Ask the Experts: Tuning for Elevation

Do I need to tune for riding at different elevations?
Polaris Indy Lite, Wisconsin Northwoods snowmobile trail
Paul and his wife, Marla, shot us this trailside-selfie from the Wisconsin Northwoods.
Q. I purchased and restored a 1992 Polaris Indy Lite GT and a 1993 Polaris Indy Lite. My wife and I now reside in El Paso, Texas, and travel to Eagle River each year to ride and watch the Derby races. However, our closest riding destination is northern New Mexico and Colorado where the trails tend to be at very high elevations. I had to adjust the carb jetting to even get the sleds to run at the higher elevations.
We are wanting to purchase newer machines, but want to know if the newer, fuel-injected sleds managed by an ECM still need manual adjustment when you go between varying elevations? -Paul V. from El Paso, Texas

A. The short answer to your question is that the fuel injected sleds of today will automatically adjust the fuel mixture for proper performance at various elevations. Seeing as you’re mostly out for leisurely trail rides, we can’t think of any reason for any sort of tuning adjustments to a sled powered by a fuel injected engine. While the performance aspect may see a slight decrease at the very top end, the difference is minimal, and well within what would be considered an acceptable range for your riding application. -Experts
Arctic Cat ZR 200
snow bike
What is the hold-up?
Q. I keep hearing all things about the SSCA regarding snowmobiles. I heard it with sleds from China that were smaller when I was at a snowmobile show a while back and now I am hearing it again. I am wondering what this is and why it is important to snowmobiling. From what I gather, it is an exclusive club or something because I can’t find any information on it, but supposedly I should know. Thanks! – Clutchit3

A. There is a pretty rigorous set of standards that snowmobile manufacturers must adhere to as far as safety is concerned. The Snowmobile Safety and Certification Committee has been around since 1974 and they are the sponsor of the certification and auditing program which uses their independent labs to test snowmobiles to make sure they are up to their snuff, safety-wise. Sleds then get the SSCC badge of approval (certification mark). This process encompasses much of what “constitutes a snowmobile” on the trails today. It is a long and arduous process, but in the end these are the regulations and processes for snowmobiles that keep us, the riders, safe. One reason you see vehicles like the new Snoscoot and ZR 200 as well as the SVX snowbike vehicle (or certain snowbikes getting ruled as snowmobiles at all) taking so long to come to market is that these vehicles must pass the SSCC tests. It is not easy to pass all the little things that the SSCC requires when manufacturing a snowmobile but there is also a lot of paperwork. Snowmobile systems monitored include things like brakes, electrical systems, lighting, shields, guards, exhaust, controls, and more. - Experts
2013 Ski-Doo MXZ 600
On the Brakes
Q. I own a 2013 Ski-Doo MXZ 600 H.O. E-TEC. When I run slow, it feels like I am running with the brake on. The tachometer will surge. The plugs are black, but will clear up after about half throttle. We checked the jackshaft and found no binding on the track. We also set the chain tension, and checked the fuel pressure. All were OK. We’ve done a leak-down check, and found compression at 120. We did install Boyesen Reeds. We would appreciate your input. – P. Rapp, Coudersport, PA

A. Fuel pressure typically will not be an issue, as the E-TEC injector changes that when injecting. The tachometer surging issues are typically related to incorrect fuel-to-air ratio at slow speeds. There are a lot of possible scenarios that would lead to this. Be sure the injectors are flowing correctly. Check that there aren’t any intake air leaks, or just remove the reeds and recheck that everything is working properly. – Jason Houle, Straightline Performance
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