Jetting for St. Anthony sand dunes in Idaho

I will be riding the dunes over Memorial day weekend. My bike is set up for Minnesota, where the elevation is about 1,500 feet. I think the St. Anthony dunes are about 5,900 feet. Is this a big enough difference that I need to re-jet.

so what is your jetting and bike set up now?

after all you might be running rich anyway?

and do you really want to pull the carb down for one diddy jet change for one ride?




I first thought Taffy was showing his low altitude roots. But when I plugged in a 4000 foot elevation change, it is just about exactly 5% richer. Again, as Taffy said, if you are already rich, it will be worse in Idaho. If you are jetted pretty well for home, you will just give up a little power, probably won't even notice.

Give Taffy your current jetting and mods. That way you can be sure.


p.s., I have a great little tool/toy, JDs spreadsheet. I plugged in my jetting, went up 4000 feet with one size smaller pilot and one size smaller jet and one position lower needle. The top and bottom were just about right but at 1/4 throttle was a dip that was about 6% too lean. What does this mean. Not much, still give Taffy your jetting.

Mark, Do we buy this tool/toy or is it shareware?

Send "James Dean" a personal message...and he'll coordinate getting it to you. Cost was $20 a while back for me...

rear what town is the st anthony dunes?

i am up north

i would like to go there my self.



The sand dunes are right by St. Anthony Lewichris. Rexburg is also right around there, both are fairly small towns. It is supposed to be lots of fun over there but I have never been myself.

I make an annual trip out to St Anthony every fall. Fun place to ride. It's no Glamis but then again there are no Glamis crowds.

Find out the elevation of Rexburg and that's pretty much the elevation of the dunes (there are some dunes that are maybe 400'-500' tall). It's always a good idea to be a little rich, your bike works real hard in the sand. The dunes are much more fun on a paddle tire (and don't forget to take your front tire down to around 4 psi).

I believe the dunes cover an area about 5 miles by 20 miles. There is camping at the very east end with a little motel and RV hookups or primitive camping on the south center of the dunes at some lake I forgot the name of. I always stay by the lake.

The big dunes are at the west end, some big bowls and big steep climbs. Lots of fun rolling dunes all over the place.

Like all dunes, you need to be careful and St Anthony has some special hazards. At the bottom of many of the rolling dunes are big piles of lava rocks. Certain times of the day the contrast gets very low and it's hard to see little drop-offs and step-ups. No real big slipfaces but many little ones that fall into those rock piles. It tends to be windy there so be prepared for that.

There is lots of vegetation among the dunes and some dunes are isolated by vegetation. People have blazed trails but most of these are clearly marked as closed. PLEASE respect these signs. There has been talk of closure (the Dunes are also home to the largest wintering range of Elk in Idaho).

If you have any other Q's send me a PM and I'll try to help you out. Remember to be safe. The last 3 times I've been there over a 3-day fall weekend, someone has been life-flighted out. I rode a kids YZ-250 out of the dunes that flew over the top of a dune blindly wide-open in 3rd gear and landed on the uphil side of the next dune. He broke his back and looked very uncomfortable as we loaded him into the helicopter.

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