Hi there. I'm new to the forum but not new to ATV's. I have a 1995 Sportsman 400. It sat for a year with Carb issues that I got tired of fixing and having someone else break. (It is stored at my fathers farm). I got a call from my father that my nephew got it running then it quit and he took it to a mechanic. Mechanic said the engine has a hole it in and is no good. The oiler propably went bad. I get it back, the hole is in the crank case. It looks like the counterbalence somehow came up and hit the case knocking a hole in it. When I turn it over I can hear the counterbalence rub the case as I see it pass by the hole. The dip stick shows the case is full. I was wondering how this could happen and what besides the case am I looking at replacing. Is this somewhat normal or do I have another one of a kind problem.

Thanks for the help

Ken

 

Welcome to the forum! Most of the broken cases I had were from broken piston skirts or crank bearings that separated and that got under the crank that broke cases either at the bottom of the cases,at the back or even at the front toward the counter balancer. But not over ruling a counter balancer bearing failure at the front or rear of the balancer or part of the balancer gear or the crank gear that could have tangled with the balancer. Oil pump drive gear is past the back balancer bearing and the balancer cavity, only way to affect the balancer if it broke off or froze. Have you had a chance to tear it down yet? Lot of it depends on how big the hole is to whether you can repair or not. OPT

 

Thanks for help. The hole is in the top of the case. If you take the carb off you are looking right down at it. It is about 2" long and 1" wide and is right where the case seams but all on the outside portion of the case. I have not taken it apart yet. I was trying to find out what happened and how big of a job it is going to be. What do you think, is it worth fixing, putting a used engine in, or parting the thing out.

 

The only way you can find out is to tear it apart and see how much damage not just to the cases but to the rest of the engine! Whether the rod and crank bearings need replacement, piston assy,etc along with how bad the case damage is. Can get costly to rebuild plus either trying to repair existing cases, trying to find a used one,or purchasing a new set! A new set of cases with bearings and seals is over $430! Plus if you go that far,might as well completely rebuild the engine! You have to decide how much you are willing to spend on repair. I came across this a lot of times on the older machines that had damage and if a shop does the repair,probably will be more than the machine is worth! Your labor could reduce the costs,but may still need to have the crank rebuilt,cylinder bore,etc. OPT