03 Polaris Sportsman 700 engine knock / tap video #2

Apr 3, 2013 • 03 Polaris 700 4X4 that has been on fire and has burned up wiring -Show more

I installed a used wiring harness, checked for spark, no spark, read through the repair manual and things weren't adding up, at first I thought the year was wrong because part numbers and wiring connections were incorrect for this model and year. I did some on-line research of part numbers from the ignition box and discovered this Polaris has the upgraded Ignition system from Ducati to "Kokusan ignition". So I downloaded the installation instructions, wired ignition correctly, got spark, attached an auxiliary fuel tank, got it started and it knocked.. I removed the clutch, noise still there. Removed valve cover and inspected valve train, all good. Ran ATV with valve cover removed to make sure it was getting oil to the rockers, and it is. Removed the R/S cover and flywheel, checked the stator and mounting for improper installation, all looks to be intact and in working order. Last check will be later today. I will remove the R/S stator assembly and then the R/S gear case to inspect the counter balance shaft, cam, oil and crank gears to see if there are any issues. If not, I may have to pronounce this a bad crank.

Update: I found some slop in the counterbalance shaft and crank gears. I was hopeful that was responsible for the noise. After removing the balance shaft gear so I could just rotate the crankshaft by itself, I was able to determine it has a "bad rod bearing on the #1 cylinder". With the spark plug removed from the R/S #2 cylinder there is an obvious, but slight clunk when rocking the crankshaft against the compression of the L/S #1 cylinder. When I remove the #1 spark plug, install the #2 plug and rotate crankshaft against compression, the clunk is very faint and almost indistinguishable...

As a final conformation, I put a long thin screwdriver down through the spark plug holes to the top of each piston and rocked the crank back and forth, there is definitely a rod bearing out on L/S #1 cylinder...