air leak on small generator

[38racing]

holes in throttle plate? sounds like someone hacked together a carburetor and used a choke plate in place of throttle plate. highly likely you have a frankenstein carburetor, I'd suspect.

friend said he bought the carb new. this picture on Amazon shows holes too.
https://www.amazon.ca/POEMQ-Carburetor- ... 0706&psc=1

[KE4AVB]

Opening those holes would be the same screwing in the idle speed screw thus causing the to run at an increase minimum running speed.

[bgsengine]

Opening those holes would be the same screwing in the idle speed screw thus causing the to run at an increase minimum running speed.

Not necessarily.. got to remember some designs rely on air flow (venturi effect) between throttle plate and the idle jets to pull fuel out for proper mixture (and/or some carburetors do air & fuel mixing at the pilot jet/ idle mixing well) - so if air is bypassing that, same effect as an air leak.. a lot depends on the design of the carburetor - just because something fits doesn't mean it should work..

[KE4AVB]

Then maybe I have never seen one.

[bgsengine]

Possibly, me, I've never seen a THROTTLE plate with holes in it (other than the screw holes or alignment holes which go directly over throttle shaft anyways) on a single barrel small engine carburetor - wouldn't make sense to me to have a deliberate source of unmetered air like that... But as they are pictured in the carb linked by 38, they are indeed covered by the throttle shaft, but my only guess is , the plates were stamped as both throttle and choke (or for a 2-screw mount?) - just for the sake of faster production with fewer parts?? - but as long as those holes are not bleeding in unmetered air (that isn't being mixed with fuel) they should work.. but if I had that carb in with that problem and looking for air leaks, that'd be one thing I'd be taking a closer look at (whether the holes would allow extra air past the throttle plate that'd lean out the mixture)

[bgsengine]

BGS I was beginning to think you was in deep hibernation or maybe recoping from taking out a hand rail like I me doing. I just about did it again this morning. Porch cover in black ice again.

Pretty much - basically retired from the Small Engine business.. now just using the shop space as a woodworking shop... so I don't usually have a lot to contribute here these days, most questions seem to be getting answered pretty much as I'd expect.... weather here's been just as nasty, ice and snow and doesn't help that we've been dealing with a nasty head cold on top of all that.

[KE4AVB]

Thank goodness it is only a head cold...it could be the other thing.

With me avoiding people in general I have less problems of getting sick. Though my blood pressure wanted to show itself but I contributing that to some bad pills. It been fine since I got the new prescription refill. Different manufacture.

[38racing]

making progress. maybe. I had engine running OK but I couldn't set the rpm/hertz. it would be to fast so I'd back out the governor screw a tiny bit but then it would go past ideal to too slow. slight turn of screw but wouldn't stop at ideal but go back too high. I removed the tank and did static governor adjustment. doing so I noticed that the lever with the screw adjustment stop and governor spring end had a lot of play in the pivot. I replaced the pivot. unfortunately when I tested it was back to the wild surging. if I sprayed carb cleaner on throttle shaft it would smooth out for a bit. I also found that putting my finger there had same effect. since carb has idle mixture screw I backed it way out and sense some improvement. I tried with a 800 watt load. got surging same and again action at throttle shaft fixed it. then all a sudden surging stops. no load and with the load. so I again set about to set governor. I definitely see throttle open when load applied. what now puzzles me is that normally I set high speed no load hsnl to 61.2 so with load I get about 60. what I'm seeing now is a slightly lower rpm and hertz on hsnl than on load. I will setting it for 60 with the half load and continue testing. with my luck it will start surging again. I have a theory that there is still an air leak at hsnl but it's affect is diminished when throttle opens and that is why rpm actually increases as load opens the throttle

[38racing]

today's result. cold start it surged unless 1 notch of choke or carb spray. evened out as warmed up. apply load and major surge which cleared with spray and eventually evened out. same as before hsnl has lower rpm and hertz than 800 watts. it's rated 1000 continuous. so I sprayed at throttle shaft at no load and rpm goes up. if I spray with load there's no change. I'm going to pull carb and see if I can find something other than fuel line for a bushing. since bushing will project above carb body I can also seal it there.

[38racing]

getting nowhere really with this. I put some nail polish around outer edge of hose bushing where it enters carb. Performance about the same. I can get it to run at correct hz on load but as before off load it goes higher rather than lower. I removed the idle jet. It's got a real tiny hole. I used a small cleaner rod to open it slightly. No consistent change. On a lark a bought another cheap china carb from amazon. It has a few minor differences, just enough to be from different factory. Put it on and I was back to square one. Just surged like heck. So I'm back to the first carb. Still wonky. Can run on load but again it may surge when load applied. Something I found was that if it does surge and I hold the governor lever then it may even out and run fine. I'm beginning to wonder if there's an internal governor issue , coming and going or my bushing has some resistance on the throttle shaft.