Loss of power; Rancher 55

remove the muffler and try running it if ok open the muffler and clean off the screen

The 50/51 and 55 always had the same bar mount, the bar was part no. 508912164 for 15" 508912172 for 18" and 508912180 for the 20", the oil is not fed through the bar adjuster hole.

Hi Chris,
Check the air filter is clean and the choke plate is working ok.
Ensure the chain is sharp.
Check the chain isn't damaged and dragging in the guide bar.
A blocked muffler/silencer can cause loss of power.
Try screwing the "H" mixture adjustment screw in with the engine running at full power to reduce the richness of the mixture. Do this 1/4 turn at a time. Ensure you count the number of turns so you can get back to where you started.

The plastic carb mount has a hole and a slot, this is the pulse channel from the cylinder to work the pump diaphram in the carb, if you look behind the plastic plate there is a tube that fits into the cylinder under the black induction rubber, this feeds a positive and negative pressure to the carb as the piston rises and falls, make sure you have re fitted the small seal in the cylinder that seals this tube or you will have big running problems.
Let me know if you need more help.

Check the fuel filter, air cleaner, and muffler for plugging. Check the fuel lines for decay or other damage. Make sure the chain/bar is properly lubricated, sharpened, and tension adjusted. If no help, turn the H jet screw CCW a little so that the engine 4-strokes at speed unloaded, but immediately 2-strokes when cutting. This will give the most power and least heat. Hope this helps!

WITH A SMALL SCREWDRIVER ,SCREW BOTH HIGH AND LOW ( H&L)SCREW IN TILL THEY BOTTOM OUT ,NOT HARD, BACK THE H SCREW OUT 1 1/4 TURNS AND THE L 1 1/8 OF A TURN START IT UP ,TAKE TO MAX REVS,PROBABLY BEST TO HOLD CHAIN BAR IN VICE SOTHE CHAIN RUNS FREE,THEN TURN THE H SCEW IN AND OUT UNTILL IT RUNS THE FASEST AND SWEETEST THEN BACK IT OFF 1/8 TH OF ATURN LET IT IDLE AND DO THE SAME WITH THE L SCREW,YOU MAY HAVE TO ADJUST YOUR IDLE SPEED NOW, BUT THEN YOU SHOULD BE RIGHT

Don't continue to try for high speed operation until the problem is rectified. Look for loss of chain oil or the chain is too tight. If it is equipped with a chain brake, make sure that it isn't dragging on the clutch rim. (It would be very hot or blue colored.) If no oil, remove the bar and chain--run the engine and watch for oil coming out of a port near the sprocket end. If it does so, clean the holes in the drive end of the bar, especially the small holes that connect to the chain track slot. Adjust the bar to tighten the chain enough that the chain doesn't begin to droop from the bar, yet turn freely by hand. If no oil comes out of the port, then the oil lines or the oil pump are/is faulty. Be sure to use bar oil only in the tank?

Preset both needles about 1-1/2 to 2 turns CCW from CW stop. Set H needle first after warm-up. At high speed, engine should 4-stroke with no load, but smooth out with light load(cutting wood). Set idle speed so that it will keep running, then adjust L needle so that engine tries to follow the throttle, but idles fairly smoothly. Readjust idle speed so that the clutch is not trying to drive the chain.

Cleaning the exhaust: on the saws I've worked with it was just to loosen two bolts at the front and then the exhaust is off the saw. Clean with brake cleaning fluid and blow with compressed air, let it dry before assembling. Don't forget to clean the fine mesh at the output side underneath the lid if present (i.e the spark arrestor).

Make sure to have your carb adjusted properly afterwards.