MS 260 suddenly hard to start

[bill147]

I have a year old MS260 and it has always started on the second or third pull. The last couple of weeks it's taken 30 to 50 pulls (and I'm too old to be pulling the started cord that many times) to get it running. The spark plug is gapped to spec, the air cleaner is clean, and the gas is fresh.

I've used the manual's recomendation for starting as well as different choke setting...all with no luck.

Prior to his saw, I had a Stilh 026 for 10 years or so and it always started within 3 or 4 pulls. Of course, it had the old carb on it.

Anybody have any good suggestions what my problem might be. It's been extremely humid here in Maryland the last couple of weeks...could that be a problem for the fixed jet carbs?

 

[Joey P]

There are a couple of things that I have seen that could be affecting this saw. First the spark plug could be going bad......we see it every now and then. I would recommend changing it with a WSR6-F Bosch spark plug.

Second it could be the choke lever is no longer closing the choke iin the air filter far enough.....this would make it extrememly hard to start. I have seen this a couple of times and all it takes is manipulating that choke lever to close the choke a little furthur.

Hope this helps!

 

[TonyM]

A fouled plug can spark outside of the combustion chamber, but then not spark during the compression stroke. It takes more voltage to jump a given gap when the pressure is higher, as during compression. If there is any question that your plug is bad, change it. From my experience with dirt bikes, two strokes start hard or won't start at all with a fouled plug.

 

[SilverBlue]

Hey Bill,
Make sure that there is a healthy spark, otherwise you may need a plug or perhaps the ignition module could be loose or going bad. Also make sure that the pulse tube is connected to the carb and crankcase.

 

[Crofter]

Sounds like it could be a fuel pick up or delivery problem. To decide if this is so, remove spark plug and drop in 5 (count them) drops of mixed gas, reinstall plug and attempt starting. If it fires right up this will tell you that the prob is fuel and not spark related. This also works well to get an engine going that has sat a while with a dried out carb.

Frank

 

[Kneejerk Bombas]

Why not just drip the gas down the carb?

If the exaust is clogged, it gets hard to start the saw too. Check the little screen.

 

[Crofter]

Mike; You are right about the exhaust screen. Gas dripped down the carb. would work too. Pulling the plug though, gives a chance to do a visual on its condition and clues perhaps to other problems.

Frank

 

[stihltech]

vapor lock

Now I was under the assumption that a Stihl with a working vent will not vapor lock. At least I do not experience any complaints to the fact from my customers. That is the whole idea to having the tank separate from the motor. The last Stihl I did have this problem on was the 041 super, but some extra air supply to the fan wheel cured that.
I am still sticking to a vent, fuel or pulse hose.
However, today brought an 026 into the shop with the same problem. Cure: remove foreign object from hi speed jet and tighten jet. Ran perfect after repair, and it even has a FIXED JET!

 

[Fish]

Even though the plug looks good, replace it with a new one,
as well as the fuel, as well as check the exhaust for blockage. While in there, look at the piston, and make sure the choke is
fully closing, do the simple checks first, it can save a lot of
aggravation.

 

[Kneejerk Bombas]

Re: duhhhhhhh

Originally posted by RockyJSquirrel
This problem is exaggerated in the fixed jet carbs since they are set so lean to begin with. Get with your Stihl tech to try and adjust for best performance and longest engine life.

How would a stihl tech be able to tell if the fixed jetting was too lean?

<B>With a tachometer!</B>

Originally posted by Fish
Even though the plug looks good, replace it with a new one,

NGK stock not doing so well, hey Fish?

In about 35 years of running two strokes, over twenty of those years doing it for a living, I have yet to have a spark plug replacement solve a two stroke engine problem. The most I have had to do is heat it up with a lighter or scrape some carbon off.
I'm sure one can go bad, it just very rarely does.
It makes more sense to remove the spark plug, inspect for indications of other problems, reinstall it into the plug wire, hold it against a ground, and pull the cord to see the spark.

This save you a buck and a half, and a trip to the hardware store.

