I just bought a 2001 Wolverine. It is very good condition. I changed the oil and filter the other day and I noticed the valves are noisy. I adjusted the valves and that did not help. I am running castrol 10W30 oil. I don't know what weight oil the previous owner was using. Could it just be the weight of the oil that is making the valves noisier now? My son has a 2003 Wolverine and his is alot quieter than mine. Any help is appreciated. Thank you

 

I don't see how it could be the weight of the oil. The yfm 350 engines are just noisy by nature because they have 2 large valves instead of 4 small ones like most engines its size. As long as you know the valves are adjusted to spec, and there's not an aftermarket cam in it (different specs), I wouldn't worry about it. The most i'd do is run a compression test and make sure the valves aren't leaking.

 

In cars I have seen the lighter oil make a difference in the noise an engine makes it is an old car dealer trick to take and put about 1 qt of 80w90 in a motor that is knocking or with bad valve noises to sell it and then when you change the oil they say it is caused my the oil change place.

But with the yamaha motors they do tend to be a little noisy in the valve department. But it is usually nothing to worry about.

 

Thank you for your replies. I got to looking at my shop manual and decided I should recheck the valves. After I took the bike back apart I looked up the valve clearance and relized that I was reading the feeler gages wrong(looking at the inches instead of mm's). Once I fixed this and reset the valves using the gages as mm's instead of inches the bike is much quieter. My wife always tells me I must like doing things twice.

 

haha, good to hear you got it figured out.