Stihl MS280 hard to pull

[tab_a]

I got this (non-running) saw for free, and know nothing of its history. When trying to start it, the pull is extremely 'jerky' and usually stops dead before the rope is all the way out. Removing the spark plug, I'm able to easily pull the rope all the way but I suspect its not as smooth as it should be.

Looking in the exhaust and the spark plug hole, what I can see of the piston and cylinder look good, without any of the damage I've seen in other threads I've researched.

I've torn it down maybe half way. There is just a hint of play at the flywheel, and absolutely none on the clutch side (maybe too tight?). Turning the flywheel by hand, I think it MAY be binding very slightly just after the piston gets to the exhaust port on the upstroke. Brake seems completely off, and doesn't appear to be binding.

Didn't have a long enough Torx to get to the bolts to remove the cylinder. While I wait for that to arrive, anything else I should check? Best guess where the problem will be?

Many thanks!

 

[pioneerguy600]

Is the flywheel rubbing on the coil, the magnets will be getting close to the coil as the piston passes the exhaust port.

 

[tab_a]

Is the flywheel rubbing on the coil, the magnets will be getting close to the coil as the piston passes the exhaust port.

No rubbing. Gap looks about right.
Thanks.

 

[Chainsaw Jim]

What kind of experience do you have with chainsaws? If you don't mind me asking.

 

[tab_a]

What kind of experience do you have with chainsaws? If you don't mind me asking.

Don't mind at all--not much. I do have a smaller Stihl, that runs. I've repaired or rebuilt a wide range of objects/machines--from vintage stereos to Jag engines. Just not chainsaws.

 

[Conquistador3]

Before a further teardown, try pulling the starter with the spark plug off. If it spins well, it may be a case of excessive compression.
Usual (albeit not only) cause is carbon buildup in the exhaust port. That's easily cleaned with a wood wedge or hard plastic scraper.
Always check the cheap and easy to fix things first.

 

[Okie]

If you are not experienced with the 280 (028) Stihls they will seem very jerky and hard to turn over as the rope comes out when they have real good compression 150 or more. They are easier at 125psi.

Did you ever try giving it a squirt of MIXED gas 50:1 in the carb throat and cranking? (to see if you got a pop)
When starting a Stihl 028 that has high compression gently pull the rope until you feel the stop as you say, then get a good grip and briskly pull thru the compression stroke. (But with the spark plug out and pulling the rope the engine should turn over smooth)
They will fool you if you have been using smaller saws that crank over easier.
And you annot check a Stihls compression using a automotive compression gauge, it will read low and not accurate.

 

[Chainsaw Jim]

I'm wondering if your flywheel is just stopping when the magnet catches the coil. Not making contact, but just a strong magnetic connection that hangs it up since you say it does it at tdc only.

 

[a. palmer jr.]

Another thing to check is excessive fluid in the crankcase, you can turn the saw upside down and drain it out the exhaust if there is. This isn't a common thing but I've seen it before.

 

[clintb]

There is just a hint of play at the flywheel

just like a car engine, just a hint of play in the crank.

 

[tab_a]

just like a car engine, just a hint of play in the crank.

If you are not experienced with the 280 (028) Stihls they will seem very jerky and hard to turn over as the rope comes out when they have real good compression 150 or more. They are easier at 125psi.

Did you ever try giving it a squirt of MIXED gas 50:1 in the carb throat and cranking? (to see if you got a pop)
When starting a Stihl 028 that has high compression gently pull the rope until you feel the stop as you say, then get a good grip and briskly pull thru the compression stroke. (But with the spark plug out and pulling the rope the engine should turn over smooth)
They will fool you if you have been using smaller saws that crank over easier.
And you annot check a Stihls compression using a automotive compression gauge, it will read low and not accurate.

Hmmmm.......the plot thickens: I pulled the spark plug out of the working 110AV and compared that pull to the MS280--both pulled easily. Maybe 10 minutes later put the plug back in the 280, pulled gently, then firmly, and it fired right up. Ran for a couple of seconds and quit. I was able to start it again several times but never could get it to idle. Pulling the trigger seemed to kill it.

Background--I bought the 110 and the guy gave me the 280, with it. All I knew about it was 'something' was broken (per the Stihl dealer) and it would be expensive to fix. WAG--would intake boot do this?

Suggestions on next steps?

