i have a 05 yamaha bruin 350 2x4 it starts up fine and runs fine, but as you go it will make it up about 30mph and wont go any faster ,but it will continue to rev higher as you push the throtle in more, the govener is not on, it has a new belt on it, i was wondering if it could be the cdi box? i have called yamaha thay had no clue and all the sevice people had no clue. please help!!!!!!!!!! thank you patrick

 

I dont know the answer to your question but who installed the belt? Maybe it wasnt installed/tightened correctly? I havent opend up my belt/case yet so this could not even be a logical question.

When you say governor to you mean the throttle screw is out all the way?

 

i put the belt on, but it was doing this before i put the new one on , sorry about that i met the throttle screw and yes it is all the way out

 

Did you disassemble the primary pulley and clean and relube the weights?

 

i was working on the bike today to pull of primary sliding sheave assembly and the nut holding it on the 7/8 one will not move!! do you have any hints to help me get the nut off it would help me out alot. thank you patrick

 

never mind i got the nut off .

 

Most of us get it off with an air impact wrench, but youre gonna need to torque the nut to about 90 ft lbs when you install it.
Check out picture number 11 in my gallery, it shows how to wrap a strap around the pulley and attach to the frame so you can use a torque wrench to tighten the nut.
Dont skimp on the grease, it takes one ounce per weight, and make sure everything is cleaned out, before greaseing. The old grease is gonna have dirt and other contaminates in it, and you want all that crap out of there.
This should restore your top end speed.

 

i pull off and cleaned and greased the primary pulley and it sounded better but it did not fix my problem so im going to try taking the secondary pully all apart to see if that is the problem, if any body knows what else that could be the problem please let me know, thank you patrick

 

ok i cleaned and greased the 2 pully and checked every thang the spring and every thang is good ,i put it back on and the problem is still there. could it be the cluch? but i would not think a auto cluch would go out ,or even if that would cause my problem, please help if you know thanks

 

What type of oil have you been using for oil changes? Does it have the star burst, energy conserving label on it?
Hows the oil level? and when was the oil changed last?