-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Hello, I have been a bit under the weather lately. I returned to the saw this evening. I took the recoil off and I am able to turn the flywheel by hand, with the spark plug installed without any real difficulty. Therefore, I don't think it is a compression issue and that I am just too weak to pull the recoil. While I had the recoil off, I spray some lubricant in the areas that I thought would help. I put the recoil on and I could pull it several times normally. I then attempted to start the saw and it did the difficult pull thing; I couldn't start the saw. I took the plug out and it was wet but not overtly wet. I don't think the saw is hydro-locking at all. The more I played with the saw the more it felt like the recoil was kicking back on me. I took the recoil back off and decided to set the coil gap on the minimal setting of 0.15 mm. I tried it again and while it seemed different I couldn't start the saw. At that point I stopped as I wasn't feeling well and did not want to over exert myself. I could start throwing parts at it; a chinesium recoil is cheap.
I know the drop start is not usually recommended as it is dangerous for sure, but that's how i've always started my 029 super and every other saw. Brake is Off too. Truth be told this is how most people start their saws. It's just much easier.
I always start the saw on the ground as it is safer and it is not that I can't pull and start the saw. If I was to attempt to drop start it, it would do the same and I would probably end up getting hurt.
This saw has always started great, both cold or hot. Normally I put it on full choke, pull a few times and it burps, then on the second position of the choke, pull a few times and the saw is running, take the brake off and apply throttle. It has always been a good saw; it gets a bit heavy on me after a few hours of work. I wouldn't want a heavier saw. I know the photo of the flywheel with the nut off doesn't show it has shifted but I am wondering if it could have and it just doesn't look as if it has. I don't have a flywheel puller for this application. This is one of those things where you really need to be pulling the rope. I need to make that video of me starting the saw.
Clearly you know how to start the saw, that's Bang On as they say. Hopefully a starting video will show something to help figure out what's happening.
I haven't returned to the saw but hope to soon. I have been sick with a cold but I am on the mend.
Based on everything stated I am leaning towards a compression issue. I realize that is a really broad term so if it were mine here is what I would do:
1: pull plug and try it. You have done this and it turned over easy. Though not definite it is not likely bearings.
2. Clean the muffler and the exhaust port. Can't remember if you had done this. Can you easily blow through the muffler?
3. Check for proper spark. Part of the increase in compression can be due to it not firing at the right time and pushing the piston back down. I think you set the timing but check the ignition module as well.
4. Does starting with brake on or off make a difference?
5. Lastly I get a new jug and piston set. High compression can put stress on piston rods and other bearings. It can even cause piston rock at the top of the stroke which can cause rings to dig in. Might not be the answer but by the time I got to #5 I'm out of ideas.
You could try to put some carb cleaner in the cylinder and stroke it to the top. Put the plug in, turn it upside down and let it sit over night. Dump the cleaner and put a bit of oil in the cylinder and slowly turn it over to lube everything back up. Then try again.
1: pull plug and try it. You have done this and it turned over easy. Though not definite it is not likely bearings.
2. Clean the muffler and the exhaust port. Can't remember if you had done this. Can you easily blow through the muffler?
3. Check for proper spark. Part of the increase in compression can be due to it not firing at the right time and pushing the piston back down. I think you set the timing but check the ignition module as well.
4. Does starting with brake on or off make a difference?
5. Lastly I get a new jug and piston set. High compression can put stress on piston rods and other bearings. It can even cause piston rock at the top of the stroke which can cause rings to dig in. Might not be the answer but by the time I got to #5 I'm out of ideas.
You could try to put some carb cleaner in the cylinder and stroke it to the top. Put the plug in, turn it upside down and let it sit over night. Dump the cleaner and put a bit of oil in the cylinder and slowly turn it over to lube everything back up. Then try again.
You missed the recoil...
#5 is pretty extreem for diagnosing a hard starting issue
It is. Just trying to make a point that if I was that far in and it still wasn't right, I'd start tearing in deep. IIRC, an entire rebuild kit is around $100. Just to satisfy my curiosity as to why it is, I'd spend the money and time to do it. I still think there is something leading to the compression being to high.
That is a chineese rebuild kit,not OEM parts
It's a crap shoot as to what you get and how it will run.
This saw is a great running saw,in great shape from what the OP has put in the thread.
My money is on the recoil,as i have had a similar experience with a husky.
