Advice on fixing an MS310

[magna85]

Hi folks, long time lurker, this is my first post. Looking for advice on rebuilding a Stihl MS310.

Its my primary firewood saw. I bought it used about 10 years ago and it has served me well (doing side work for years and now the last 2 years in a new house heating primarily with wood). I took down 3 trees in January of this year without any trouble, and then it sat for a couple months. When i tried to use it in March it would start just fine and run on half choke. Taking the choke off would cause the saw to stall out unless you kept your finger on the throttle. Obviously something is up...changed air fiter and fuel filter and cleaned the carb. I checked the fuel pickup line and it did not appear cracked, i even put my mouth to it and blew into it and it held pressure fine. I had picked up a new fuel line but saw no reason to try and mess with that since the old one appeared OK. Put it back together and there was no improvement. So i dropped it off my local small engine shop at the beginning of the month. He took a look and told me the engine is toast. He stuck a camara in through the spark plug socket and told me the piston and cylinder walls are scored pretty bad.

This is a real bummer becuase the saw always ran great. When this all happened i JUST missed out on a used MS310 on craigslist. I can get by and do some light work with my MS170, but i need a bigger saw to finish up some trees I've already taken down this year.

I am looking to you fine folks for advice with attemping to rebuild the engine myself. I'm reasonably handy but I will admit I don't have any experience with 2 stroke engines. I see there are plenty of available piston kits as well as complete assembled piston and cylinder kits (that are more expensive but eliminate the precision work of getting the engine internals correct.

I know i could go out any buy a new saw, but my nature is to tinker and try and fix things. The advice from my small engine guy is the older Stihl saws are better built that the newer ones anyway. I'll probably borrow my fathers MS290 to get me buy and I'll keep a close eye on craigslist for anything that comes up for sale. That being said I plan to mess around with my current saw and try and get it going again.

I'd appreciate any advice on tearing apart the 310 and getting it running.

Thanks!

 

[Sean McGillicuddy]

Run some seefoam thru it.

 

[PaulOinMA]

The place where I bought my chainsaw and blower vacuum deals mostly with landscape professionals. They recommended I add Mechanic In A Bottle to gas for small engines. My chainsaw is just for occasional use.

They then recommended I use Trufuel since I don't run a lot of gas through my chainsaw and blower/vacuum.

 

[Sean McGillicuddy]

Oops
I should of read all of your post ..Sorry
That would be a lot of work ..keep an eye out for another ..

Ask on the Arborist site : https://www.arboristsite.com/community/

 

[johneh]

I think the first thing I would do is take the exhaust off
and look at the piston for scoring. This will tell you if your
small engine teck is correct. Overhauling that engine is not hard
and cheaper than a new saw

 

[salecker]

Your saw is a clamshell type saw,homeowner is another term.
If your piston is scored you will have to take the saw completely apart to fix it,unlike a professional model where you can just take the cylinder off.
If you did score the piston you may be able to save the original cylinder.Then all you would need is a new piston,seals maybe bearings.
Before you take it apart you should do a pressure and vacuum test to see why it scored.
Getting the IPL on the saw will help with disassembly and reassembly.
Resist the temptation to buy aftermarket parts.
There are a few decent aftermarket suppliers of parts,Metior for pistons,Caber for rings.
There is a sequence to disassemble the saw,one of the bar studs has to be removed to get it apart.
A fun and easy project to rebuild a saw.Enjoy bring it back to life

 

[Highbeam]

Loving my cheap makita 6400. Was a Home Depot rental saw. Only 250$ as I recall. Perfect “big” saw to complement your little one.

Just cut 5 cords with it yesterday in 4 hours and under 1 gallon of fuel.

 

[thewoodlands]

Hi folks, long time lurker, this is my first post. Looking for advice on rebuilding a Stihl MS310.

