I have a 2008 polaris 450mxr that I bought a couple months ago that has developed what sounds like a bearing howl in the lower end, it was pretty noticeable today, sometimes even heard through my helmet while riding, it doesnt seem to do it all the time, sometimes when you start it up its immediately there and pretty loud and stays until you shut it off, other times you start it up and its not there, Ive been wrenching on these things all my life but have no experince with KTM engines, any inherent problems with these that would explain what mine is doing? somebody tell me this a common KTM problem and a simple fix and I dont have to do a complete tear down and bottom end rebuild on this thing...

 

Not a common Ktm problem or for any engine as far as any howling goes. Could be a crank bearing,but before I tore the engine apart I'd check the sprague (one way starter clutch) gear for sticking as this is a common problem on starter clutches whether on atvs or cycles when worn. Item#10.Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse

 

yeah thats on the list, Im actually hoping thats what it is although Im thinking its not going to be, its not an exact science but the stethoscope shows the loudest point right down on the right side engine case right at the crank/couterbalancer bearing area, which leads me to believe its one of those, but either way...

the reverse gear cable had been hanging up and i was hoping maybe it was something related to that that would be an easy fix but after doing what research I can online(until I get an actual hard copy service manual) it doesnt look like thats going to be a suspect, it obviously isnt the water pump either, and it doesnt appear to be coming from the clutch area or anywhere in the top end, and I cant think of anything else outside the cases that would cause this...

thanks for your help, like i said, I have no experience with KTM, but its just a basic engine design, I think this is one of those cases where deep down I know whats going to have to be done here to fix this, Im just wishful thinking... if you think of anything else by all means let me know, Im going to pull the case cover off and see if theres any telltale signs of a bad crank bearing but I maintain a fleet of about half a dozen atv's in my group so Im not tearing too deep into this one any time soon

 

You should be able to tell on the sprague clutch. Should free wheel without much resistance one way, lock up the other way. Hope it's as simple as the starter clutch galling and sticking. Not too hard to replace if it is.