Over the winter my Bruin 350 started knocking pretty bad. It knocks pretty bad when you first start it and then quiets down a little bit after it warms up. However you can still here the knocking. I am scared that my motor may be shot. Its starting to warm up a little bit so it is time to get it fixed. Any suggestions what it might be and how hard it maybe to fix?

Thanks,

 

Have you ever had your valves adjusted? If your valves are out of adjustment they can rattle.
Do you have oil in the motor, ever been really low? Aprrox how many hours are on the machine. Ever submerged it to where water may have gotten into the engine. Check the mounts to the motor, are they weak? Sound like its coming from the top end?
Sorry for so many questions, but I'm hoping for your sake its a valve adjustment you need. Which you should either have done, or do yourself around the first 20 hours. Does is still run good or seem to be off?

 

i know the yfm350 motor is notorious for valve knocking, no matter how many times i adjust my valves the knocking is there. its not so bad where i think theres something wrong though. im willing to bet its your valves.

 

Never had the valves adjusted. Never ran it low on oil. I would not know how to guess the hours, I know it is over 20 but it does not get used all that much. It does sound like it is coming from the top end. You can hear it up there. Have not used it since I heard the noise but I think it is still running pretty good. Thanks for all the information. I will see about getting the valves adjusted this week and see what happens. Once again thanks for all of your help and pointing in a direction to start.

 

If its something you don't want to try yourself, around here in Western MA one dealer will charge $250 to adjust brakes, clean carb, adjust valves, change fluids etc. The other will charge $150. So I would shop around if you have more then 1 yamaha dealer close to you. If you plan on doing it yourself I would buy the service/shop manual. One dealer quoted me $75 and I called Ronnies and I got one shipped to me for 45 plus $5 shipping. Shop around on that also. Good luck.