C1Q S186 KM55R

[PTmowerMech]

This thing is flooding like crazy. THE only way to keep it running is to shoot air in the venturee, constantly. Take the air away, and it floods. out.

Question: Is this solely a needle/Seat issue?

The gaskets and everything inside looks good. Metering leveler was spot on. It holds 7lbs
After cleaning it (not in the ultrasonic, which is broken) putting it all back together, pressure testing it and firing it up. It didn't flood like it was before. It'll start without pushing air thought it. But can't get it to idle for long. Not long enough change the low side. I removed the H so I could get it off what sounded like the strokin sound. Well, that worked except I was able to screw it in and it never got to the lean running sound.

Darn thing is giving me fits. I remember someone mentioning a H side that runs the same closed as open. But can't remember what they said about it.

 

[Fish]

Zamas had a problem with the welch plugs falling out.


Here is the 2019 retail price from the Stihl dealer around here:

4140 120 0619 Carburetor C1Q-S186 $34.50

 

[PTmowerMech]

Sorry about the above post, I was so aggravated, It didn't come out right.

I meant to say, I removed the limiter of the H. And put it back in. That's when I realized that it would stroke when out too far. And would get pretty close to being spot on at WOT. But screwing it in the rest of the way, nothing changed. I held the trigger, after the H bottomed out for about 30 seconds or more. So I'm sort of remembering what @bertsmobile1 (IIRC) said about this. That all the fuel, that was allowing it to run high RPM's, with the H closed, is coming through the low idle side. Which tells me that there's something internally wrong on the L side.
There's nothing in the L side hole, except the jet, right? So I can't understand how it would let the engine run at those RPM's just from the L side fuel.

 

[StarTech]

As Fish said some Zama have welch plugs that fall out leading to flooding issues. What the problem is Zama doesn't provide the correct size to replace them so you have to replace the whole carburetor. I usually see this on Stihl equipment only.

 

[PTmowerMech]

As Fish said some Zama have welch plugs that fall out leading to flooding issues. What the problem is Zama doesn't provide the correct size to replace them so you have to replace the whole carburetor. I usually see this on Stihl equipment only.

After cleaning it out and pressure testing, (and it holding at 7lbs) I think I fixed the flooding problem. Unless it's still flooding through the L side.

It seems Stens and the DC Spares don't have this carb. The kit, IIRC is an RB-100. Is that correct?

BTW, the welch plugs haven't fallen out.

 

[StarTech]

Please verify the carburetor model number. As if it is the C1Q-S186 the Carburetor kit is RB-161. Stihl PN 7010 871 0222

As for pressure test that only test the fuel pump, metering needle and seat. It soes not the check the metering side of the carburetor as that side can't be pressure/vac tested.

 

[Hammermechanicman]

Looks like that carb has a purge bulb.
Be sure the fuel inlet side holds 7psi.
Then press and release the purge bulb. Pressure should drop slightly an hold each time you press bulb.
Apply 7 psi pressure to purge line barb. Should hold pressure. If those are good look for bad check valve or welch plug fallen out.

 

[ILENGINE]

After cleaning it out and pressure testing, (and it holding at 7lbs) I think I fixed the flooding problem. Unless it's still flooding through the L side.

It seems Stens and the DC Spares don't have this carb. The kit, IIRC is an RB-100. Is that correct?

I wish Stens would stock that carb, It seems like that is the most popular part number for carb replacement on Stihl trimmers.

 

[StarTech]

The following seem reasonable enough.

http://www.boxstoreparts.com/Stihl-OEM-Carburetor-C1Q-S186-4140-120-0620.htm

 

[PTmowerMech]

The following seem reasonable enough.

http://www.boxstoreparts.com/Stihl-OEM-Carburetor-C1Q-S186-4140-120-0620.htm

WOW.. Thanks man. I didn't get this site when I googled this. This is a great price.