HOW HIGH CAN CAM TIMING JUMP?
RZR XP1000 LOOSE CAM CHAIN
A DIRT WHEELS FAN WRITES: “I have a 2015 Polaris RZR XP1000, and lately I have noticed a rattle inside my motor at startup. It seems to be worse when the motor is cold. I was told it may be the cam chain making noise because it is loose and may need to be replaced. Before I have my dealer replace the cam chain, I wanted your opinion first.” – Darin Connor, Colorado Springs, CO
OUR PRO ANSWER: While it could be your cam chain is stretched, it could also be one of the cam chain guides is bad or the tensioner is not adjusting properly. If an inspection shows the cam chain guides to be in serviceable condition, then I would look at the automatic cam-chain tensioner. Here you have several options. You can replace the factory automatic cam-chain tensioner with another factory unit. But be aware of the limitations of the factory unit. Your factory tensioner is hydraulic and only provides the correct cam-chain tensioning when the engine is operating and develops oil hydraulic pressure. Also, the factory tensioner has a small bleed hole in the top of it that can drain the oil from the tensioner if the RZR is flipped over. Upside down with the engine still running will cause a loss of prime in the tensioner, and the tensioner will cease to tension the cam chain. This condition can cause the chain to jump a tooth or two on the cam sprocket which will cause the valves to be out of time and they may contact the piston at TDC (Top Dead Center). Most people manage to keep the shiny side up, so this is usually not a problem. So if you want to stay with an automatic cam chain tensioner, you can go factory or with an aftermarket automatic tensioner like the Weller automatic cam-chain tensioner here: https://www.wellerracing.com/TENSIONER-ASSY-CAM_p_4552.html. Or you can go with an automatic tensioner that is mechanical automatic tensioner like the Alba Racing tensioner that uses an OEM Yamaha automatic ratcheting tensioner here: https://teamalbaracing.com/i-21279173-armat-by-alba-racing-automatic-cam-chain-tensioner-polaris-570-900-1000.html. The advantage of the mechanical automatic tensioner is the elimination of the start up noise caused by the OEM hydraulic tensioner. And the unit also maintains tension while vehicle is shiny side down unlike then hydraulic OEM tensioner. Is this the best tensioner since the invention of sliced bread? Yes and no. Yes, they work quite well but the tiny internal teeth can become worn down and start to make noise, indicating replacement is necessary. Finally, we have for your consideration door number 3! The Alba manual cam-chain tensioner that you must set the cam chain tension manually as the cam chain stretches from use, available here: https://teamalbaracing.com/i-13567514-manual-cam-chain-tensioner-rzr-570-900-1000.html. Too many choices is either a good or a bad thing, Son!
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