My 2004 650 V2 is stock. It has enough power for the kind of riding and work I do on it so this isn't about boosting power.

My problem is having to rejet whenever I take my CO hunting trips. At a home elevation around 1000 feet, the stock jets work fine. But I have to rejet for CO and the 9500-10,000 ft elevations I hunt at. I don't rejet it myself so I get soaked by the dealer before and after the trip for the rejet service.

I was wondering if increasing the amount of airflow available would have a similar effect as rejetting to a lesser fuel flow? My thought was to switch out the stock airbox and air filter with ones that allow an increased amount of available air into the stock jetted carbs when at high altitudes. Then when I return home, the stock airbox and airfilter is put back in, restricting the airflow back to blend with the stock jets.

Would this be possible? I don't know much about carbs and such and don't want to burn anything up trying.

Thanks
Craig

 

What jet size changes are they making?It should work just leave it jetted for your hunting trips then drill some holes in your air box lid when you ride at home.Find some dummy plugs to cover the holes when you go hunting.Try 1 1 inch hole to start and go from there.

 

Trade it in for 700 fuel injected and won't have to worry about rejetting. [img]i/expressions/face-icon-small-happy.gif[/img]

 

I live at 7,500' and am familar with jetting issues. Increasing air flow via some air box mod would probably work for a few thousand feet altitude change, but not for 9,000' (1-10K). You need to rejet. It's not difficult and with a little practice can be done in half hour or so. Explain to the dealer your problem and ask him to show you how to do it - or have a mechanically inclined friend show you for a free meal.

Another alternative is a Dial-a-jet system. I do not have personal experience with Dial-a-jet, but owner's seem to be pleased with them.
Go here for installation and review: http://www.arcticchat.com/forums/index.php?showforum=52

I believe Dial-a-jet cannot compensate for an altitude difference of 9K, but could be set to run fine up to its limit of some higher altitude, say 5-6K. Assuming that, your bike would run fine in MO and would not need rejetting while you were in CO. It would run a little rich for your CO hunting trips, but not rich enough to cause problems other than higher fuel consumption.

 

I have been taking dirtbikes and ATVs from Indiana to Colorado for over 20 years.
Opening up the airbox will not be near enough adjustment for 10,000 feet.
On my Cat 500 I use a 127.5 jet in Colorado vs the stock jet of 140, which is a pretty big change.
Trading for an EFI ATV would be the best fix but the most costly.
I have seen dial-a-jets work, but they are pretty old technology and may take some trial and error to get working.
Holtzman Variflows are newer tech and been working good on snowmobiles.

Changing the main jets is pretty easy on carbs , the hard part is getting to the float bowl on some models.

 

When I have had mine changed in the past, the dealer went to a 114 from the stock 122 and it ran OK. That doesn't seem like that big of a change. But again I know very little about it.

Two of my hunting buddies don't change theirs at all when we go and don't have any problems. One is a Polaris 2001 425 Expedition and the other a 2003 Yamaha Grizzly. I do not plan to go the do nothing route like they do but it seems a big change isn't required.

Anyone know what guys with 650 Prairies rejet to? I think they start out around 138 to 142 in stock form.

 

Cheapest and easiest cure is to buy a "Dial-a-jet" setup. This system allows you to change your jetting by adjusting a dial on the outside of your carbs.

 

That is probably what I will end up doing. It should get me close enough to where I need to be without burning anything up.

Thanks all.

Craig