 

[WRW]

bill147,
How is the throttle response after you get it started?

 

[stihltech]

plugs

Plugs not the problem? I cured 6 saws in the last 3 months with a new plug.
Is it always a defective plug, no. I see some suspect deposits now and then. I am not going to take a chance on a plug. this thing fires up to 14000 times a minute!
Had an 029 that would not perform. Changed the plug (looked like new) and ran great.
Plug fouled? Get rid of it.
Sure there are many other factors to chose from, and a defective plug is not high on the list. But if it is the problem, IT WILL DRIVE YOU CRAZY if you don't eliminate it from the list. Do the easy stuff first.

 

[stihltech]

tach

I seldom use a tach anymore. Take the saw out and put it in the wood. It should smooth out in the cut and have just a little blubber out. It still works, fixed jet or not.

 

[Joey P]

That is just it.........consumers who do not have the ear for proper carb adjustment or the skills to know what is happening as you adj the carb should not be adj the carb. I was watched for 2 years before I was able to (or comfortable with for that matter) adjusting the carb. I personally don't use a tach untill I am just done with the carb adjustment.....I use it to only make sure that my top end RPM is not exceeding what the factory tells me is safe.

As a dealer......if you buy the saw from me I adjust it for free. It takes me all of 10 minutes to do the adjustment and my customers really appreciate it.

Also......Champion plugs go bad all the time.....NGK is not tooo much better. We only use Bosch spark plugs. They RARELY fail us. I have solved more saw problems by changing out a champion plug.

 

[Fish]

I see more fouled out Bosch plugs than Champion, as I sell both.

I could clean and regap the old plug, but that is silly, I do it when
I am at home and don't want to go to town, but when you are
running a small engine shop, cleaning old plugs is silly.


Besides, I am getting filthy rich on screwing people selling them
a spark plug.

 

[dozerdan]

Try some of the Bosch plugs that are marked(made in India) you will appreciate all other makes of plugs
Later
Dan

 

[Kneejerk Bombas]

Originally posted by Joey P

As a dealer......if you buy the saw from me I adjust it for free. It takes me all of 10 minutes to do the adjustment and my customers really appreciate it.

So you can start the saw, warm it up, tach it, make a cut or two, go back into the shop and dismantle the carb, change out the jet to a different size, have all the different size and makes of jets in stock, re-assemble, and test run the saw, all in ten minutes?
Pretty good.

 

[bwalker]

When I set carbs I adjust the LS screw leaner till the saw will not idle then back it off to thr rich siude so it idles properly. I then set then set the HS with a tach to the factory spec. i next take the saw and make some cuts adjusting the screw all the while till I find the best rpm. I then write that rpm on the filter cover for future refferance. After this is done the saw can be set with a tach daily to ensure optimum performance. Try that with a fixed jet POS. With a fixed jet the saw runs crappy 9 times out of ten and with no way to correct it except taking the carb apart. Even then the steps in jet sizes are too great and you still cant get the thing to run like you can with a fixed jet.

 

[stihltech]

jets

I get then to run right every day. Onec I figured it out, I keep the correct jets.
I won't argue screws are not easier, I just experience too much "cure by adjustment". We all want it to be the carb, but it aint so. Those screws are nice and easy to get to.
I also do most of this tweaking under warranty. Once it is done, I have not seen it come back for a bad adjustment. Bad gas gumming things up, air leaks, dirty filters, bad hoses.
I do my job, maybe that is the difference.

 

[Joey P]

Re: jets

Originally posted by stihltech
I get then to run right every day. Onec I figured it out, I keep the correct jets.
I won't argue screws are not easier, I just experience too much "cure by adjustment". We all want it to be the carb, but it aint so. Those screws are nice and easy to get to.
I also do most of this tweaking under warranty. Once it is done, I have not seen it come back for a bad adjustment. Bad gas gumming things up, air leaks, dirty filters, bad hoses.
I do my job, maybe that is the difference.

AMEN......that is my philosophy also.......so many dealers want to make the sale and forget about it.