Carb repair

[Freddie21]

I have questions regarding the cleaning of carbs. I disassemble them then soak in a water\Purple Power solution using a ultrasonic cleaner. Then I blow it out with air, spray with cleaner, use small wires in passages, clean with cleaner and finally shoot with air. This works with carbs that have removable jets. I have issues with the one with Welch plugs or none adjustable jets. I have not removed any plugs as I don't have replacements. In the case of the air\fuel mixture adjustment having holes under the Welch plug, if I remove it and clean the holes, does that new plug have to make an air tight seal? How about the plug inside the carb? I haven't seen a Welch plug assortment kit for small carbs, just for a certain car engine model. If anyone knows of one, please let me know.

Thanks all,

 

[StarTech]

I have questions regarding the cleaning of carbs. I disassemble them then soak in a water\Purple Power solution using a ultrasonic cleaner. Then I blow it out with air, spray with cleaner, use small wires in passages, clean with cleaner and finally shoot with air. This works with carbs that have removable jets. I have issues with the one with Welch plugs or none adjustable jets. I have not removed any plugs as I don't have replacements. In the case of the air\fuel mixture adjustment having holes under the Welch plug, if I remove it and clean the holes, does that new plug have to make an air tight seal? How about the plug inside the carb? I haven't seen a Welch plug assortment kit for small carbs, just for a certain car engine model. If anyone knows of one, please let me know.

Thanks all,

Yes it must be an air tight seal, that why replacement welch plugs are domed. In the case of the SV590 Nikki the welch in the repair kit. And most carburetors repair include the welch plugs. Even SV590 has over six pages of different spec numbers so for the correct you must have the spec number too.

And you won't find a welch plug assortment kit for small engines and even if there is one, 95+% chance that the plug you need wouldn't be in it.

Personally I have never removed a welch plug since I started using an USC. Now I do have a few to fall out that has to be replaced.

 

[Freddie21]

Even after cleaning with the USC, the carb surges. I was thinking it was due to not cleaning the jets under the plugs. Do you have this issue?

 

[bertsmobile1]

Surging when ?
at idle ?
when driving ?
with blades on ?
While the bulk of surging is from insufficient fuel, it can also be an air leak on the engine side of he main jet so a gasket or manifold leak .

 

[Freddie21]

Surges at any speed in Neutral and no load. New gasket on engine side, no air cleaner mounted (no effect when mounted) and sprayed around carb with cleaner to check for leaks. Has happened many of times with rebuilt (cleaned) or new Amazon carbs on different engines. Always set valve clearance first and verify good fuel and flow to carb. I have not adjusted governor.

 

[Tiger Small Engine]

Surges at any speed in Neutral and no load. New gasket on engine side, no air cleaner mounted (no effect when mounted) and sprayed around carb with cleaner to check for leaks. Has happened many of times with rebuilt (cleaned) or new Amazon carbs on different engines. Always set valve clearance first and verify good fuel and flow to carb. I have not adjusted governor.

Sometimes shortening the carburetor linkage spring, that attaches to the Governor helps improve hunting and surging. Make sure intake has no cracks or leaks, good gaskets (so no air leaks. Sometimes very slightly enlarging the pilot (idle) jet helps eliminate hunting and surging.

 

[StarTech]

Surges at any speed in Neutral and no load. New gasket on engine side, no air cleaner mounted (no effect when mounted) and sprayed around carb with cleaner to check for leaks. Has happened many of times with rebuilt (cleaned) or new Amazon carbs on different engines. Always set valve clearance first and verify good fuel and flow to carb. I have not adjusted governor.

As said governors can cause this but there are other possibles. Usually if it smooths out when you hold the throttle at the carburetor is it the governor but if not then it is in carburetor. This why you first determine where the problem exists and go from there. I lean burn and rich burn issues with carburetors. Usually rich burners either something you missed or someone in the past resized a jet. Also with the clones anything is possible.

I have had Kohler Courage singles to surge after determining that governor was the issue as it was play in the governor itself and I had to trick set the linkage to fix them. Other times it is the carburetor on an engine using governed idle where the bare minimum idle is not set correctly. Briggs V-twins usually have a governed idle setup.

So it is not as simple at times as this or that is the problem but a combination of problems. Only lots of experience will help fine your skills.

Sometimes shortening the carburetor linkage spring, that attaches to the Governor helps improve hunting and surging. Make sure intake has no cracks or leaks, good gaskets (so no air leaks. Sometimes very slightly enlarging the pilot (idle) jet helps eliminate hunting and surging.

And sometimes if someone had done this in the past it can actually cause the problem. Just depends on what the spring purpose is. On Honda engines there is a delicate balance even on the slack prevention springs. I once had a pressure washer with a Honda engine that surging like crazy where someone did this. New spring resolved the issue.

 

[Freddie21]

Appears only the carb was removed. The surging goes away if I either choke it 80% or hold the throttle arm preventing the governor from pulsing it. I will do a static adjustment this weekend. Thanks

 

[chuckpen]

did you remove and clean the main jet, idle jet and emulsion tube from carb?

I do not know about this carb but have been told there can be a "final screen" in some carbs on the fuel inlet, between the inlet and needle seat. Some carb clean in reverse as it were.

I'd also check your float is actually working and allows fuel to the correct height in the bowl. Could be sticky needle/seat or not "floating" high enough.

 

[Freddie21]

Don't think it's a carb problem as both carbs are identical and out of working machines. If I hold the throttle arm it runs great at any speed. Carbs have been completely cleaned. Thanks man