I am pretty new in the ATV world and new to the forum. My 2005, 350 bruin has lost lots of power since I bought it. By lost power, I mean that I hit the gas and it does not react immediatly. It hesitates for a moment before strarting to move, and it never reaches the speeds as it used to. It starts OK and idles OK but when it comes down to moving, it does not have the power. I mostly use it for hunting and plowing and it doesnt have the power to move the snow. I gave it a tune up in the fall and it had alot of soot on the sparkplug. If anyone can help me I would be very appreciative. Thank you.

 

I'm no mechanic or anything...have you adjusted or had your valves adjusted? Your plug was black your saying? If I'm not mistaken that means your fuel is too rich. Have you adjusted your fuel screw or messed with the jetting? If you answer back I'm hoping that someone else will have more of an idea on how to help you.

 

I adjusted the throttle screw and even though it changes the idle to faster or slower, it does not affect the power either way. As per the jetting I do not know how to proceed. If I could see a diagram somewhere I could probably tincker with it.

 

i kinda had a problem like that ,loss of power my 05 bruin, i had dry weights on my primary sheave, try to see if that is you problem? check your belt wile your at it, see if you have too much oil in it?, i dont know if that helps but thats what i found out when my bruin was acting up,

 

Thanks for the tips. I took the carb appart and found The top diafram busted. It explains the reason it was runing so rich, it cause the air mix to be off whene it kicked into a higher gear, so it lost power and deposited soot on the plug. For less than $25 problem solved.