Thanks for this video. I just bought a '98 Big Bear 350 with the same starter issue. The seller included a new starter that didn't fix it. He also included both one-way bearings. I'm going to start with the left side of the engine since that's what ultimately fixed yours. If not, then it's on to the right side. The '98 is a bit more complicated because they moved to the 5-speed semi-automatic so the shift linkage is a little different, but your video helped tons with my diagnosis.
The sprag clutch (one way bearing)on the centrifugal clutch has nothing to do with starting. It’s purpose is to allow the bell of the centrifugal clutch to rest at idle thereby disengaging the crank from the clutch pack.
so specifically then it's the sprag clutch on the opposite side of the clutch pack that went. (In this case both were bad so I had multiple issues but if the starter is spinning it's the sprag on the left side vs the one in the bell housing.) Thanks for the insight.
The throttle needs to be wide open when doing a compression test. I'd assume that is why it is showing such an extremely low reading. The minimum compression for it to run should be 100 psi.. and it would run extremely poor at that psi. 160 is the ideal psi for the 350 big bear, 350 wolverine and 350 warrior. I'd check timing and valve lash before taking the head back off next time. A valve lapping never hurts but with that amount of compression missing it would be a bent valve not just a seal.
I have the same ATV, and it also only gets one spark when you start cranking. I have been fighting it off and on for about a year. I guess it's time to find another harness. It died 5 minutes after I pressure washed it, never again will I pressure wash an ATV!
My best guess on this one... was still the stator. I ended up swapping the harness, cdi and stator to make the 1990 harness work. I still think I had a bad stator that was passing resistance checks but I can't be 100% certain sadly. Wish I pinned it down to one part. Pressure washed it... any chance there is water in the stator bay or would that be too easy at this point. (I had that happen on one of my blasters.)
Compression is now 125. Turned out I had to retard the timing one tooth after putting the new timing chain in to get it to start reliably. It had been dead TDC after the new chain but was still kicking back the engine occasionally during cranking and coughing out the intake. Seems good now. We will see. :)
mine did the same thing i was riding when all the sudden it shut its self off went to crank it back over and she just spon took the fly weal case off and there it was all broken up.
After replacing the one way bearings I swapped down to a 5w oil from 10w. Since then it has been running like a champ. 5w is within spec in the manual and I found that the starter could crank the motor faster cold putting less strain on the one way bearings.
