Well after my sputtering issue from
here, my kids RZR 170 started to develop a knock. Came after a wide open throttle run at no load (back wheels in the air).
Took me a while to have time to look at it, but finally got the engine torn apart. What I've noticed so far:
1.) It wasn't the CVT belt or clutches as the noise was there with all that disconnected.
2.) Drained oil and
thought I saw gold metal flakes in the oil which would be indicative of a rod or crank bearing going bad in nearly any car engine.
3.) Tore everything down and found this engine uses ball bearings for crank and needle bearings for rod (lesson learned, look at a repair manual first). Both of which seem perfectly fine, no rough spots at all and no excessive play.
4.) Measured side to side play on the rod to the crank and measured .008" of play, well within the allowable tolerance of .0039" to .011".
5.) Noticed a lot of carbon buildup on the top of the piston and the cylinder head. I don't run the Polaris additive.
Next things I'm going to check:
1.) Balance shaft bearing seemed rough at first, but smoothed out when spun by hand. Might have been rough as some dirt may have gotten into it during disassembly.
2.) Timing of the balance shaft to ensure it's in time. I read another thread that said to check for a sheared or partially shearing timing key that throws off the balance shaft and makes noise.
3.) Camshaft bearings, though they didn't seem to be a problem when I took the camshaft out.
If all checks out fine then there's really nothing internal to the engine that would cause a knocking problem and I'll reassemble the engine.
Only thing I'll do extra is clean off all the carbon on top of the piston and cylinder head as maybe I was getting detonation. I did fiddle with any adjustment screws that I could find on the engine to try and get it to run correctly (when it was sputtering), but thought I had only changed one thing at a time and changed it back when it didn't help. Only thing with that is being an EFI engine I can't really change Air Fuel Ratio at all, the computer handles that and if something is out of whack it should go rich to save the engine.
About the only thing that could potentially affect the AFR is the fuel pump I replaced, maybe the new one is going bad already and it not providing enough fuel pressure to the injector. Though last I remember the plug looked fine, I'll have to check again.
Any thoughts or things I should check/look at before I reassemble the engine?
Thanks
