I was curious what the compression looked like on some of my old and new saws so I bought a cheap compression tester from Autozone. The tester does have a schrader valve in the tip and a release button so it is not a total piece of crap.
Here is a list of my OPE stuff that I tested. Some of these pieces of equipment have never had their plugs pulled out so it was a good oppurtunity to see if anything was running too rich or too lean also.
ProMac 10-10 1978 vintage, bought from Craigslist for $30.
145 lbs cold, plug was black but I haven't run this saw long enough to know why. I need to put a new plug in it and run it for a few tanks to know more, but I think I do need to lean the high side out some more.
Poulan 3400 1982 vintage, the one I restored.
120 lbs cold. Seemed a little low so I shot some 10-30 into the bore and tried again and it only went to 130 so maybe the rings are a little worn or the bore is a little worn, it just has lowish compression. Rings and bore both look very clean and the saw runs awesome, plug was a nice tan and gray. I don't think pulling this saw down and honing the bore and putting in new rings is worth 10lbs of compression.
Stihl BG 75 blower, about 10 years old.
120lbs cold, plug was a very clean gray with minimal ash. This has a fixed H jet. This machine starts and runs fine at this level of compression.
Echo CS-440 1 year old.
135 lbs cold, plug was a nice tan color but the top of the piston is black from carbon. I have been running 40-1 synthetic in everything for the past year but I am going to switch back to 50-1 synthetic and that should clean out by itself I think.
Echo SRM-2100 trimmer, bought this WELL used 12 years ago from a pawn shop for $45.00.
150 lbs cold, plug was tan and brown.
The only maintenance this machine has ever needed was a new purge bulb and grease in the gearbox. I love this trimmer.
Poulan Wild Thing, about 9 years old.
150 lbs cold, plug was tan and brown and is getting worn.
This is by far my most used saw as it was my only saw until I joined up here.
The bar and sprocket are totally shot on this saw and the chain adjuster parts are worn too. I always ran 50-1 in this saw and the piston is nearly spotless on top. I am going back to 50-1 synthetic. I have never touched the mixure settings on this saw either. I know it is a POS but wow! it is actually in great shape inside.
I guess there are a couple of lessons here for me. #1 Use 50-1 synthetic for cleaner guts.
#2 my machines with 120 lbs compression have just as good tuning manners and (percieved) power as the ones with 150. Certainly there are some saw models which we know should be XXXlbs compresison new and XXXlbs compression when worn out. I now know that sometimes a piece with 120lbs which would make some people around here scream "New rings!" is probably normal for that machine. Case in point, there is a guy on the bay that has a boner for Poulan 3400's and he usually has 3-4 for sale, he also always lists their compression and 130lbs was the highest I ever saw him post. This model of saw probably just came that way (120-130lbs) from the factory. My little blower also has 120lbs and probably came that way, it is well used but NOT abused. The lesson is, maybe you buy something used and the rings and piston look good but the compression is lower than XXX other saw you have- don't freak out! Run it first, maybe its normal!
Here is a list of my OPE stuff that I tested. Some of these pieces of equipment have never had their plugs pulled out so it was a good oppurtunity to see if anything was running too rich or too lean also.
ProMac 10-10 1978 vintage, bought from Craigslist for $30.
145 lbs cold, plug was black but I haven't run this saw long enough to know why. I need to put a new plug in it and run it for a few tanks to know more, but I think I do need to lean the high side out some more.
Poulan 3400 1982 vintage, the one I restored.
120 lbs cold. Seemed a little low so I shot some 10-30 into the bore and tried again and it only went to 130 so maybe the rings are a little worn or the bore is a little worn, it just has lowish compression. Rings and bore both look very clean and the saw runs awesome, plug was a nice tan and gray. I don't think pulling this saw down and honing the bore and putting in new rings is worth 10lbs of compression.
Stihl BG 75 blower, about 10 years old.
120lbs cold, plug was a very clean gray with minimal ash. This has a fixed H jet. This machine starts and runs fine at this level of compression.
Echo CS-440 1 year old.
135 lbs cold, plug was a nice tan color but the top of the piston is black from carbon. I have been running 40-1 synthetic in everything for the past year but I am going to switch back to 50-1 synthetic and that should clean out by itself I think.
Echo SRM-2100 trimmer, bought this WELL used 12 years ago from a pawn shop for $45.00.
150 lbs cold, plug was tan and brown.
The only maintenance this machine has ever needed was a new purge bulb and grease in the gearbox. I love this trimmer.
Poulan Wild Thing, about 9 years old.
150 lbs cold, plug was tan and brown and is getting worn.
This is by far my most used saw as it was my only saw until I joined up here.
The bar and sprocket are totally shot on this saw and the chain adjuster parts are worn too. I always ran 50-1 in this saw and the piston is nearly spotless on top. I am going back to 50-1 synthetic. I have never touched the mixure settings on this saw either. I know it is a POS but wow! it is actually in great shape inside.
I guess there are a couple of lessons here for me. #1 Use 50-1 synthetic for cleaner guts.
#2 my machines with 120 lbs compression have just as good tuning manners and (percieved) power as the ones with 150. Certainly there are some saw models which we know should be XXXlbs compresison new and XXXlbs compression when worn out. I now know that sometimes a piece with 120lbs which would make some people around here scream "New rings!" is probably normal for that machine. Case in point, there is a guy on the bay that has a boner for Poulan 3400's and he usually has 3-4 for sale, he also always lists their compression and 130lbs was the highest I ever saw him post. This model of saw probably just came that way (120-130lbs) from the factory. My little blower also has 120lbs and probably came that way, it is well used but NOT abused. The lesson is, maybe you buy something used and the rings and piston look good but the compression is lower than XXX other saw you have- don't freak out! Run it first, maybe its normal!
