Output shaft case housing crack?

[2001warrior]

I was told by a fellow tech at work that the case cracks around the output shaft, if mods are made to the engine. He has owned sevral warriors and worked on sevral and they all cracked the case at the same place. Wondering if this was a common issue or anyone has seen or heard of this too?

 

[Guest]

the only time i've ever heard of cracking the case; is when the chain brakes or pops off the rear sprocket and the chain slaps the case

 

[yamarider]

That's a load that they break at the output shaft due to increasing the power. Sounds like somebody just trying to steer you away from modding your warrior. It's not uncommon to find a yfm350 with the case damaged around the sprocket, or any off road chain driven engine for that matter. It's caused by the chain coming off the sprockets and busting the case up 99.9% of the time, because of improper maintenance. Engine mods aren't even a factor, a stock one will throw the chain just as easily if the chain or sprockets are worn, improperly adjusted, out of alignment, rollers and guides worn/damaged/missing, etc., and that's something that can and does happen to all chain driven engines like this when they're not taken care of properly.

 

[DeadLastRacing]

^ what he said, and you notice it more/it does more damage on the warrior because of how the case is formed and how the carrier and swinger work. The back side of the chain guard is part of the engine case and the carrier slides the the swinger (not like modern machine where the carrier is offset and rotates) so the chain gets looser easier and more frequently if alls not tightened to sepc in the rear.

I bought a guard from noss machine and the way its designed, takes care of any worries. Plus I make sure my chain is always taught before I go out and ride.

 

[2001warrior]

Sweet! I didnt see how that would affect it either, but im new to atv's. I appreciate the help.