Son Of Mack
New Member
So my buddy smoked this saw originally by running straight gas in it (like a dummy) and blew up the crank bearings and part of the bottom of the piston. He got a quote for a repair and which made him *pucker*, so then he just gave it to me because I love tearing things apart. So I pulled it apart and found the crank bearing race let go and spit out all the ball bearings which then got tangled up between the crank and piston and made a mess so at minimum it needed a new crank, bearings and a piston kit put in it, but I didn't replace any of the other seals or the head/cylinder because they looked "ok" to me, I mean this saw was only a few months old. I got it all cleaned up and back together "running" but it seemed to put out a fair amount of excess smoke, bogged down and had poor throttle response. Tried adjusting the high/low on the carb and that didn't help, I searched online and found the muffler mod for the 455, that didn't seem to help either. I gave up and let the saw sit for a couple years. Then recently I decided to give it another go but just made it worse, it was still running sluggishly with poor throttle response so I adjusted the carb idle speed screw. Then it would only start with the throttle open for awhile and now I can't get it to start at all... 
So far I've found two different initial carb "starting settings" for the high/low but no initial start point recommendations for the idle set screw. The most common one where you run the high/low set screw adjustments all the way in and then back them both out 1.25 or 1.5 turns and another that said 2.25 to 2.5 turns out which was more "specific" for Walbro carbs. I've tried turning the idle speed screw out 1/2 turn at a time with the high/low set to the initial settings both ways. It has spark and the compression is at 80 psi. The lower crankcase seals are probably shot because the saw leaked on the floor when it it sat for awhile so I'll be replacing those. Also seems it doesn't have the best seal around the spark plug because it weeps a little unless I really crank the plug in hard. What's the right settings to start out with for the high/low and idle for this saw and what else could it be? Just "old" mixed gas, a bad head with low compression, crankcase seals, primer bulb? Thanks in advance!
So far I've found two different initial carb "starting settings" for the high/low but no initial start point recommendations for the idle set screw. The most common one where you run the high/low set screw adjustments all the way in and then back them both out 1.25 or 1.5 turns and another that said 2.25 to 2.5 turns out which was more "specific" for Walbro carbs. I've tried turning the idle speed screw out 1/2 turn at a time with the high/low set to the initial settings both ways. It has spark and the compression is at 80 psi. The lower crankcase seals are probably shot because the saw leaked on the floor when it it sat for awhile so I'll be replacing those. Also seems it doesn't have the best seal around the spark plug because it weeps a little unless I really crank the plug in hard. What's the right settings to start out with for the high/low and idle for this saw and what else could it be? Just "old" mixed gas, a bad head with low compression, crankcase seals, primer bulb? Thanks in advance!
