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Discussion Starter #1
My Raptor 660 will shut off if I'm going down hill, and sometimes will shut off if I hold in the clutch and come to a complete stop. Other than that the quad runs great. Also if I have it running and sitting in neutral 30sec to a minute later it will just shut off. Previous owner said he bypassed the rev limiter or something, could there be a problem with that? It has been flipped before, and I read something about a lean angle sensor? I don't know if its an electrical problem or maybe my air/fuel mixture needs adjusted, or my idle. My starter just got replaced, but it did this before that. Any help would be very much appreciated!
 

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Master of the Electron
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Problem related to reverse limiter bypass? NO
Problem related to a non-existent lean angle sensor? NO
Problem related to carbs - dirty float valve - dirty pilot jets - plugged cap vent, etc., etc. - MOST LIKELY.

1st turn up the idle speed a bit and see if it stops dying while just sitting at idle. (I assume it restarts immediately after this happens, right?)

2nd, if the other problem is due to going downhill, the float level may be set incorrectly causing the A/F mixture to change with the angle change.

AND - Welcome to the forum!
 

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Discussion Starter #3
Do you know if the floats should be set higher or lower? Right now it sounds like its running rich
 

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Master of the Electron
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I can't tell you... ride it with the fuel petcock turned off - as the float bowl empties does the problem get worse or does it briefly get better? If better then it is too rich so too high... if only gets worse then it's too lean/too low.
 

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Discussion Starter #5 (Edited)
Thanks for responding, It sounds worse with the petcock turned off it starts to idle extremely high and run like I'm holding the throttle in one spot. But with the petcock turned on I barely rode it for 15min and its overheating really fast, starting to have a bad gassy smell and a little bit of black smoke coming out of the exhaust. Also when I rev the engine and let go of the throttle the rpm's stay super high and after like 10 seconds it will finally drop back down to a normal idle. I also noticed it idled and ran better with the choke on. Do you think I need bigger jets?
 

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Master of the Electron
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Your symptoms don't all agree - the long time to come down to idle suggests lean, but the smell and black smoke suggests rich.

Since you just got the quad I suspect your carbs need a good, thorough cleaning... pilot jets are probably plugged causing lean at idle and slow return to idle, and leaking float valves are probably causing overfill/overflow of the bowls causing the fuel smell and black smoke...

What makes you think it's overheating?
 

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Discussion Starter #7 (Edited)
I thought it was overheating because the red engine light will come on and off after like 15min of riding and the engine and exhaust pipe are extremely hot just after those 15min. It just seems like it shouldn't be getting that hot that quick, unless thats just normal. During that time I'm not hammering on the gas or anything and I didn't go above 3rd gear. But I will go throw and clean everything. There is also very noticable hesitation in acceleration in every gear when I shift.


(sorry I should've metioned this before but it does have a yoshimura pipe on it, I bought the quad with it on there)

would bigger jets make it run leaner or richer? Or should I not change the size?
 

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Master of the Electron
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Does the fan come on? It should long before the red light does... fan should come on around 208F and the light at 248F. If the fan isn't on when the red light is on then the fan circuit needs work.

BUT, the cooling system works well enough (when working properly) that the fan should only be necessary if you're at idle for a long time, moving around VERY slowly or pushing the quad REAL hard for a while... so, if it's overheating (red light on) while riding normally, the cooling system (radiator, thermostat, water pump, fan) is having issues and needs a good looking at.

Is the airbox intact or open/modified? Without knowledge of airbox and exhaust mods and what main and pilot jet numbers are currently in the carbs, we can't tell you whether a change might be necessary.
 
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