Echo hedge trimmer

[38racing]

Friend of friend has asked me to look at it. He's already replaced gaskets and fuel grommet. Don't think he changed pump diaphragm. It starts and idles fine. Bogs but stays running ( I'll verify rpm later ) at higher throttle. Don't have model number with me as I post this. He also changed plug. It's the rotary style carb. I was thinking from previous research that the threaded piece with nut on the top is a mixture adjustment?

[bgsengine]

Friend of friend has asked me to look at it. He's already replaced gaskets and fuel grommet. Don't think he changed pump diaphragm. It starts and idles fine. Bogs but stays running ( I'll verify rpm later ) at higher throttle. Don't have model number with me as I post this. He also changed plug. It's the rotary style carb. I was thinking from previous research that the threaded piece with nut on the top is a mixture adjustment?

Sounds like classic symptoms of a plugged spark arrestor screen

Rotary valve carb is fully adjustable but need special tool for the idle speed. Also , if he had it apart , make sure and look down throttle bore and rotate throttle wide open and make sure the barrel hole lines up perfectly with the bore top and bottom , if it doesnt he probably lost the ramp roller - a very tiny 1 millimeter piece that will fall out when you remove the rotary valve (which almost never needs to be removed anyway even for cleaning) The o-ring and ramp roller are not part of any repair kit

[38racing]

thanks. I thought of the spark arrester after posting. forgot to mention that applying choke did not improve it.
possibly he did not have it fully apart as he gave me the new pump diaphragm and an old many holed gasket. said he had tried seafoam in it. got other projects to do first.

[38racing]

wasn't arrestor. found video which suggests lifting rotary to see if ramp roller is missing although things looked centred top to botomm on full throttle but I'm going to look again as I was looking more for side to side
. I misspoke about which diaphragm I have. I have the new metering diaphragm. the old gasket is the pump gasket . he didn't give me the old pump diaphragm. I was wondering if he mixed up the lines but both are in the fuel. primer bulb is full but pushing on it does not force fuel out of the return hose. puzzled a bit since carb kit seems to be about $18 usd but I thought that he said it cost him 125 cdn to get stuff from USA. my price for an aftermarket rb123 kit is $17 cdn.

[38racing]

also seeing a rb188 kit for rb-k75. which is number zama gives. wonder if it could be dirty input screen. had that on walbro.

[KE4AVB]

As BGS said all you got is the rotate the barrel to full throttle position and the hole should line up with the carburetor throat fully ie wide open.

Don't forget to set the metering lever too.

I just had a battle with RB-K93 on a SRM225. I ended up having to remove the main mixture adjusting screw to clean its thru hole and trash behind it. Of course the ball plug retainer had to be replaced when I got thru along the EPA plugs. Acted just a clogged spark arrester with no acceleration. Between the flooding from a slightly stiff metering diaphragm and the clogged it was showing its behind but I think I got it working now.

Zama has the rb-k75 kit as RB-188.

[38racing]

for almost the price of a kit I can get this for $22 cdn .
some stuff from this place arrives fast enough but wouldn't opt for the extra 14$ shipping.
https://m.banggood.com/Carburetor-Rebui ... 17721.html

[38racing]

as a first step I could just replace metering diaphragm and check for plugged screen and meter height.

[38racing]

wow. just found a hedge trimmer like his at homedepot.ca for $671 cdn. guess it's worth a bit of my time to check it out.

[38racing]

finally had a chance to look at this. I thought that the gasket between carb and spacer made no sense but it matches what I found on an IPL. I'm thinking that he had the intake and return lines reversed. Initially I thought about that but since he had return line immersed in fuel in tank I put it on back burner as it should still have picked up fuel. Now with lines off and I pressed the primer which was full of fuel , the fuel came out the nipple that had his filtered feed line on. Significant thing that I found was that IPL shows pump diaphragm against the carb housing , then gasket, then air purge body. He had the gasket against the the body. I'm thinking that pretty much would make it not run right.

update: found another pic on zama.com and obviously if he had lines reversed fuel can't be picked up from fuel return because of the check valve. If you are facing the air purge body with nipples facing down is the return nipple on your left? ok looking closer at pic it seems the fuel inlet has straight path through the air purge body to carb so I can check that tomorrow.