I'm thinking I was trying to pull the starter rope too far? Short pull all that's needed?

Thanks again!

 

[a. palmer jr.]

You shouldn't have to pull the rope out all the way to the end, in fact you shouldn't. It sounds like the 280 just needs a little carburetor or fuel system work. Check the fuel line and filter and if they're okay you can then clean the carburetor and install a new kit in it. Also, a damaged or disconnected pulse hose will keep it from running. If it's disconnected from it's nipple it probably should be replaced because they get brittle. It's also possible the carburetor is adjusted too lean, the H and L screws can be adjusted to about 1 turn out from lightly seated and try again..

 

[lwn9186]

Take the recoil off and check the fan housing screws. They are known for backing out and wrecking havoc on the flywheel.

 

[Okie]

And if the rope is at the end of it's travel when you are crank testing someone has probably shortened the rope or you are not starting the crank cycle at the first TDC of the short rope cycle.. Not good on recoil assembly that the rope hits the end of the pull stroke constantly something including skin is going to eventually break loose.
Kinda sounds like fuel problem now.
And if you get it started and running good and you adjust the carb for what seems to be real good throttle response you can easily ruin the saw if the H jet is adjusted in CW just little too far, the engine will overheat and score the piston and cylinder in short period of time. A 1/4 turn on the H jet on some Stihls can be the difference between overheat and ok. Most say use a tach to adjust H jet so as too not overrev a saw but I've recently I've started using a tach, but main engine temp test is using a infrared thermometer to monitor the piston jug temp when the saw is in a full cut and it works great so as to test the actual operating temp of the saw. Overheat might be from other things, like clogged cooling fins, broken cooling fins on flywheel, etc. Stihl, homelite, Poulans, even the little bity saws operating temps on the jug are around 340 max and 400F is heads up indicator temp is getting too hot. If you see a piston jug reach 380 under a load rapidly it's headed for meltdown and a seizure usually.


Keep the H jet adjusted out CCW as far as possible and still get throttle response and good loading in the cut.
CW=lean=overheat
CCW= rich=maybe ok
I've seen old carb go lean on their own due to aging and a engine overheat.

 

[jonw440]

Sounds like the 034 I just got running. The drive side crank bearing decided to go talk to the piston top and spark plug.

 

[Okie]

Sounds like the 034 I just got running. The drive side crank bearing decided to go talk to the piston top and spark plug.

Ouch!!!!!!!!!!!!!!

 

[Definitive Dave]

If you are not experienced with the 280 (028) Stihls they will seem very jerky and hard to turn over as the rope comes out when they have real good compression 150 or more. They are easier at 125psi.

Did you ever try giving it a squirt of MIXED gas 50:1 in the carb throat and cranking? (to see if you got a pop)
When starting a Stihl 028 that has high compression gently pull the rope until you feel the stop as you say, then get a good grip and briskly pull thru the compression stroke. (But with the spark plug out and pulling the rope the engine should turn over smooth)
They will fool you if you have been using smaller saws that crank over easier.
And you annot check a Stihls compression using a automotive compression gauge, it will read low and not accurate.

028 and MS280 are completely different saws and the MS280 is a terrible saw in many ways, but if it pulls good without a plug and not with the plug, check that you have the right plug and it isn't too long and tapping your piston
be careful working on a 280 the coil and carb are both very pricey and OEM only the two of them as parts are worth more than the saw
the coils fail early, easily and often, my total wild butt guess is that the saw has a dead coil and the previous owner tried a spark plug as a fix and used whatever he had on hand and then gave up when the dealer told him the coil was bad

flywheel screws also a good idea but with a modern saw with the rough back Torx a little less likely and it would show the same behavior without the plug

Dave

 

[a. palmer jr.]

If it's the ignition module you can use one from an 026 or 024, very cheap on ebay..

 

[Definitive Dave]

If it's the ignition module you can use one from an 026 or 024, very cheap on ebay..

I think this is true for an 028 but I am pretty sure the MS280 uses a model specific coil that is oem only and $100+, if I am wrong please let me know that would be great.

 

[pioneerguy600]

I think this is true for an 028 but I am pretty sure the MS280 uses a model specific coil that is oem only and $100+, if I am wrong please let me know that would be great.

You are right Dave, that coil/module only fits the MS270 and MS 280.