ms200t problem

[andrew346]

i was having trouble with my ms200t, an intermittant problem that comes and goes, where it starts great but it sounds like its starving of fuel, you really have to keep blipping the throttle to keep it from dying and also the power is lacking when its like this.

Its not a simple matter of tuning, that doesnt cure it, so ive got the diaphragms and gaskets and also the inlet contol lever to rebuild the carb. While i was at it i got a new impulse hose as the old one was slightly kinked/crushed but not actually perforated or blocked. I also replaced the tank vent as the old one was missing part of the valve at the top.

I have my carb in bits here and one thing id like to do before i rebuild it is properly inspect and make sure the valve jet is not blocked, and to do this i would have assumed i need to press it out of the carb itself. The carb is a ZAMA S61D 441b and the workshop manual says to press it out with a drift in the direction of the venturi, i tried it kinda carefully just to see if it budged with out putting any hard pressure on it. I suppose im just a bit reluctant to put much force on it in case i wreck it. I tried to thread a thin brush bristle through it to clear it out but although it kept going further and further in, it wasnt coming out the other side, and then it wouldnt come back out. i went and snapped it, so theres part of a bristle in it now...

I noticed though that the inlet control lever was set really high, as if it was bent to compensate for maybe a poor diaphragm or something. hopefully this new metering diaphragm will help but im still left with the problem of removing the valve jet, anyone confirm how best to remove it? Does it just require quite a bit of force? Any help id be grateful
Regards
Andrew

 

[lcso10]

What about the spark arrestor? I worked on one not that long ago with similar problems. Wound up taking the muffler off and removing the spark arrestors. Run good after that. Hope this will help.

 

[epicklein22]

I agree, either the carb is worn out internally or the screen inside the muffler is blocked up. They run a ton better with the screen removed. Love those saws though.

 

[Paul001]

I'm sure this isn't what you wanna hear, but theres only one carb used on the 020/200T that is worth rebuilding. Yours isn't it.

I'd pop for the ~$65 for a new carb and get back to work. If the rest of the saw is in good mechanical condition, for what it can do, the saws worth spending the money on.

Paul

 

[pgg]

Pity your 200T's carb isn't a walbro, as you can slam the throttle and choke shafts into any other WT walbro carb you can find. (as long as your original shafts aren't worn) Any WT walbro carb will run sweet on a 200T. Can't swap zama shafts to walbros coz the zama shafts are .25mm thicker than the walbro ones. Best to just throw in another carb.

Stay clear of the accelerator pump carbs too. P.S. if your zama has the accel-pump, it's likely that's the problem. The brass piston and rubber O-ring wear and air leaks straight to the fuel nozzle. The accel-pump piston and O-ring are available as new parts.

Another way is to block the accel-pump circuit completely. On the air-filter side of the carb there's a small oval welch plug, flick it off and plug/epoxy the hole beneath. If lucky, the saw'll run sweet again..

 

[andrew346]

thanks for the replies.. i really do think it is a carb problem and even though the s61 carb may not be the best, i already have the new diaphragms and gaskets bought so i may as well rebuild the carb and see if it helps.

I know it isnt a blocked spark arrester as its a uk saw and it didnt come with one! i was confused at the grooves/tracks inside the mufler initially but then i remembered that the US saws had to have spark screens.

This still leaves me with the problem of the valve jet. i wanted to remove it for cleaning but now as ive tried to clean it with a fine brush bristle which got stuck inside and then snapped as i tried to withdraw it.. it looks like ill need a new jet. Anyone here ever removed the jet out of this particular carb? how does it come out?

Also i noticed that the hole isnt actually in the centre of the jet, its hard to describe unless you already know what im getting at. If the hole itself isnt in the centre of the circle, does it makes a difference as to what way you reinstall it in the carb as the jet installs diagonally into the carb?

Lastly where is the lo speed jet in this carb?, i see something that looks like a smaller jet under the inlet control lever but the manual doesnt seem to mention it.

thanks in advance for anymore replies
a

 

[SkipD]

Sounds to me like you may have a leaky fuel hose. If the fuel line has cracks in it, the fuel pump in the carburetor will suck air into the fuel line along with the fuel at times. When it does, performance goes to he!! in a hand basket really quick. Mine got so bad I couldn't restart the bugger.

Once I got a really good look at the fuel line (where it kinks 180° under the carburetor), the problem was obvious. After installing a replacement fuel line, the little bugger went back to chewing up wood really nicely.

 

[andrew346]

yeah id hoped for something like that! a cheap and easy fix but alas not so! i took the fuel hose off and inspected it carefully, hoping for it to be damaged but nope. even blew into it while blocking the other end to check for invisible holes but i had to rule it out im afraid. but thanks anyway for the suggestion
a

 

[SkipD]

yeah id hoped for something like that! a cheap and easy fix but alas not so! i took the fuel hose off and inspected it carefully, hoping for it to be damaged but nope. even blew into it while blocking the other end to check for invisible holes but i had to rule it out im afraid. but thanks anyway for the suggestion
a

Did you really carefully look (with high magnification) at the metal (brass?) tube that connects the rubber fuel line to the carburetor? If the bond between the metal tube and the aluminum has gotten buggered up, as an example, you'd have the very same symptoms.