometimes better mpg. With the pipe/can option, you may have to upgrade the ECU and clutch springs/weights/helix to get the maximum out of the engine.

Lots of things to try, some inexpensive, some more expensive. Let your wallet be your guide ;)
 

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I checked mine on a 97 efi 580 and it was at 40psi and i was getting about 3mpg i've ordered an adjustable fuel pressure regulator from KC Cats. This will replace the fixed pressure regulator on the fuel rack. Just waiting for it to come so i can try it out.
 

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I checked mine on a 97 efi 580 and it was at 40psi and i was getting about 3mpg i've ordered an adjustable fuel pressure regulator from KC Cats. This will replace the fixed pressure regulator on the fuel rack. Just waiting for it to come so i can try it out.

How do I get in contact with KC Cats and how much does a adjustable regulator cost?
 

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I just checked the fuel pressure and it has 60#. No wonder it is getting bad mileage. Arctic Cat wants $218 for a new one. I may try and disect mine and see what makes it tick.
 

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I dug into it a little further and found that the fuel return line from the regulator to the tank was kinked flat so that no fuel was returned to the tank. After I fixed that the fuel pressure is now 40 PSI. That is only a little over the 36 PSI that is should be. I think I will try it this way and see what happens. Thanks for the helps guys!!
 

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40 is still way to high. Mine is at 40 anything over 36.2 will destroy your MPG. You can PM KC Cats and he will confirm the PSI. But i've been dealing with the high pressure and bad MPG since last season. KC's regulator is $150 for my sled it is adjustable so you can fine tune the performance and it comes with a gauge so there is no guessing. RJ and KC have both told me that if i get the pressure closer to 36 it will make better top end and give me the MPG that i should be getting. I've got two other ZR's and they both run around 10mpg
 

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I'm waiting for KC CATS to return my pm so I can buy one of the the adjustable pressure regulators from him. I'll ride it this weekend and see how it does with 40 PSI pressure.
 

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Discussion Starter #14
RJ, Where did you get the 36.2 PSI fuel pressure spec from? I looked at the 2001 Arctic Cat manual and it says the fuel pressure should be 37.9 psi plus or minus 2.2 psi which is 35.7 psi to 40.1 psi. That would make the 40 psi that I have be within tolarance.
 
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