I assumed the squish was to tight and pulled it apart to add a gasket.The saw acted exactly the same after.Changed the recoil from another saw and it was fine.
I cut 8 cords of wood with it the previous year with no issues starting till i went to use it again.I had done a gasket delete without actually checking the squish,so i thought that was the issue.
Sean McGillicuddy
Minister of Fire
It might be what type of rope being used in the recoil ...
Yup, i never tried changing the rope in mine had another complete recoil to try.
I would think an issue with the recoil or rope would be present regardless of whether the plug was in or out. Then again I am awaiting the resolution. Internet troubleshooting can be tough.
Some recoil issues will be there all the time
But in this case when the plug is in and you require to pull through the compression, whatever is the issue is compounded with the compression.
So say if to small of rope is used,when there is no resistance it pulls easy, when you put a load on it the small rope gets pulled down in the pulley because it is to small and jambs between the rope on the pulley and the pulley causing major resistance.
Or if by chance the replacemnt recoil wasn't exactly the same and center is off a bit or the bearing surface of the pulley has some major issues and binds when pressure is put on it
Sean McGillicuddy
Minister of Fire
Or the replacement cord swells causing binding ...
@WoodGirl - My MS251 is doing the exact same thing you describe. I understand completely what you mean when it is hard to pull at times and other times only takes normal effort to pull. It is very clear there are two different kinds of effort - normal effort which is what is used when it will start and that jerky, mechanical, hard way like something is bound up. For me the hard to pull times feels the whole engine has bound up an I'm manually turning it over in some unnatural mechanical way.
Today it did again after having sat for most of the year. I pulled the spark plug since it felt like it was compression locked, plug was dry so it hadn't flooded from my starting attempts, replaced the plug and then it spun with normal starting effort. Started up after a few pulls and ran fine.
I have had it 7 years and don't use it much, maybe bucking up a couple trees max a year, so can't imagine I have any worn out parts.
Today it did again after having sat for most of the year. I pulled the spark plug since it felt like it was compression locked, plug was dry so it hadn't flooded from my starting attempts, replaced the plug and then it spun with normal starting effort. Started up after a few pulls and ran fine.
I have had it 7 years and don't use it much, maybe bucking up a couple trees max a year, so can't imagine I have any worn out parts.
My apologies for not updating. With my sickness; that that was almost two weeks for full recovery, to winter storms during this period to other delays, I haven't gotten back to the saw until today. The point where I last stopped was decreasing the flywheel coil gap to the lower value. Then with storms etc, I didn't have the chance to follow up. Today I started the saw and it would pull normal and then maybe one where you couldn't pull to then back normal. I got the saw started and it smoked and then cleared up; so probably oil left over after the fuel evaporated from trying to start before today. I let the saw run a minute and then cut it off. I got my PPE out and then started the saw again; again it would pull normal but for one or two pulls where it felt locked or kicking back. I started the saw and bucked some large dead poplar rounds until I let the chain hit the dirt. I stopped the saw and did some chain sharpening by hand. I then started the saw again where again it would pull normal then maybe once or twice the lockup or kickback (I am not really sure how to describe it). I finished bucking up the poplar logs and then stop the saw to do some splitting. I was able to start the saw three times within a few hours and the lockup kickback issue only occurred a few times.
Reducing the coil gap seems to have improve the saw starting but not eliminated it. Could this be a coil issue that the coil is not firing properly when it should? If so, are the aftermarket coils on fleabay any good?
Reducing the coil gap seems to have improve the saw starting but not eliminated it. Could this be a coil issue that the coil is not firing properly when it should? If so, are the aftermarket coils on fleabay any good?
I don't think it is a compression thing because it is comes and goes. Since this saw does not have reed valves, outside of carb puking too much fuel, what would cause the compression to go high and then back normal? When I had the recoil off, I could turn the flywheel through the compression without any real difficulty.
The Chinese parts are hit or miss. Very cheap, sometimes worthless.
Wait, I thought you had the plug out when you were turning it over with the recoil off? What causeS compression buildup (if that is the issue) is when you load the cylinder up with air and fuel and it doesn't fire.
So that goes back to the carb being the issue; excess fuel. I pull and have normal compression and then with the excessive fuel and air mixture, I get the "Issue" then when I pull again and it is normal pull that is because it exhausted the excess fuel and then it starts and runs OK. I have thought about getting a carb kit and clean and rebuild the carb with a new diaphram. Maybe it is "throwing parts at it" time to see if anything helps.
