Chainsaws

Brad,

Just a couple of possibilities to check. Also I am Not a Husqvarna Representative or a Repair Service but I have Seven of these Model 455 Ranchers, and I have never had a problem, and I do analytical diagnostics of these chainsaws. So I am always looking for the real problem child but there usually is a good reason. So here is my list of things to check:

1. Since the Model 455 is available to run different pitch bar and chains, Its very important that everything is compatible and Not mis-matched. The two pitch sizes that are available are listed in the owners manual, and are .325 pitch, and 3/8 pitch. So starting at the drive sprocket under the clutch cover, you need to check which pitch is the drive sprocket (.325 or 3/8) ? Next everything after the drive sprocket must be the same, "You cannot Mix and Match different pitches". So check that the Bar is stamped or stensiled with the same pitch size as the drive sprocket. And Finally the Chain pitch must also Match the drive Sprocket pitch, and the Bar Pitch, They all must be the same or the chain will come off the bar, In addition the chain has a Gauge of the drive links, this Must match the gauge of the bar ( typically on a Model 455 the gauge is .050 ") but there are other gauges and you cannot have a mismatch of this either. I have seen this mismatch problems several times on chainsaws that I repaired.

2. When a chainsaw is shipped from factory to a Dealer, it may be shipped with just the power head, then the dealer adds the size of the bar and chain that you want, or sells them separately. However, when the Power Head is shipped separately, there is typically a plastic spacer or sometimes looks like a styrafoam washer Installed over the bar bolt, and under the clutch cover. The purpose of this "Shipping spacer" is to hold the clutch cover in place during shipping, these are to be removed and discarded, or put into your tool box in case you ever need to ship your chainsaw without a bar and chain installed. I have on occassion seen individuals, homeowners, and maybe Dealers too, that forgot to remove this shipping spacer, and then Installed the Bar and chain on top of the spacer, and tightened up the clutch cover. So its very Important that the original shipping spacers, have been removed, Please check. The bar and chain should fit flush against the crankcase, and then the clutch cover should fit flush against the bar and chain, and "NO Spacers" or anything in between. If the alignment is off between the drive sprocket, the bar, because of a shipping washer still installed,  then the chain will Not stay on  the bar. So Please check.

3. Finally a chain when moving on the bar at a high rate of speed Must have Oil to keep the bar and chain lubricated, and to make it easy for the chain to ride on the bar rails. Make sure your bar is getting plenty of oil during use.

I hope this helps, and Please post if you find resolution to your problem. I am very curious as to what could be the problem.

Karla