problem MS200t

[waterworks]

i can't get a known good carb, but i'm thinking i might have to strip it again and re clean it, maybe ultra sonic it. The spark is still good after it dies, and the plug is maybe a little black & sooty, though i have not tuned this carb yet, and it's an old plug.

 

I will try a pop off test tommorow.

 

Thanks so far guys...

[waterworks]

Is there meant to be a check valve behind the H needle on this carb ?

[spudulike]

Is there meant to be a check valve behind the H needle on this carb ?

 

????? Check valve - get a picture and put an arrow as to what you mean.

 

If you are looking at the parts list, the check valve is the brass doofer in the venturi choke of the carb that expells the petrol vapour on full tilt.

 

It is refered to as a check valve rather than a jet as it has a one way valve in it - a jet doesn't!

[waterworks]

Yes the check valve in the main nozzle, i read about testing this by putting a tube in the high speed needle hole and sucking and blowing, so as to test the valve working, i tried this but i can suck air back through, it's very difficult to get a seal on any little bit of hose poked in there, so i'm not 100 % sure on this.

[spudulike]

Yes the check valve in the main nozzle, i read about testing this by putting a tube in the high speed needle hole and sucking and blowing, so as to test the valve working, i tried this but i can suck air back through, it's very difficult to get a seal on any little bit of hose poked in there, so i'm not 100 % sure on this.

 

You can do this, you need very soft rubber pipe - I usually put it on to the H screw fuel inlet under the diaphragm and seal the H screw hole.

 

You should find it easier to blow than suck if you know what I mean and don't swallow:blushing::lol:

[waterworks]

i never swallow.

[spudulike]

i never swallow.

 

Yes, burping inflammable petrol fumes is no fun, especially if you smoke:blushing:

[waterworks]

Ok iv'e been on the sick for a while but i'm back to this saw now,

 

i tried a pop off test , no pop at 30 psi, the max my mityvac will do, (the needle and seat were wet with wd40.) It falls slowly from 30 psi to 15 in about 60 seconds, then creeps down even slower.

[spudulike]

Ok iv'e been on the sick for a while but i'm back to this saw now,

 

i tried a pop off test , no pop at 30 psi, the max my mityvac will do, (the needle and seat were wet with wd40.) It falls slowly from 30 psi to 15 in about 60 seconds, then creeps down even slower.

 

Thats fine - I have noticed the old school big carbs pop off but the smaller modern ones don't at these pressures - what you have is OK!

[waterworks]

would a scored piston pass the crankcase pressure and vacuum test i did but still cause problems ?

 

what i saw of the piston via the ports did not look great.