Tuning carbs with no L and H screws

[billpierce]

Get a teenie makita dcs230t which is ok, but occasionally get a bit chain creep, this is pretty random but usually only when been used for a while. Have turned the s screw (only one) down a bit but then it cuts out when dangling off a strop after a minute or two. Also noticed that it's exceeding it's max rpm (11.5k) sometimes up to 11.8 or 12k. Can't seem to alter this on the s screw? Any advice?

 

 

Also how to tune a bg55 blower?same one screw tuney thing.

 

Ta

 

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[billpierce]

 

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[Ferguson system]

You can adjust the carb by bending the plate that is pushing the float needle and membrane. It is located right under the membrane.

 

Bend it up/out towards the membrane will increase the fuel flow.

[billpierce]

Is that like the metering needle arm? How much to bend it?

 

With that spark plug colour does it need richening?

 

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[Richard Thompson]

I've never used one but I have seen a metering arm adjustment gauge from zama or walbro it might be useful ??

Just done a Google search and a few popped up if you need to see one.

Edited March 30, 2017 by Richard Thompson

[Little Al]

I've never used one but I have seen a metering arm adjustment gauge from zama or walbro it might be useful ??

Just done a Google search and a few popped up if you need to see one.

 

Both Walbro & Zama do a metering needle height gauge they are engraved for the carb model, & you just choose the carb model & lay the gauge across the carb where the metering arm is with the lettering lined up. The arm should just touch the gauge to correct the arm will require gentle bending up or down. The Walbro is a shaped letter W, the Zama is a letter "Z" IIRc At the time I bought mine they were around 4 Euro's each? Advertised on Flea bay

[billpierce]

Is that specifically for carbs with no L and H screws

 

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[Jiles]

All metering of gasoline, with a non adjustable carb, is accomplished with size of jets inside the carb.

I am in disagreement with adjusting the float level for more (richer) mixture.

What is puzzling about your particular situation is that your symptoms suggest an air leak. However, your spark plug suggest a rich mixture.

Spark plug color, of the porcelain surrounding the center electrode, should be light brown, like coffee with lots of cream, or light gray--NOT ANY SHADE OF WHITE.

[billpierce]

I wandered about an air leak too, but the saw really hasn't done much work from new just getting to the end of 2nd chain, so would be dissapointed if it is an airleak. On the bench I can adjust idle to something about right and get no chain creep, however it will stall after 10 seconds or so if clipped and hanging vertical on harness. Alternatively I can give it what sounds like slightly high idle which means it never cuts out when hanging but sometimes as it changes angle or after a cut the chain will run, not just a bit creep either enough to make me want to sort it out. Max rpm seems the same (slightly too high)though not too bothered about this if spark plug colour is looking good.

 

Thanks for the help

 

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[miker]

have you checked/cleaned clutch springs/shoes, just a thought