OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Tecumseh / Kirby Engines carby adjustment

photos of carby

Thanks blackriverfish. I agree, it does not look as if that used to have a screwdriver slot. It still has an entry radius and I can't imagine the previous tenant having reproduced one of those, and polished the thing, if he/she had just finished ripping the screwdriver slot off it due to overenthusiasm.

You seem to now have a couple of options. The one I'd consider first, is trying to pull the whole main nozzle out of the carburetor. I'd try cleaning it up thoroughly to get the gum off, then use a short piece of steel tubing, with a longitudinal split down the outside, pushed over the outside of the bottom end of the main nozzle. Use a clamp around the outside of the tube to tighten it onto the main nozzle, then pull and/or twist the tube.

If you conclude that this will not work, you have a crude-fix option available. If you blast carburetor cleaner into the hole in the base of the main nozzle (using the long thin extension tube that comes with the can of cleaner), giving say three half-second bursts, you will probably clean out the whole length of the tube, and the main discharge orifice at the other end of it. What you probably won't do though, is open up the air ports near the bottom that make it an emulsifier - see red circle on diagram:



However it may be just about possible to clear them by putting your finger over the main discharge orifice (finger in the venturi of the carburetor) while you do the carb cleaner blasting, hoping that the plugs of gum in the radial holes will be pushed out and dissolved.

those 2 marks are reflected light,have given a good dose of carby cleaner and a lot gunk came out ,can u push it out from inside the venture .i looked the mixture screw under a magnification and it was very pitted.but the new one will fix that.

You may be able to push it out from the top, but that approach is fraught with difficulties. Here is a Honda (Keihin) one I tried that on:


The problem is that the top (main discharge) of emulsifiers is precisely shaped to do a job, and it will do a different one if its shape changes.

I think the key issue here is whether the main nozzle is actually held up by the float bowl retaining nut. If it is, it is now only supported by gum, and if you do a good enough job of removing the gum, it should drop out. Can you carefully inspect the top of the nut, and the bottom of the main nozzle, and tell us whether they are supposed to be in contact when the nut is screwed in fully? If they are, the nozzle is now only supported by gum, so you just need to remove nearly all the gum and soften the rest, then push the nozzle downward from the venturi end, as you proposed. I think it is safe to try this if you only push very gently on the top of the nozzle. If it won't drop out with gentle pressure, hit it again with the carb cleaner. I can tell you that we have had a couple of threads where people tried to do this with Honda carburetors and failed - presumably through not enough persistence with the carb cleaner, because on those carburetors the emulsion tube is definitely a loose fit in the carb body, and drops out readily if it is not gummed in.

On the other hand, if the top of the bowl nut does not contact and support the bottom of the main nozzle, it is probably a press fit and cannot be removed. If you look at the Carburetor Disassembly Procedure on Page 14 of the manual (Page 17 on the Acrobat page counter) it tells you to remove the "main nozzle tube" on Series 7 carburetors only. The subject is not mentioned for other series, and that makes me worry that it may not be removable.

well i have tried every thing and it wont move.i even pulled the butterfly s off and tried rotating it and it wont move and the bottom of the main nozzle doesn't touch so now i assume its a press fit.i put my finger over the outlet then filled it with cleaner 3or 4 times a lot of gunk came out so hopefully the air ways maybe just a little bit clean wont know till it assembled and tested.

If the bottom of the main nozzle doesn't touch the top of the bowl nut, it seems like the nozzle would have to be pressed in or it would not be positively located. That also lines up with the instructions only referring to it being removable on the Series 7 (yours is Series 3/4). So, the next trick is to get as much gum out as you can, then try it. Did any crud come out the last time you blasted it with the discharge nozzle blocked? When you do that, is crud coming out of the main air bleed, close to the throttle plate? If you can squirt cleaner in the bottom of the main nozzle and have it come out of the main air bleed, I think it has to be going through the radial holes to get there.

well i filled the tube with cleaner with my finger blocking it off then hit it with compressed air 6/7 times till it ran clear and that was after a soak.so not much i can do now but wait for parts to arrive then test added is a photo of tube in the venture

It would be worthwhile running the engine, and seeing how many turns of the main mixture adjustment screw gives the best results. If it is about 1.5 turns, chances are things are working reasonably well.

Remember to clean the small ports in the float bowl retaining nut - these seem to be Tecumseh's version of the main jet and idle jet:


Incidentally, there appear to be two screws holding the throttle plate to its shaft. That makes your carburetor a Series 4, not a Series 3 (which only has one screw, same as the choke).

yes it is a series 4 with 2 screws

well good news i reassembled carby with the old parts to test and it runs good no hunting bet not much adjustment but that will be fixed with the new parts,so i would like to thank you and this forum for all your help.will let you know how it goes with the new parts.

Thanks for keeping us up to date, blackriverfish. We hear very little about OHV Tecumsehs (as you may have gathered from all the uncertainty about whether the emulsifier was screwed or pressed in), so this thread will be useful to other people in the future.

It appears that the tube simply became fouled over time, and the previous owner did not know how to clean it so he bodged the mixture screw instead. Of course now you know how to clean and maintain it in a civilised way, like any other carburetor. I'll be interested in your comments on how pleasing an engine it is to use, once you finish the carburetor overhaul.

thanks yes i will keep you up to date as it is an old machine there will be more questions over time like how to deglaze friction plates.

well the parts arrived today so thanks spare parts department that was quick postage.

new carby kit installed and what a difference that makes,now running like a bought one.

So all may now be well until the carburetor gets gummed up again, which will take years, so you'll have forgotten how to fix it. However, that's why we have archives.

I'll close this thread.