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Fuel injection VS. Sea level??


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Ok just got back from a trip at hatfield mccoy and on the trails ran over some kind of metal and shredded the sidewall to my brand new front tire>>> anyway where this is going, i go to the tire shop and start bsn with the owner of the shop and he says... no way he would ever buy a fuel injected bike!! He says that different elevations really mess with the bike like blowing things up!?! now im kinda new to the riding/fixing scene but didnt sound like any truth? Anyone have anything they have heard of or had happen to them especially the 450X cause im about to buy one but he scared the bejesus out of me and now im having second thoughts. Please help!!

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My Rancher is an 07 with fuel injection, so it has seen a lot of hours. This machine has been ridden everywhere from BELOW sea level to 12,000 feet, and the FI is absolutely trouble free and performs fabulously! Our typical ride in the Sierra, goes from 4,000' in the valley to over 10,000'....all in one day's ride.

I will most likely never purchase another carburated dinosaur ever again!

Edited by reconranger
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You haven't heard of any late model cars with EFI blowing up when driven at varying elevations have you? EFI compensates for altitude variations for you to keep the fuel mixture in a predetermined range and your vehicle/ATV running efficiently.

And besides, realistically how much real altitude variation do you actually have to deal with??? I know back east you think of a couple thousand feet of altitude change as a "mountain" (for the record, I grew up in WVa), but that is just a "hill" out here in the west.....

Edited by reconranger
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Reconranger very funny cause never road out west and west virginia does feel like real mountains!! Ha Ha! Guess im missin out?

You easterners have some great property out there, but recon is right it's a little harder on internal combustion engines out here.

Pulled this from: http://www.usacracing.com/ppihc/about/overview

The race is run on a 12.42 mile course with 156 turns that begins at 9,390 feet and finishes at the 14,110 foot summit of America’s Mountain; Pikes Peak! As the drivers climb toward the summit, the thin air slows reflexes and saps muscle strength. The thin air also robs engines of 30% of their power at the summit. Competitors and vehicles must be in top shape simply to finish...let alone win!
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On a finely tuned high compression 2 stroke. I would recheck the jetting if there was more than a 25 degree difference or anything more than about 800' elevation change. I run that quad competitively against much larger CC banshees. I have seized a motor for running too lean after a cold front blows in, just due to the atmospheric pressure change. I try not to run quite on that ragged edge anymore. 4 strokes are a little less finicky, but for top performance (competition) I would say you would start to be a little rich at about 1000' difference.

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At what elevation/humidity change does jetting realistically need tweaked?

for the record...

4700 pikes peak elevation change

1700 HMT rockhouse elevation change

We ride our carburated quads everywhere the fuel injected ones go, and that means a change of at least 6,000'+ vertical on a single day's ride! So here is the secret....

Jetted for your lowest base altitude, install a couple Thunder TPI valves in the airbox lid. As you ascend in altitude, open them up for more air. As you descend, close them down again, for less air. Above 10,000', I just pull the lid off altogether. This is a rejet in a very real sense, only you are adjusting the amount of air rather than the amout of fuel! Why fool around with jets, when you can simply open and close a little door??? (On some smaller airboxes, there may not be room for the TPI. In that case, I just use some of those UNI round aibox vents, with duct tape as the "valve". It's not very convenient, but it works just the same.) All very inexpensive.....

http://www.thunderproducts.com/tpi_valve.htm

http://www.unifilter.com/online%20catalog/accessories.html

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One note on the above....

This system is not waterproof! If you are going to be doing stream crossings and the water will reach the top of your airbox, that will be an issue. This has never been an problem for me, seeing that water that deep in a flowing mountain stream would wash me away, so that is something I would avoid anyway. If this were a real serious issue for me, I would just carry a solid airbox lid and install it for the really bad stream crossings, then pull it off and put the vented one back on to procede down the trail.

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