My 99 Big Bear 350 is making a LOUD tapping noise and it seems to be coming from the head. It doesn't seem to effect performance though.

What do you think it is?

Valve adjustment. If you let it go to long then it will mushroom the top of the valve which then you will have to rebuild the head. Tolerances are .002-.003 on intake and .004-.005 on the exhaust.

I've adujusted the valves and it didn't change. I'm leaning more towards the timing tensioner or the lower sprocket now.

I pulled the tensioner and it looks good. I have slack on the timing chain even with the tensioner is fully extended.

Sounds like the chain is wore out along with both sprockets and chain guides if im thinkin right the bottom sprocket is part of the crank and cant be replace with out replacing the crank. Also might as well rebuild the head since you will have to take the top end apart.

Yeah, I finally broke down and took it to a mechanic buddy of mine. He's cracking the crank case open today and getting started on it. I'm gonna go ahead and bore the cylinder and rebuild the head too. I've got a 2nd Big Bear just like, same year, same everything, same problems basically. I think I'm gonna go ahead and do both of them. Both 4-wheelers were given to me so if I end up spending a little money on them I'm cool with it.

Yeah, I finally broke down and took it to a mechanic buddy of mine. He's cracking the crank case open today and getting started on it. I'm gonna go ahead and bore the cylinder and rebuild the head too. I've got a 2nd Big Bear just like, same year, same everything, same problems basically. I think I'm gonna go ahead and do both of them. Both 4-wheelers were given to me so if I end up spending a little money on them I'm cool with it.

You should do at least one yourself so next time you have a problem with them you will be more familiar with the engines and more likely to do it yourself.

You should do at least one yourself so next time you have a problem with them you will be more familiar with the engines and more likely to do it yourself.

I talked to Lyle (mechanic) about what he found as he dug a little deeper. A new chain can be installed by removing the flywheel. You don't have to remove the crank. If you've got a flywheel puller it's pretty straight forward. I'll do the 2nd one myself if that's the case.

Depending on how worn the chain is that is probably a bandaid fix be sure and check the teeth on the crank or else you'll be doing it again in half a year at most. Doing the rebuild is easy you can do the complete R&R in a day with rebuilding the head and all.