Stihl love/hate MS251C

[ILENGINE]

The soft start saws are designed for whimps who can not overcome the engine compression
The secondary spring spins the engine at exactly the correct speed for starting .
Women or blokes with short ams who do not cause the engine to turn over on a single pull have no problems
Big boofy blokes who nearly rip the starting cord out of the engine every pull are the ones who have problems
Little pulls that may take 3 or 4 till it trips the secondary spring works best .
And as mentioned drop starting will not work.
I have a sneaky feeling that drop starting which is easy to mess up & cut yourself is probably the reason why it was designed
No saw company would make a design change that adds several extra parts unless they have been sued by a smart lawyer representing an idiot .

The soft start accomplished two things, Made it easier for the small people to start the saw and due to changes in timing to meet EPA standards prevents getting the rope ripped out of their hands when the saw kicks back which was very common on the 021-023-025 series saws around 2004. You could cold start the saw without any issues. Run the saw a few minutes and shut it off and then try to restart. About half the time it would pull the handle out of your hands and was told by a half a dozen Stihl dealers that was normal for the new saws without easy start.. Had several customers take their brand new saws back to the dealer and either had them retrofitted to the easy start or had the saws replaced with easy start saws.

 

[ILENGINE]

The 251c has a different primer system than other saws. The bulb is not a purge bulb. It pushes fuel into the fuel inlet of the carb. If you pump it too much you can pop off the metering needle and flood the engine. Only pump the bulb a couple times and then only pull the rope twice with the choke on. After that take it off choke and see if it starts.

On my MS251C it is a purge bulb and the fuel lines go from tank to carb inlet, carb outlet to primer inlet, and primer outlet back to tank. I can pump the bulb all I want and not flood the engine with gas.

 

[L10-11xx]

I know we have gotten off-topic but you are right in saying that what happened to change the starting of a chainsaw. This saw that I have been talking about is not for the guy or girl who is putting time out in the wood or looking for a load of firewood it is for the weekend doer. The question is would I or others out there buy this type of saw again I believe most would say hell no. Is this a good saw when running hell, yes it's a Stihl, but is it worth the BS in getting it started? For myself, I'll take my chances with the old saws and the lawyers.

 

[Hammermechanicman]

On my MS251C it is a purge bulb and the fuel lines go from tank to carb inlet, carb outlet to primer inlet, and primer outlet back to tank. I can pump the bulb all I want and not flood the engine with gas.

I have a 251c and it has the most ridiculous primer. It has a regular saw carb not designed for a purge bulb. The bulb pushes fuel into the carb fuel inlet and has a goofy bypass hose too. Only ever seen it on the 251c. The regular 251 doesn't have it.

 

[ILENGINE]

I have a 251c and it has the most ridiculous primer. It has a regular saw carb not designed for a purge bulb. The bulb pushes fuel into the carb fuel inlet and has a goofy bypass hose too. Only ever seen it on the 251c. The regular 251 doesn't have it.

Do you have one of those new 3 hose primer systems. If you have a non primer carb that has been fitted with a primer I wonder why even have the primer other than to make starting faster but more complicated.

 

[Hammermechanicman]

Yeah it is one of those. Looks like they just took a non purge carb and fabricobbled a primer bulb to it. I didn't buy it as it is a dumpster reacue. Great little saw. I am the guy with 5 saws and doesn't burn wood. Wife likes to razz me about too many saws so I switched to having too many Japanese cooking knives. She just rolls her eyes and shakes her head when the UPS truck shows up and she asks if it is mower parts or another knife.

 

[peanstein]

A clogged exhaust spark arrestor was the culprit for a saw I helped my in-law fix.
We took it off and torched it till all the build-up was gone. Problem solved.
This was after a thorough carb cleaning and a coil replacement, which did not remedy the issue.

 

[L10-11xx]

You are right a spark arrestor can give you fits, but that is not the case here it is a saw that has a mine of its own when it comes to starting. As I have said in the past I can get it started, but it is a crap shoot if I have the luck needed on any given day.

 

[slomo]

Next time you try to start it try this.
1. Push primer bulb 5 times, make sure it fills full.
2. Set at full choke.
3. Throttle wide open.
4. Pull rope until you hear it pop.
5. Move choke to half position.
6. Pull start.
This is the procedure I instruct my customers to use on both Stihl and Echo equipment.

Probably in the manual as well which doesn't get read.

 

[farmerdave1954]

You've probably already checked it, but I've seen a clogged air intake filter cause this same problem on Stihl FS series string trimmers and leaf blowers.