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Hi there, I’m new to this forum but it looks like there is a wealth of knowledge here so I figured that someone might have had this problem before and could help. I’m fairly new to owning ATVs and carburetors in general but I have a very good automotive background. That being said, this bike ran great when got it 8 months ago and was told recently that 110 octane / airplane fuel is the best way to keep ATVs out of the shop due to carb issues due to less bad ingredients in higher octane gasoline. So the bike ran great for like 3 tanks full of 110 octane (2 months of running directly after a carb rebuild done by a local shop) then all of a sudden when you give it throttle in any gear or N it will bog for 2-5+ seconds then finally take off. I took it back to the shop and left it with them for a week and they went over bike and could indeed duplicate issue but said it was the 110 octane and to use regular 87 octane on that one due to it is a lower compression motor. THE PROBLEM STILL EXISTS even after drained tank and filled with 87 octane and have gone thru another half tank so far.

Is it the gas that is the problem still? I would think a half a tank should be enough to flush it out. The bike just screams after it finally gets out of idle so I have no idea what it could be. Thank you for any and all possible solutions and information!!!

- Adam in Phoenix
 

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two strokes typically bog from idle to about 2000 rpm - it's referred as to the start of the power band.

110 octane is too high and 87 ethanol is too low you should run 89 to 91 octane non ethanol fuel, but it will still bog when the throttle is opened suddenly from idle to around 2000 RPM.
 

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Discussion Starter #3
two strokes typically bog from idle to about 2000 rpm - it's referred as to the start of the power band.

110 octane is too high and 87 ethanol is too low you should run 89 to 91 octane non ethanol fuel, but it will still bog when the throttle is opened suddenly from idle to around 2000 RPM.
 

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I'm sorry, I didn't pay attention to the model - I just saw 2001 model and assumed two stroke.

Well, it can hold true for a four stroke also, but it is a characteristic of a the two stroke.

When a 4 stroke bogs, it's caused by a vacuum drop upon throttle opening - that's one reason for the CV (constant velocity) carb. The slide in the CV carb is supposed to drop upon throttle opening to keep the velocity of the air flow constant in an effort to reduce throttle lag. If the internal vacuum passage that affects the vacuum diaphragm has been altered by improper cleaning, the return spring is weak or another calibration orifice/passage is damaged by corrosion or modification, then the slide may not operate as designed and that could result in a lag. My Keihin carb has an accelerator pump which gets it past the vacuum drop phenomena. About the only thing you can do short of correcting the calibration of the carb is to increase the idle speed to reduce the lag and changes in changes in fuel will affect jetting too.
 
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