Polaris RZR 900 Flywheel Timing Mark is Off

What could be the problem when the flywheel timing mark doesn’t line up on a Polaris RZR 900 side by side engine? Could it be a poorly installed woodruff key?

Our resident Polaris UTV expert John Talley does live Q&A on our YouTube channel every Friday at 3pm Eastern, and in this session, John was asked if a flywheel timing mark misalignment on a Polaris RZR 900 engine could be attributed to an improperly installed flywheel and woodruff key.

Polaris RZR 900 flywheel timing mark

Polaris RZR Flywheel Timing Mark Not Lining Up

I’m working on a 2011 Polaris RZR 900XP that’s been bored out. I’m trying to set the timing. I’ve left the cylinder at top dead center. I have my intake and exhaust cam set as they’re supposed to be, but the flywheel timing mark isn’t lining up where I think it’s supposed to be. It’s the one on the left-hand side where the crankcase line is, and that’s where my cylinder is at top dead center. When I try to start it without any plugs, it rolls over perfect, but when I put plugs in it, it spins and clunks. Could the flywheel and woodruff key be on improperly?

John Talley: Well, that’s a bit of a longshot, but depending on what happened to the engine that you had to rebuild it, if you didn’t replace the woodruff key or remove the flywheel — I don’t know how far you went down into the engine — if the engine locked up, let’s say it had a mechanical issue and it just locked it up. Well, it’s got the momentum of that flywheel, and it’s been known to shear the woodruff key. I mean, it’s still on there and it’s still tight, but it’s probably moved 5, 10, maybe even 15 degrees and that may be what has happened with your particular machine. So I’d say pull that flywheel off, make sure it didn’t shear the woodruff key, and then go from there. That sounds like what you’re running up against. I wouldn’t spin it over anymore because chances are you’re going to bend the valve. That kind of concerns me when you say it spins it and clunks.