Husqvarna 128ld carb adjustments

[Doug01]

Hi,

Having some issues with the weed eater. It started to get hard to adjust then just wouldn’t run at full rpm. Primer wouldn’t prime. Did a quick clean of carb, new fuel filter and lines. Will idle OK but only way I could get the Rpms is with the high jet all the way in. May need to clean the carb better but where would you start on the carb settings. Mainly the idle screw? I had the high and low at about a turn and 1/8-1/2 out but had to just fiddle with all three to get it to idle. At first it would just die when I hit the gas and fuel would come out of the carb. I got it to where it sounded good...with jet all the way in but under full load it bogged after just a minute or two. Maybe I need a new carb. But I’d still like to know where to set the idle. Thanks

 

[Okie294life]

did you check the screen in the carb and make sure that you have all the gaskets in correctly, screws tight? Also lined up the vent hole in the intake gasket so that it can pump fuel? Did you take the jet screws out and blow them out? New carbs are pretty much non rebuildable. I used to kit stuff all the time until mfgs started going to the rotary valve style carbs. Next to impossible to clean or rebuild. If it’s the rotary valve style do yourself a favor and find a cheap OEM replacement on eBay and never look back.

 

[Chevboy0167]

Check the spark arrestor screen in the muffler to see if it is plugged with carbon. Also the exhaust port in the cylinder may be plug up with carbon also. May have to remove muffler to check the cylinder port. These must clean and clear.

When it bogs down, try loosening the fuel tank cap to allow air in. May have a plugged tank vent causing a fuel system vacuum.

It looks like your carb should be Zama W38. Standard butterfly carb.

http://www.zamacorp.com/tclist.html?cnum=C1Q-W38
Cheap on ebay.

https://www.ebay.com/itm/274500798538?epid=679420150&hash=item3fe985c84a:g:puYAAOSwaW1hc5mv

 

[Chevboy0167]

OEM rebuild kit is half price......LOL

https://www.ebay.com/itm/334112900588?epid=4048907787&hash=item4dcaae45ec:g:1IMAAOSwnY5gBuj9

 

[Doug01]

Thanks for the replies! I’ll admit the carb clean was just a quick spray out. There was definitely a bunch of crap in one of the screens. Need to get back in it some more.

I removed the screen on the exhaust...it wasn’t bad at all. Not sure on the ports. I’ll look in there.

I read in a chainsaw post to start with the hi and low about a turn or turn and 1/8 and to set the idle all the way open. Does that sound right?

 

[Doug01]

did you check the screen in the carb and make sure that you have all the gaskets in correctly, screws tight? Also lined up the vent hole in the intake gasket so that it can pump fuel? Did you take the jet screws out and blow them out? New carbs are pretty much non rebuildable. I used to kit stuff all the time until mfgs started going to the rotary valve style carbs. Next to impossible to clean or rebuild. If it’s the rotary valve style do yourself a favor and find a cheap OEM replacement on eBay and never look back.

I need to get deeper in the carb.

 

[Mad Professor]

Check the spark arrestor screen in the muffler to see if it is plugged with carbon. Also the exhaust port in the cylinder may be plug up with carbon also. May have to remove muffler to check the cylinder port. These must clean and clear.

When it bogs down, try loosening the fuel tank cap to allow air in. May have a plugged tank vent causing a fuel system vacuum.

It looks like your carb should be Zama W38. Standard butterfly carb.

http://www.zamacorp.com/tclist.html?cnum=C1Q-W38
Cheap on ebay.

https://www.ebay.com/itm/274500798538?epid=679420150&hash=item3fe985c84a:g:puYAAOSwaW1hc5mv

^^^^^^^^^^^^Mine plugs the spark screen up and will run like crap, won't rev^^^^^^^^^^^^^^

Otherwise besides spark plug and cleaning airfilter has been trouble free > 20 years.

 

[Chevboy0167]

Yeah.... mostly cuz string trimmers are not ran wide open enough to prevent the buildup. Also using a quality synthetic oil helps reduce it.