SandMan
ArboristSite Lurker
Read a lot about 066's and muffler mods but didn't see anything to answer my specific questions. Here goes...
Bought and fixed up an 066 Mag for pretty cheap, $260 including $20 in parts from a member of this site (thanks!). Compression was good and the piston and bore look great. I assume this is the later model as it had the puny 3/8" muffler outlet. Due to a small leak and the restrictive outlet, the plastic parts near the chain brake links had cooked, including the hand guard bearing boss. Being the lowly weekend warrior, fixing the chain brake was a must for me- no telling what may lurk in the old farm trees I get for firewood, particularly from fence-high level to stump.
After getting everything fixed, I cut out the goofy muffler 'catalytic' box and opened up the outlet to approx 3/4". When checking the H/L screws, they will only open 7/8 turn for the high and 3/4 for low. The shop manual and (I think) a few posts on this board recommend starting out at 1 full turn open. Putting aside the screw issue, Stihl recommends for the 066 12,000 rpm max with bar and chain. A Madsen's article I read recommends 13,000 rpm max w/o bar & chain.
But what about post muffler mod? Should I adjust for a higher max rpm? I would assume so- but what is my target rpm after the mod? I have a tach, so checking this won't be a problem. With the H screw all the way out (rich), I do get a little burbling at full throttle. I should have checked the pre-muffler mod rpms as post-mod it sounds much higher at full throttle.
Hopefully I can make the adjustments I need with the limited screw travel on the carb adjustments. I had not heard/read about stops on 066 screws- so I don't know what's up with that. Thanks in advance for your help, great site here.
Bought and fixed up an 066 Mag for pretty cheap, $260 including $20 in parts from a member of this site (thanks!). Compression was good and the piston and bore look great. I assume this is the later model as it had the puny 3/8" muffler outlet. Due to a small leak and the restrictive outlet, the plastic parts near the chain brake links had cooked, including the hand guard bearing boss. Being the lowly weekend warrior, fixing the chain brake was a must for me- no telling what may lurk in the old farm trees I get for firewood, particularly from fence-high level to stump.
After getting everything fixed, I cut out the goofy muffler 'catalytic' box and opened up the outlet to approx 3/4". When checking the H/L screws, they will only open 7/8 turn for the high and 3/4 for low. The shop manual and (I think) a few posts on this board recommend starting out at 1 full turn open. Putting aside the screw issue, Stihl recommends for the 066 12,000 rpm max with bar and chain. A Madsen's article I read recommends 13,000 rpm max w/o bar & chain.
But what about post muffler mod? Should I adjust for a higher max rpm? I would assume so- but what is my target rpm after the mod? I have a tach, so checking this won't be a problem. With the H screw all the way out (rich), I do get a little burbling at full throttle. I should have checked the pre-muffler mod rpms as post-mod it sounds much higher at full throttle.
Hopefully I can make the adjustments I need with the limited screw travel on the carb adjustments. I had not heard/read about stops on 066 screws- so I don't know what's up with that. Thanks in advance for your help, great site here.