MS200 orange grommet in fuel tank??

[Gnarlyoak]

I ave noticed that there is an orange coloured grommet that sits in the roof of the fuel tank of an MS200, directly underneath where the breather valve sits on top of the tank.

 

What's it called? What's for? And how critical is it to the smooth operation of the saw?

 

Currently experiencing probs with my 200 and noticed that this grommet appears to have snapped off, leaving just the stub of the stud in the roof of the tank.

 

The saw starts up ok, thru choke & then half choke, but once the choke is off, the saw is really slow at picking up revs or running at idle. I have to constantly tickle the throttle, and make numerous restarts before the saw will run up properly. Once it warms up, it will run ok as normal for a while, but once it is hot, it will frequently stall out when idling and/or when I jerk it suddenly on the lanyard.

 

I've had it apart a couple of times now , and can't really seeing anything obvious apart from this orange grommet!! Any ideas anyone?

 

Many thanks in anticipation.

[Rich2484]

ok. first is it a 200t or just the 200?

 

the gromet is part of the breather and is a bit of a one way valve.

 

if the saw stops when its jerked then i would look at the carb boot for splits, if it does it when rotated from side to side (turned from up right to its side and then the other side then it may be crank seals leaking, but more info is needed? does it rev higher then normal or bog down? if it revs high then air leak in system, if it bogs and dies then an over rich mixture is to blame. clean air filter, clean carb and check meter arm hieght.

 

i would doubt very much if the valve mushroom shape part is the problem, i have seen many saws without that part work fine.

 

a good way to eliminate this is to slacken the fuel cap a bit and see if it runs or not, not very easy on a 200t as holding the saw flat without getting fuel leaking from cap.

 

also check to carb settings are on factory.

[Gnarlyoak]

Cheers Rich,

 

Sorry, yes it is a 200T.

 

The revs on the saw do not sound unusual, either to slow or fast, no chain creep! Once it is up and running, the saw appears to rev up & down quite normally when the throttle is depressed. Its just that initial start from cold when it seems it is at its most cantankerous, when it will take several restarts and lots of throttle wiggling to get it to stop stalling & build up the revs and then run relatively normally.

 

Stripped the saw down again today. Carb boot looks fine. Stripped carb, but no real sign of contamination. Gave the filter a good clean, it was a bit grubby but not exceptionally so. However did make a note to self to replace it at next available opportunity, as the filter is probably still the original on a 6yr old saw!

 

I have reset the carb settings to default, and retuned. I give it a run out tomorrow, and see how I get on.

 

Pardon my ignorance, but what is the "meter arm height"?

 

Thanks for you help mate.

[Rich2484]

There are some pics in the bench thread somewhere.

 

Will exclude some jargon on this.

 

When you took the carb apart you would have taken the side off with the four screws, under this is a black diaphragm, it has a metal disc on the middle. Now on the carb body is a small flat lever type part, this has a small spring under it, and is held by a bar and a screw to the side, near the screw will be the end of the lever, this has a drop pencil type valve on it going into the carb body.

 

This is the meter arm and valve, it works from pressure pushing down the the diaphragm thus pushing on the lever thus lift open the valve. And this allows fuel to flow.

 

The hight on a 200 carb should be level with the carb body, this is easily checked with a flat surface, I.e, a me tell ruler edge across the body, the arm should just touch the ruler edge, if it is too low the arm can be bent up gently with a flat screwdriver, or the reverse if too high.

 

Now this doesn't really sound like your problem. It does sound like it a bit rich and is taking it's time to warm up and burn the extra fuel. Could also be too much oil in fuel, or even the fuel itself, is it fresh.

[Gnarlyoak]

Well if its a fuel issue then I'm in no position to say weather or not its good or bad, stale or fresh. I'm a freelancer, so tend to use whatever fuel is supplied by whoever I'm working with/for.

 

Perhaps what may also be pertinent, is the fact that I had been putting up with problems with the saw whilst using it for 3 maybe 4 weeks with a broken breather valve. So it was running rough, too rich (air?), but problems now seem to have become worse since I finally replaced the valve a couple of weeks ago.

 

In the interim period, I have replaced the spark plug, its was a bit fubar'd! But hadn't before today attempted to retune the saw. Its sometimes a bit hit and miss when I try to retune a saw, I'm just as likely to make it worse as better... Now that I have, I'll put it through it paces on tomorrows job and see how I go on.

 

Thanks again, for your help bud.