26cc 2T Carb No Adjustment

[Bailes1992]

My Father asked me to take a look at his McCulloch strimmer as it hadn't been used since last summer and wouldn't run.

I changed out the fuel/oil mix for fresh and it started right away and seemingly runs well with plenty of power. However, as soon as you hit full throttle and not a millimetre sooner, the engine bogs down and if left at full throttle for more than a second or two it will bog down to the point it cuts out.

I thought the high end fuelling was out but there is no adjustment screws on the carburettor at all? Is this normal? After this I went to look at the carb on my unbranded strimmer and also noticed there's no fuel adjustment screws. The only screw is for idle.

So anyone have any ideas what to do here? Like I said, other than at WOT, it runs perfectly. I'm not sure what to do next.

 

[Arch Stanton]

Clean the carb and make sure the air filter is clean also.

 

[Nukeman7]

My Father asked me to take a look at his McCulloch strimmer as it hadn't been used since last summer and wouldn't run.

I changed out the fuel/oil mix for fresh and it started right away and seemingly runs well with plenty of power. However, as soon as you hit full throttle and not a millimetre sooner, the engine bogs down and if left at full throttle for more than a second or two it will bog down to the point it cuts out.

I thought the high end fuelling was out but there is no adjustment screws on the carburettor at all? Is this normal? After this I went to look at the carb on my unbranded strimmer and also noticed there's no fuel adjustment screws. The only screw is for idle.

So anyone have any ideas what to do here? Like I said, other than at WOT, it runs perfectly. I'm not sure what to do next.

Most higher quality trimmers come with a Walbro or Zama carburetor, but many of the lower cost Chinese clones are showing up on lesser equipment. Can you post photos of the carburetors on both trimmers? Often, the carbs have adjustment screws hidden from view by emission controls mandated access restriction plugs and/or require special adjustment tools.

 

[Fordiesel69]

Remove both side of the carburetor and remove the needle. Shoot and scrub the straw of the carb cleaner on the fuel screen and agitate it agressivly. Make sure the fuel can flow THRU the screen in 1 or 2 seconds. Re-assemble and install a new metering diaphram. See if this helps, often it does.

 

[BrianF]

As already stated, get it clean before looking for adjustments.

 

[Cujet]

Some carbs have a very well hidden mixture screw in the center of the throttle barrel. It is under a cap.