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Discussion Starter #1
Dose any one no what Midrange Lean Condition means??
 

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This usually means your engine is getting an incorrect fuel/air ratio when your throttle is about half-way open (midrange).

To explain:

Your carb spits out a ratio of fuel-to-air which is ideal for maximum power, yet still safe for the engine. This is known as the stoichiometric ratio; in which the fuel and air are perfectly atomized for proper burning of all the fuel.
If this ratio is off, it is refered to as either a "lean" or "rich" condition. "Rich" is where you have more fuel than air, and your engine often feels slow or "boggy", especially on warm days. Running rich is usually the safer side to be on because it will not damage your engine.

Obviously "lean" is the opposite, having more air than fuel. This is often dangerous because your engine can quickly overheat, and maybe seize a piston, or cause other engine damage. But that's a whole other topic.

Since cold winter air is more dense than warm air, you will get flucuations in engine performance on any given day.
On a typical carberator, this is when we would "re-jet" the carberator to adjust for the conditions. On warm days, i may put in a smaller diameter main jet to help regain my correct fuel ratio, and gain some of the lost power. This is why snowmobiles seem to run best when the air temps are really cold.

Many manufacturer's also offer some sort of EFI (electronic fuel injection) to compensate for these differences automatically. Many buyers like this feature for it's convenience; but it's not for everybody.

So a Midrange Lean Condition tells me that something is not setup correctly and simply needs an adjustment. It tells me that your engine is running lean at about 1/2 throttle and it's not a good idea to continue driving it. It could be caused by many things, but most likely it's your carbs. I would start by raising the needle 1 or 2 notches to give you more midrange fuel.

I hope this helps. Although, i probably confused you more than anything. Contact your dealer or service man if you are unsure. Carberators and jetting are a very complicated thing to explain, but we will try our best.

Good luck!

<I should add this is my educated opinion and may not be 100% accurate :) Please correct me if i'm wrong. >
 

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Perfect expanation. Any time you can work {stoichiometric}into a conversation it pretty much meens you know what your talking about.LOL
By the way ac700 midrange lean is much harder to diagnos in the trail setting.Do you have symtoms, or are you just wondering?
 

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If you can use the word in three seperate sentences in one day.......you OWN the word! [:D]

Great explaination MegaMan, sounded right on the money to me.
 

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Discussion Starter #5
I dont know if my sled has it but this is what ive read about this snowmobile which im buying of my father for next season...


1999 Arctic Cat ZR700 - Midrange Lean Condition

Arctic Cat has issued a product service bulletin for 1999 Model Year ZR700's. The service bulletin concerns a possible midrange lean condition and requires movement of the E-Clip position on the carb needles to the FOURTH position from the TOP.

Arctic Cat recommends that only a qualified dealer perform this service.

Contact your local dealer for specific information.


and i just wanted a beater explination on how this afects a snowmobile. thanks though but if my snowmobile did have this condition would it affect speed or acceleration???
 

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well if it hasn,t burnt down yet and he,s been riding it,i wouldn,t worry about it.the lean condition from the needle is ussaally from cruising at a constant speed,a sled in tight trails on and off throttle would never be a problem.
its easy to check have buddy come over who knows how to check the needles.probably already been done.should be in the 4th groove from the top
 

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if you are lean on the mid range the sled will give a slight hesitation or pop when going from partiall throttle to wide open.
 
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