Its my primary firewood saw. I bought it used about 10 years ago and it has served me well (doing side work for years and now the last 2 years in a new house heating primarily with wood). I took down 3 trees in January of this year without any trouble, and then it sat for a couple months. When i tried to use it in March it would start just fine and run on half choke. Taking the choke off would cause the saw to stall out unless you kept your finger on the throttle. Obviously something is up...changed air fiter and fuel filter and cleaned the carb. I checked the fuel pickup line and it did not appear cracked, i even put my mouth to it and blew into it and it held pressure fine. I had picked up a new fuel line but saw no reason to try and mess with that since the old one appeared OK. Put it back together and there was no improvement. So i dropped it off my local small engine shop at the beginning of the month. He took a look and told me the engine is toast. He stuck a camara in through the spark plug socket and told me the piston and cylinder walls are scored pretty bad.

This is a real bummer becuase the saw always ran great. When this all happened i JUST missed out on a used MS310 on craigslist. I can get by and do some light work with my MS170, but i need a bigger saw to finish up some trees I've already taken down this year.

I am looking to you fine folks for advice with attemping to rebuild the engine myself. I'm reasonably handy but I will admit I don't have any experience with 2 stroke engines. I see there are plenty of available piston kits as well as complete assembled piston and cylinder kits (that are more expensive but eliminate the precision work of getting the engine internals correct.

I know i could go out any buy a new saw, but my nature is to tinker and try and fix things. The advice from my small engine guy is the older Stihl saws are better built that the newer ones anyway. I'll probably borrow my fathers MS290 to get me buy and I'll keep a close eye on craigslist for anything that comes up for sale. That being said I plan to mess around with my current saw and try and get it going again.

I'd appreciate any advice on tearing apart the 310 and getting it running.

Thanks!

I started having problems with my 310 over a year ago, it would run fine for 20 minutes and then just stop in the cut. I took it to the dealer I bought it from around three times but each time they told me it ran fine.

I took it to a second Stihl dealer and they gave me the same answer. Each time I brought it home I would start bucking up some wood and each time after 20 minutes it would stall out in the cut and then wouldn't start.

The first dealer called me about a parts saw he just took in with the same carb but newer than my 310 had. I went over and paid him 40 bucks for the saw with the understanding if it didn't work he would take it back and return the 40 bucks, the 310 with that newer carb has been running great since.

I will give the first dealer credit for not charging me after the first time I brought it back.

 

[ClintonH]

I started having problems with my 310 over a year ago, it would run fine for 20 minutes and then just stop in the cut. I took it to the dealer I bought it from around three times but each time they told me it ran fine.

I took it to a second Stihl dealer and they gave me the same answer. Each time I brought it home I would start bucking up some wood and each time after 20 minutes it would stall out in the cut and then wouldn't start.

The first dealer called me about a parts saw he just took in with the same carb but newer than my 310 had. I went over and paid him 40 bucks for the saw with the understanding if it didn't work he would take it back and return the 40 bucks, the 310 with that newer carb has been running great since.

I will give the first dealer credit for not charging me after the first time I brought it back.

Sounds similar to my experience. My dad has a 310 that has always bogged and cuts out like you describe. I bought my 310 7, 8 years ago from a pawnshop ($225). It's given me exactly 0 problems since then, doing anywhere from 5-10 cords per year. I wonder if there's a generational difference when the carb set up was changed.

 

[thewoodlands]

Sounds similar to my experience. My dad has a 310 that has always bogged and cuts out like you describe. I bought my 310 7, 8 years ago from a pawnshop ($225). It's given me exactly 0 problems since then, doing anywhere from 5-10 cords per year. I wonder if there's a generational difference when the carb set up was changed.

My 310 was great until just over a year ago, I usually cut 15 face cord a year. I did get mad enough when two of the Stihl dealers told me the same thing that I bought a new 311. I like the twist on filter on the 311, it does a much better job than the filter on the 310.

The first Stihl dealer did take my original carb out of the 310 and put in another one that he said was good, it did the same damn thing, 20 minutes cutting and the troulbes started.

I'm wondering if Stihl changed the carb manufacturer.

 

[SidecarFlip]

Waste of time using a borescope to look inside. Just take the muffler off and observe the piston and rings while cranking it over. Good time to remove any carbon from the muffler too.

I never use synthetic fuel. I use the Stihl pre mix. It has fuel stabilizer in it. None of my stuff likes the fake fuel anyway.

Mine are ocassional use too now that I'm retired. I run them dry when sitting, I mean DRY as in nothing in the fuel system and I drain the tanks beforehand as well and leave the fuel caps off and I cover them up with a large towel.